kernel: update kernel 3.10 to 3.10.24
[openwrt.git] / target / linux / generic / patches-3.10 / 100-overlayfs.patch
1 --- a/Documentation/filesystems/Locking
2 +++ b/Documentation/filesystems/Locking
3 @@ -66,6 +66,7 @@ prototypes:
4         int (*atomic_open)(struct inode *, struct dentry *,
5                                 struct file *, unsigned open_flag,
6                                 umode_t create_mode, int *opened);
7 +       int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
8  
9  locking rules:
10         all may block
11 @@ -93,6 +94,7 @@ removexattr:  yes
12  fiemap:                no
13  update_time:   no
14  atomic_open:   yes
15 +dentry_open:   no
16  
17         Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
18  victim.
19 --- /dev/null
20 +++ b/Documentation/filesystems/overlayfs.txt
21 @@ -0,0 +1,199 @@
22 +Written by: Neil Brown <neilb@suse.de>
23 +
24 +Overlay Filesystem
25 +==================
26 +
27 +This document describes a prototype for a new approach to providing
28 +overlay-filesystem functionality in Linux (sometimes referred to as
29 +union-filesystems).  An overlay-filesystem tries to present a
30 +filesystem which is the result over overlaying one filesystem on top
31 +of the other.
32 +
33 +The result will inevitably fail to look exactly like a normal
34 +filesystem for various technical reasons.  The expectation is that
35 +many use cases will be able to ignore these differences.
36 +
37 +This approach is 'hybrid' because the objects that appear in the
38 +filesystem do not all appear to belong to that filesystem.  In many
39 +cases an object accessed in the union will be indistinguishable
40 +from accessing the corresponding object from the original filesystem.
41 +This is most obvious from the 'st_dev' field returned by stat(2).
42 +
43 +While directories will report an st_dev from the overlay-filesystem,
44 +all non-directory objects will report an st_dev from the lower or
45 +upper filesystem that is providing the object.  Similarly st_ino will
46 +only be unique when combined with st_dev, and both of these can change
47 +over the lifetime of a non-directory object.  Many applications and
48 +tools ignore these values and will not be affected.
49 +
50 +Upper and Lower
51 +---------------
52 +
53 +An overlay filesystem combines two filesystems - an 'upper' filesystem
54 +and a 'lower' filesystem.  When a name exists in both filesystems, the
55 +object in the 'upper' filesystem is visible while the object in the
56 +'lower' filesystem is either hidden or, in the case of directories,
57 +merged with the 'upper' object.
58 +
59 +It would be more correct to refer to an upper and lower 'directory
60 +tree' rather than 'filesystem' as it is quite possible for both
61 +directory trees to be in the same filesystem and there is no
62 +requirement that the root of a filesystem be given for either upper or
63 +lower.
64 +
65 +The lower filesystem can be any filesystem supported by Linux and does
66 +not need to be writable.  The lower filesystem can even be another
67 +overlayfs.  The upper filesystem will normally be writable and if it
68 +is it must support the creation of trusted.* extended attributes, and
69 +must provide valid d_type in readdir responses, at least for symbolic
70 +links - so NFS is not suitable.
71 +
72 +A read-only overlay of two read-only filesystems may use any
73 +filesystem type.
74 +
75 +Directories
76 +-----------
77 +
78 +Overlaying mainly involves directories.  If a given name appears in both
79 +upper and lower filesystems and refers to a non-directory in either,
80 +then the lower object is hidden - the name refers only to the upper
81 +object.
82 +
83 +Where both upper and lower objects are directories, a merged directory
84 +is formed.
85 +
86 +At mount time, the two directories given as mount options are combined
87 +into a merged directory:
88 +
89 +  mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper /overlay
90 +
91 +Then whenever a lookup is requested in such a merged directory, the
92 +lookup is performed in each actual directory and the combined result
93 +is cached in the dentry belonging to the overlay filesystem.  If both
94 +actual lookups find directories, both are stored and a merged
95 +directory is created, otherwise only one is stored: the upper if it
96 +exists, else the lower.
97 +
98 +Only the lists of names from directories are merged.  Other content
99 +such as metadata and extended attributes are reported for the upper
100 +directory only.  These attributes of the lower directory are hidden.
101 +
102 +whiteouts and opaque directories
103 +--------------------------------
104 +
105 +In order to support rm and rmdir without changing the lower
106 +filesystem, an overlay filesystem needs to record in the upper filesystem
107 +that files have been removed.  This is done using whiteouts and opaque
108 +directories (non-directories are always opaque).
109 +
110 +The overlay filesystem uses extended attributes with a
111 +"trusted.overlay."  prefix to record these details.
112 +
113 +A whiteout is created as a symbolic link with target
114 +"(overlay-whiteout)" and with xattr "trusted.overlay.whiteout" set to "y".
115 +When a whiteout is found in the upper level of a merged directory, any
116 +matching name in the lower level is ignored, and the whiteout itself
117 +is also hidden.
118 +
119 +A directory is made opaque by setting the xattr "trusted.overlay.opaque"
120 +to "y".  Where the upper filesystem contains an opaque directory, any
121 +directory in the lower filesystem with the same name is ignored.
122 +
123 +readdir
124 +-------
125 +
126 +When a 'readdir' request is made on a merged directory, the upper and
127 +lower directories are each read and the name lists merged in the
128 +obvious way (upper is read first, then lower - entries that already
129 +exist are not re-added).  This merged name list is cached in the
130 +'struct file' and so remains as long as the file is kept open.  If the
131 +directory is opened and read by two processes at the same time, they
132 +will each have separate caches.  A seekdir to the start of the
133 +directory (offset 0) followed by a readdir will cause the cache to be
134 +discarded and rebuilt.
135 +
136 +This means that changes to the merged directory do not appear while a
137 +directory is being read.  This is unlikely to be noticed by many
138 +programs.
139 +
140 +seek offsets are assigned sequentially when the directories are read.
141 +Thus if
142 +  - read part of a directory
143 +  - remember an offset, and close the directory
144 +  - re-open the directory some time later
145 +  - seek to the remembered offset
146 +
147 +there may be little correlation between the old and new locations in
148 +the list of filenames, particularly if anything has changed in the
149 +directory.
150 +
151 +Readdir on directories that are not merged is simply handled by the
152 +underlying directory (upper or lower).
153 +
154 +
155 +Non-directories
156 +---------------
157 +
158 +Objects that are not directories (files, symlinks, device-special
159 +files etc.) are presented either from the upper or lower filesystem as
160 +appropriate.  When a file in the lower filesystem is accessed in a way
161 +the requires write-access, such as opening for write access, changing
162 +some metadata etc., the file is first copied from the lower filesystem
163 +to the upper filesystem (copy_up).  Note that creating a hard-link
164 +also requires copy_up, though of course creation of a symlink does
165 +not.
166 +
167 +The copy_up may turn out to be unnecessary, for example if the file is
168 +opened for read-write but the data is not modified.
169 +
170 +The copy_up process first makes sure that the containing directory
171 +exists in the upper filesystem - creating it and any parents as
172 +necessary.  It then creates the object with the same metadata (owner,
173 +mode, mtime, symlink-target etc.) and then if the object is a file, the
174 +data is copied from the lower to the upper filesystem.  Finally any
175 +extended attributes are copied up.
176 +
177 +Once the copy_up is complete, the overlay filesystem simply
178 +provides direct access to the newly created file in the upper
179 +filesystem - future operations on the file are barely noticed by the
180 +overlay filesystem (though an operation on the name of the file such as
181 +rename or unlink will of course be noticed and handled).
182 +
183 +
184 +Non-standard behavior
185 +---------------------
186 +
187 +The copy_up operation essentially creates a new, identical file and
188 +moves it over to the old name.  The new file may be on a different
189 +filesystem, so both st_dev and st_ino of the file may change.
190 +
191 +Any open files referring to this inode will access the old data and
192 +metadata.  Similarly any file locks obtained before copy_up will not
193 +apply to the copied up file.
194 +
195 +On a file opened with O_RDONLY fchmod(2), fchown(2), futimesat(2) and
196 +fsetxattr(2) will fail with EROFS.
197 +
198 +If a file with multiple hard links is copied up, then this will
199 +"break" the link.  Changes will not be propagated to other names
200 +referring to the same inode.
201 +
202 +Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory
203 +object in overlayfs will not contain valid absolute paths, only
204 +relative paths leading up to the filesystem's root.  This will be
205 +fixed in the future.
206 +
207 +Some operations are not atomic, for example a crash during copy_up or
208 +rename will leave the filesystem in an inconsistent state.  This will
209 +be addressed in the future.
210 +
211 +Changes to underlying filesystems
212 +---------------------------------
213 +
214 +Offline changes, when the overlay is not mounted, are allowed to either
215 +the upper or the lower trees.
216 +
217 +Changes to the underlying filesystems while part of a mounted overlay
218 +filesystem are not allowed.  If the underlying filesystem is changed,
219 +the behavior of the overlay is undefined, though it will not result in
220 +a crash or deadlock.
221 --- a/Documentation/filesystems/vfs.txt
222 +++ b/Documentation/filesystems/vfs.txt
223 @@ -362,6 +362,7 @@ struct inode_operations {
224         int (*atomic_open)(struct inode *, struct dentry *,
225                                 struct file *, unsigned open_flag,
226                                 umode_t create_mode, int *opened);
227 +       int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
228  };
229  
230  Again, all methods are called without any locks being held, unless
231 @@ -681,6 +682,12 @@ struct address_space_operations {
232         but instead uses bmap to find out where the blocks in the file
233         are and uses those addresses directly.
234  
235 +  dentry_open: this is an alternative to f_op->open(), the difference is that
236 +       this method may open a file not necessarily originating from the same
237 +       filesystem as the one i_op->open() was called on.  It may be
238 +       useful for stacking filesystems which want to allow native I/O directly
239 +       on underlying files.
240 +
241  
242    invalidatepage: If a page has PagePrivate set, then invalidatepage
243          will be called when part or all of the page is to be removed
244 --- a/MAINTAINERS
245 +++ b/MAINTAINERS
246 @@ -6019,6 +6019,13 @@ F:       drivers/scsi/osd/
247  F:     include/scsi/osd_*
248  F:     fs/exofs/
249  
250 +OVERLAYFS FILESYSTEM
251 +M:     Miklos Szeredi <miklos@szeredi.hu>
252 +L:     linux-fsdevel@vger.kernel.org
253 +S:     Supported
254 +F:     fs/overlayfs/*
255 +F:     Documentation/filesystems/overlayfs.txt
256 +
257  P54 WIRELESS DRIVER
258  M:     Christian Lamparter <chunkeey@googlemail.com>
259  L:     linux-wireless@vger.kernel.org
260 --- a/fs/Kconfig
261 +++ b/fs/Kconfig
262 @@ -67,6 +67,7 @@ source "fs/quota/Kconfig"
263  
264  source "fs/autofs4/Kconfig"
265  source "fs/fuse/Kconfig"
266 +source "fs/overlayfs/Kconfig"
267  
268  config GENERIC_ACL
269         bool
270 --- a/fs/Makefile
271 +++ b/fs/Makefile
272 @@ -105,6 +105,7 @@ obj-$(CONFIG_QNX6FS_FS)             += qnx6/
273  obj-$(CONFIG_AUTOFS4_FS)       += autofs4/
274  obj-$(CONFIG_ADFS_FS)          += adfs/
275  obj-$(CONFIG_FUSE_FS)          += fuse/
276 +obj-$(CONFIG_OVERLAYFS_FS)     += overlayfs/
277  obj-$(CONFIG_UDF_FS)           += udf/
278  obj-$(CONFIG_SUN_OPENPROMFS)   += openpromfs/
279  obj-$(CONFIG_OMFS_FS)          += omfs/
280 --- a/fs/ecryptfs/main.c
281 +++ b/fs/ecryptfs/main.c
282 @@ -567,6 +567,13 @@ static struct dentry *ecryptfs_mount(str
283         s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
284         s->s_blocksize = path.dentry->d_sb->s_blocksize;
285         s->s_magic = ECRYPTFS_SUPER_MAGIC;
286 +       s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
287 +
288 +       rc = -EINVAL;
289 +       if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
290 +               pr_err("eCryptfs: maximum fs stacking depth exceeded\n");
291 +               goto out_free;
292 +       }
293  
294         inode = ecryptfs_get_inode(path.dentry->d_inode, s);
295         rc = PTR_ERR(inode);
296 --- a/fs/internal.h
297 +++ b/fs/internal.h
298 @@ -42,11 +42,6 @@ static inline int __sync_blockdev(struct
299  extern void __init chrdev_init(void);
300  
301  /*
302 - * namei.c
303 - */
304 -extern int __inode_permission(struct inode *, int);
305 -
306 -/*
307   * namespace.c
308   */
309  extern int copy_mount_options(const void __user *, unsigned long *);
310 @@ -132,12 +127,6 @@ extern struct dentry *__d_alloc(struct s
311  extern ssize_t __kernel_write(struct file *, const char *, size_t, loff_t *);
312  
313  /*
314 - * splice.c
315 - */
316 -extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
317 -               loff_t *opos, size_t len, unsigned int flags);
318 -
319 -/*
320   * pipe.c
321   */
322  extern const struct file_operations pipefifo_fops;
323 --- a/fs/namei.c
324 +++ b/fs/namei.c
325 @@ -402,6 +402,7 @@ int __inode_permission(struct inode *ino
326  
327         return security_inode_permission(inode, mask);
328  }
329 +EXPORT_SYMBOL(__inode_permission);
330  
331  /**
332   * sb_permission - Check superblock-level permissions
333 @@ -2868,9 +2869,12 @@ finish_open_created:
334         error = may_open(&nd->path, acc_mode, open_flag);
335         if (error)
336                 goto out;
337 -       file->f_path.mnt = nd->path.mnt;
338 -       error = finish_open(file, nd->path.dentry, NULL, opened);
339 -       if (error) {
340 +
341 +       BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
342 +       error = vfs_open(&nd->path, file, current_cred());
343 +       if (!error) {
344 +               *opened |= FILE_OPENED;
345 +       } else {
346                 if (error == -EOPENSTALE)
347                         goto stale_open;
348                 goto out;
349 --- a/fs/namespace.c
350 +++ b/fs/namespace.c
351 @@ -1442,6 +1442,33 @@ void drop_collected_mounts(struct vfsmou
352         namespace_unlock();
353  }
354  
355 +/**
356 + * clone_private_mount - create a private clone of a path
357 + *
358 + * This creates a new vfsmount, which will be the clone of @path.  The new will
359 + * not be attached anywhere in the namespace and will be private (i.e. changes
360 + * to the originating mount won't be propagated into this).
361 + *
362 + * Release with mntput().
363 + */
364 +struct vfsmount *clone_private_mount(struct path *path)
365 +{
366 +       struct mount *old_mnt = real_mount(path->mnt);
367 +       struct mount *new_mnt;
368 +
369 +       if (IS_MNT_UNBINDABLE(old_mnt))
370 +               return ERR_PTR(-EINVAL);
371 +
372 +       down_read(&namespace_sem);
373 +       new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
374 +       up_read(&namespace_sem);
375 +       if (IS_ERR(new_mnt))
376 +               return ERR_CAST(new_mnt);
377 +
378 +       return &new_mnt->mnt;
379 +}
380 +EXPORT_SYMBOL_GPL(clone_private_mount);
381 +
382  int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
383                    struct vfsmount *root)
384  {
385 --- a/fs/open.c
386 +++ b/fs/open.c
387 @@ -800,8 +800,7 @@ struct file *dentry_open(const struct pa
388         f = get_empty_filp();
389         if (!IS_ERR(f)) {
390                 f->f_flags = flags;
391 -               f->f_path = *path;
392 -               error = do_dentry_open(f, NULL, cred);
393 +               error = vfs_open(path, f, cred);
394                 if (!error) {
395                         /* from now on we need fput() to dispose of f */
396                         error = open_check_o_direct(f);
397 @@ -818,6 +817,26 @@ struct file *dentry_open(const struct pa
398  }
399  EXPORT_SYMBOL(dentry_open);
400  
401 +/**
402 + * vfs_open - open the file at the given path
403 + * @path: path to open
404 + * @filp: newly allocated file with f_flag initialized
405 + * @cred: credentials to use
406 + */
407 +int vfs_open(const struct path *path, struct file *filp,
408 +            const struct cred *cred)
409 +{
410 +       struct inode *inode = path->dentry->d_inode;
411 +
412 +       if (inode->i_op->dentry_open)
413 +               return inode->i_op->dentry_open(path->dentry, filp, cred);
414 +       else {
415 +               filp->f_path = *path;
416 +               return do_dentry_open(filp, NULL, cred);
417 +       }
418 +}
419 +EXPORT_SYMBOL(vfs_open);
420 +
421  static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
422  {
423         int lookup_flags = 0;
424 --- /dev/null
425 +++ b/fs/overlayfs/Kconfig
426 @@ -0,0 +1,10 @@
427 +config OVERLAYFS_FS
428 +       tristate "Overlay filesystem support"
429 +       help
430 +         An overlay filesystem combines two filesystems - an 'upper' filesystem
431 +         and a 'lower' filesystem.  When a name exists in both filesystems, the
432 +         object in the 'upper' filesystem is visible while the object in the
433 +         'lower' filesystem is either hidden or, in the case of directories,
434 +         merged with the 'upper' object.
435 +
436 +         For more information see Documentation/filesystems/overlayfs.txt
437 --- /dev/null
438 +++ b/fs/overlayfs/Makefile
439 @@ -0,0 +1,7 @@
440 +#
441 +# Makefile for the overlay filesystem.
442 +#
443 +
444 +obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
445 +
446 +overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
447 --- /dev/null
448 +++ b/fs/overlayfs/copy_up.c
449 @@ -0,0 +1,387 @@
450 +/*
451 + *
452 + * Copyright (C) 2011 Novell Inc.
453 + *
454 + * This program is free software; you can redistribute it and/or modify it
455 + * under the terms of the GNU General Public License version 2 as published by
456 + * the Free Software Foundation.
457 + */
458 +
459 +#include <linux/fs.h>
460 +#include <linux/slab.h>
461 +#include <linux/file.h>
462 +#include <linux/splice.h>
463 +#include <linux/xattr.h>
464 +#include <linux/security.h>
465 +#include <linux/uaccess.h>
466 +#include <linux/sched.h>
467 +#include "overlayfs.h"
468 +
469 +#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
470 +
471 +static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new)
472 +{
473 +       ssize_t list_size, size;
474 +       char *buf, *name, *value;
475 +       int error;
476 +
477 +       if (!old->d_inode->i_op->getxattr ||
478 +           !new->d_inode->i_op->getxattr)
479 +               return 0;
480 +
481 +       list_size = vfs_listxattr(old, NULL, 0);
482 +       if (list_size <= 0) {
483 +               if (list_size == -EOPNOTSUPP)
484 +                       return 0;
485 +               return list_size;
486 +       }
487 +
488 +       buf = kzalloc(list_size, GFP_KERNEL);
489 +       if (!buf)
490 +               return -ENOMEM;
491 +
492 +       error = -ENOMEM;
493 +       value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
494 +       if (!value)
495 +               goto out;
496 +
497 +       list_size = vfs_listxattr(old, buf, list_size);
498 +       if (list_size <= 0) {
499 +               error = list_size;
500 +               goto out_free_value;
501 +       }
502 +
503 +       for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
504 +               size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
505 +               if (size <= 0) {
506 +                       error = size;
507 +                       goto out_free_value;
508 +               }
509 +               error = vfs_setxattr(new, name, value, size, 0);
510 +               if (error)
511 +                       goto out_free_value;
512 +       }
513 +
514 +out_free_value:
515 +       kfree(value);
516 +out:
517 +       kfree(buf);
518 +       return error;
519 +}
520 +
521 +static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
522 +{
523 +       struct file *old_file;
524 +       struct file *new_file;
525 +       loff_t old_pos = 0;
526 +       loff_t new_pos = 0;
527 +       int error = 0;
528 +
529 +       if (len == 0)
530 +               return 0;
531 +
532 +       old_file = ovl_path_open(old, O_RDONLY);
533 +       if (IS_ERR(old_file))
534 +               return PTR_ERR(old_file);
535 +
536 +       new_file = ovl_path_open(new, O_WRONLY);
537 +       if (IS_ERR(new_file)) {
538 +               error = PTR_ERR(new_file);
539 +               goto out_fput;
540 +       }
541 +
542 +       /* FIXME: copy up sparse files efficiently */
543 +       while (len) {
544 +               size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
545 +               long bytes;
546 +
547 +               if (len < this_len)
548 +                       this_len = len;
549 +
550 +               if (signal_pending_state(TASK_KILLABLE, current)) {
551 +                       error = -EINTR;
552 +                       break;
553 +               }
554 +
555 +               bytes = do_splice_direct(old_file, &old_pos,
556 +                                        new_file, &new_pos,
557 +                                        this_len, SPLICE_F_MOVE);
558 +               if (bytes <= 0) {
559 +                       error = bytes;
560 +                       break;
561 +               }
562 +
563 +               len -= bytes;
564 +       }
565 +
566 +       fput(new_file);
567 +out_fput:
568 +       fput(old_file);
569 +       return error;
570 +}
571 +
572 +static char *ovl_read_symlink(struct dentry *realdentry)
573 +{
574 +       int res;
575 +       char *buf;
576 +       struct inode *inode = realdentry->d_inode;
577 +       mm_segment_t old_fs;
578 +
579 +       res = -EINVAL;
580 +       if (!inode->i_op->readlink)
581 +               goto err;
582 +
583 +       res = -ENOMEM;
584 +       buf = (char *) __get_free_page(GFP_KERNEL);
585 +       if (!buf)
586 +               goto err;
587 +
588 +       old_fs = get_fs();
589 +       set_fs(get_ds());
590 +       /* The cast to a user pointer is valid due to the set_fs() */
591 +       res = inode->i_op->readlink(realdentry,
592 +                                   (char __user *)buf, PAGE_SIZE - 1);
593 +       set_fs(old_fs);
594 +       if (res < 0) {
595 +               free_page((unsigned long) buf);
596 +               goto err;
597 +       }
598 +       buf[res] = '\0';
599 +
600 +       return buf;
601 +
602 +err:
603 +       return ERR_PTR(res);
604 +}
605 +
606 +static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
607 +{
608 +       struct iattr attr = {
609 +               .ia_valid =
610 +                    ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
611 +               .ia_atime = stat->atime,
612 +               .ia_mtime = stat->mtime,
613 +       };
614 +
615 +       return notify_change(upperdentry, &attr);
616 +}
617 +
618 +static int ovl_set_mode(struct dentry *upperdentry, umode_t mode)
619 +{
620 +       struct iattr attr = {
621 +               .ia_valid = ATTR_MODE,
622 +               .ia_mode = mode,
623 +       };
624 +
625 +       return notify_change(upperdentry, &attr);
626 +}
627 +
628 +static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry,
629 +                             struct path *lowerpath, struct kstat *stat,
630 +                             const char *link)
631 +{
632 +       int err;
633 +       struct path newpath;
634 +       umode_t mode = stat->mode;
635 +
636 +       /* Can't properly set mode on creation because of the umask */
637 +       stat->mode &= S_IFMT;
638 +
639 +       ovl_path_upper(dentry, &newpath);
640 +       WARN_ON(newpath.dentry);
641 +       newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link);
642 +       if (IS_ERR(newpath.dentry))
643 +               return PTR_ERR(newpath.dentry);
644 +
645 +       if (S_ISREG(stat->mode)) {
646 +               err = ovl_copy_up_data(lowerpath, &newpath, stat->size);
647 +               if (err)
648 +                       goto err_remove;
649 +       }
650 +
651 +       err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry);
652 +       if (err)
653 +               goto err_remove;
654 +
655 +       mutex_lock(&newpath.dentry->d_inode->i_mutex);
656 +       if (!S_ISLNK(stat->mode))
657 +               err = ovl_set_mode(newpath.dentry, mode);
658 +       if (!err)
659 +               err = ovl_set_timestamps(newpath.dentry, stat);
660 +       mutex_unlock(&newpath.dentry->d_inode->i_mutex);
661 +       if (err)
662 +               goto err_remove;
663 +
664 +       ovl_dentry_update(dentry, newpath.dentry);
665 +
666 +       /*
667 +        * Easiest way to get rid of the lower dentry reference is to
668 +        * drop this dentry.  This is neither needed nor possible for
669 +        * directories.
670 +        */
671 +       if (!S_ISDIR(stat->mode))
672 +               d_drop(dentry);
673 +
674 +       return 0;
675 +
676 +err_remove:
677 +       if (S_ISDIR(stat->mode))
678 +               vfs_rmdir(upperdir->d_inode, newpath.dentry);
679 +       else
680 +               vfs_unlink(upperdir->d_inode, newpath.dentry);
681 +
682 +       dput(newpath.dentry);
683 +
684 +       return err;
685 +}
686 +
687 +/*
688 + * Copy up a single dentry
689 + *
690 + * Directory renames only allowed on "pure upper" (already created on
691 + * upper filesystem, never copied up).  Directories which are on lower or
692 + * are merged may not be renamed.  For these -EXDEV is returned and
693 + * userspace has to deal with it.  This means, when copying up a
694 + * directory we can rely on it and ancestors being stable.
695 + *
696 + * Non-directory renames start with copy up of source if necessary.  The
697 + * actual rename will only proceed once the copy up was successful.  Copy
698 + * up uses upper parent i_mutex for exclusion.  Since rename can change
699 + * d_parent it is possible that the copy up will lock the old parent.  At
700 + * that point the file will have already been copied up anyway.
701 + */
702 +static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
703 +                          struct path *lowerpath, struct kstat *stat)
704 +{
705 +       int err;
706 +       struct kstat pstat;
707 +       struct path parentpath;
708 +       struct dentry *upperdir;
709 +       const struct cred *old_cred;
710 +       struct cred *override_cred;
711 +       char *link = NULL;
712 +
713 +       ovl_path_upper(parent, &parentpath);
714 +       upperdir = parentpath.dentry;
715 +
716 +       err = vfs_getattr(&parentpath, &pstat);
717 +       if (err)
718 +               return err;
719 +
720 +       if (S_ISLNK(stat->mode)) {
721 +               link = ovl_read_symlink(lowerpath->dentry);
722 +               if (IS_ERR(link))
723 +                       return PTR_ERR(link);
724 +       }
725 +
726 +       err = -ENOMEM;
727 +       override_cred = prepare_creds();
728 +       if (!override_cred)
729 +               goto out_free_link;
730 +
731 +       override_cred->fsuid = stat->uid;
732 +       override_cred->fsgid = stat->gid;
733 +       /*
734 +        * CAP_SYS_ADMIN for copying up extended attributes
735 +        * CAP_DAC_OVERRIDE for create
736 +        * CAP_FOWNER for chmod, timestamp update
737 +        * CAP_FSETID for chmod
738 +        * CAP_MKNOD for mknod
739 +        */
740 +       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
741 +       cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
742 +       cap_raise(override_cred->cap_effective, CAP_FOWNER);
743 +       cap_raise(override_cred->cap_effective, CAP_FSETID);
744 +       cap_raise(override_cred->cap_effective, CAP_MKNOD);
745 +       old_cred = override_creds(override_cred);
746 +
747 +       mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
748 +       if (ovl_path_type(dentry) != OVL_PATH_LOWER) {
749 +               err = 0;
750 +       } else {
751 +               err = ovl_copy_up_locked(upperdir, dentry, lowerpath,
752 +                                        stat, link);
753 +               if (!err) {
754 +                       /* Restore timestamps on parent (best effort) */
755 +                       ovl_set_timestamps(upperdir, &pstat);
756 +               }
757 +       }
758 +
759 +       mutex_unlock(&upperdir->d_inode->i_mutex);
760 +
761 +       revert_creds(old_cred);
762 +       put_cred(override_cred);
763 +
764 +out_free_link:
765 +       if (link)
766 +               free_page((unsigned long) link);
767 +
768 +       return err;
769 +}
770 +
771 +int ovl_copy_up(struct dentry *dentry)
772 +{
773 +       int err;
774 +
775 +       err = 0;
776 +       while (!err) {
777 +               struct dentry *next;
778 +               struct dentry *parent;
779 +               struct path lowerpath;
780 +               struct kstat stat;
781 +               enum ovl_path_type type = ovl_path_type(dentry);
782 +
783 +               if (type != OVL_PATH_LOWER)
784 +                       break;
785 +
786 +               next = dget(dentry);
787 +               /* find the topmost dentry not yet copied up */
788 +               for (;;) {
789 +                       parent = dget_parent(next);
790 +
791 +                       type = ovl_path_type(parent);
792 +                       if (type != OVL_PATH_LOWER)
793 +                               break;
794 +
795 +                       dput(next);
796 +                       next = parent;
797 +               }
798 +
799 +               ovl_path_lower(next, &lowerpath);
800 +               err = vfs_getattr(&lowerpath, &stat);
801 +               if (!err)
802 +                       err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
803 +
804 +               dput(parent);
805 +               dput(next);
806 +       }
807 +
808 +       return err;
809 +}
810 +
811 +/* Optimize by not copying up the file first and truncating later */
812 +int ovl_copy_up_truncate(struct dentry *dentry, loff_t size)
813 +{
814 +       int err;
815 +       struct kstat stat;
816 +       struct path lowerpath;
817 +       struct dentry *parent = dget_parent(dentry);
818 +
819 +       err = ovl_copy_up(parent);
820 +       if (err)
821 +               goto out_dput_parent;
822 +
823 +       ovl_path_lower(dentry, &lowerpath);
824 +       err = vfs_getattr(&lowerpath, &stat);
825 +       if (err)
826 +               goto out_dput_parent;
827 +
828 +       if (size < stat.size)
829 +               stat.size = size;
830 +
831 +       err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
832 +
833 +out_dput_parent:
834 +       dput(parent);
835 +       return err;
836 +}
837 --- /dev/null
838 +++ b/fs/overlayfs/dir.c
839 @@ -0,0 +1,605 @@
840 +/*
841 + *
842 + * Copyright (C) 2011 Novell Inc.
843 + *
844 + * This program is free software; you can redistribute it and/or modify it
845 + * under the terms of the GNU General Public License version 2 as published by
846 + * the Free Software Foundation.
847 + */
848 +
849 +#include <linux/fs.h>
850 +#include <linux/namei.h>
851 +#include <linux/xattr.h>
852 +#include <linux/security.h>
853 +#include <linux/cred.h>
854 +#include "overlayfs.h"
855 +
856 +static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
857 +
858 +static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
859 +{
860 +       int err;
861 +       struct dentry *newdentry;
862 +       const struct cred *old_cred;
863 +       struct cred *override_cred;
864 +
865 +       /* FIXME: recheck lower dentry to see if whiteout is really needed */
866 +
867 +       err = -ENOMEM;
868 +       override_cred = prepare_creds();
869 +       if (!override_cred)
870 +               goto out;
871 +
872 +       /*
873 +        * CAP_SYS_ADMIN for setxattr
874 +        * CAP_DAC_OVERRIDE for symlink creation
875 +        * CAP_FOWNER for unlink in sticky directory
876 +        */
877 +       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
878 +       cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
879 +       cap_raise(override_cred->cap_effective, CAP_FOWNER);
880 +       override_cred->fsuid = GLOBAL_ROOT_UID;
881 +       override_cred->fsgid = GLOBAL_ROOT_GID;
882 +       old_cred = override_creds(override_cred);
883 +
884 +       newdentry = lookup_one_len(dentry->d_name.name, upperdir,
885 +                                  dentry->d_name.len);
886 +       err = PTR_ERR(newdentry);
887 +       if (IS_ERR(newdentry))
888 +               goto out_put_cred;
889 +
890 +       /* Just been removed within the same locked region */
891 +       WARN_ON(newdentry->d_inode);
892 +
893 +       err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
894 +       if (err)
895 +               goto out_dput;
896 +
897 +       ovl_dentry_version_inc(dentry->d_parent);
898 +
899 +       err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
900 +       if (err)
901 +               vfs_unlink(upperdir->d_inode, newdentry);
902 +
903 +out_dput:
904 +       dput(newdentry);
905 +out_put_cred:
906 +       revert_creds(old_cred);
907 +       put_cred(override_cred);
908 +out:
909 +       if (err) {
910 +               /*
911 +                * There's no way to recover from failure to whiteout.
912 +                * What should we do?  Log a big fat error and... ?
913 +                */
914 +               pr_err("overlayfs: ERROR - failed to whiteout '%s'\n",
915 +                      dentry->d_name.name);
916 +       }
917 +
918 +       return err;
919 +}
920 +
921 +static struct dentry *ovl_lookup_create(struct dentry *upperdir,
922 +                                       struct dentry *template)
923 +{
924 +       int err;
925 +       struct dentry *newdentry;
926 +       struct qstr *name = &template->d_name;
927 +
928 +       newdentry = lookup_one_len(name->name, upperdir, name->len);
929 +       if (IS_ERR(newdentry))
930 +               return newdentry;
931 +
932 +       if (newdentry->d_inode) {
933 +               const struct cred *old_cred;
934 +               struct cred *override_cred;
935 +
936 +               /* No need to check whiteout if lower parent is non-existent */
937 +               err = -EEXIST;
938 +               if (!ovl_dentry_lower(template->d_parent))
939 +                       goto out_dput;
940 +
941 +               if (!S_ISLNK(newdentry->d_inode->i_mode))
942 +                       goto out_dput;
943 +
944 +               err = -ENOMEM;
945 +               override_cred = prepare_creds();
946 +               if (!override_cred)
947 +                       goto out_dput;
948 +
949 +               /*
950 +                * CAP_SYS_ADMIN for getxattr
951 +                * CAP_FOWNER for unlink in sticky directory
952 +                */
953 +               cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
954 +               cap_raise(override_cred->cap_effective, CAP_FOWNER);
955 +               old_cred = override_creds(override_cred);
956 +
957 +               err = -EEXIST;
958 +               if (ovl_is_whiteout(newdentry))
959 +                       err = vfs_unlink(upperdir->d_inode, newdentry);
960 +
961 +               revert_creds(old_cred);
962 +               put_cred(override_cred);
963 +               if (err)
964 +                       goto out_dput;
965 +
966 +               dput(newdentry);
967 +               newdentry = lookup_one_len(name->name, upperdir, name->len);
968 +               if (IS_ERR(newdentry)) {
969 +                       ovl_whiteout(upperdir, template);
970 +                       return newdentry;
971 +               }
972 +
973 +               /*
974 +                * Whiteout just been successfully removed, parent
975 +                * i_mutex is still held, there's no way the lookup
976 +                * could return positive.
977 +                */
978 +               WARN_ON(newdentry->d_inode);
979 +       }
980 +
981 +       return newdentry;
982 +
983 +out_dput:
984 +       dput(newdentry);
985 +       return ERR_PTR(err);
986 +}
987 +
988 +struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
989 +                               struct kstat *stat, const char *link)
990 +{
991 +       int err;
992 +       struct dentry *newdentry;
993 +       struct inode *dir = upperdir->d_inode;
994 +
995 +       newdentry = ovl_lookup_create(upperdir, dentry);
996 +       if (IS_ERR(newdentry))
997 +               goto out;
998 +
999 +       switch (stat->mode & S_IFMT) {
1000 +       case S_IFREG:
1001 +               err = vfs_create(dir, newdentry, stat->mode, NULL);
1002 +               break;
1003 +
1004 +       case S_IFDIR:
1005 +               err = vfs_mkdir(dir, newdentry, stat->mode);
1006 +               break;
1007 +
1008 +       case S_IFCHR:
1009 +       case S_IFBLK:
1010 +       case S_IFIFO:
1011 +       case S_IFSOCK:
1012 +               err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev);
1013 +               break;
1014 +
1015 +       case S_IFLNK:
1016 +               err = vfs_symlink(dir, newdentry, link);
1017 +               break;
1018 +
1019 +       default:
1020 +               err = -EPERM;
1021 +       }
1022 +       if (err) {
1023 +               if (ovl_dentry_is_opaque(dentry))
1024 +                       ovl_whiteout(upperdir, dentry);
1025 +               dput(newdentry);
1026 +               newdentry = ERR_PTR(err);
1027 +       } else if (WARN_ON(!newdentry->d_inode)) {
1028 +               /*
1029 +                * Not quite sure if non-instantiated dentry is legal or not.
1030 +                * VFS doesn't seem to care so check and warn here.
1031 +                */
1032 +               dput(newdentry);
1033 +               newdentry = ERR_PTR(-ENOENT);
1034 +       }
1035 +
1036 +out:
1037 +       return newdentry;
1038 +
1039 +}
1040 +
1041 +static int ovl_set_opaque(struct dentry *upperdentry)
1042 +{
1043 +       int err;
1044 +       const struct cred *old_cred;
1045 +       struct cred *override_cred;
1046 +
1047 +       override_cred = prepare_creds();
1048 +       if (!override_cred)
1049 +               return -ENOMEM;
1050 +
1051 +       /* CAP_SYS_ADMIN for setxattr of "trusted" namespace */
1052 +       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
1053 +       old_cred = override_creds(override_cred);
1054 +       err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
1055 +       revert_creds(old_cred);
1056 +       put_cred(override_cred);
1057 +
1058 +       return err;
1059 +}
1060 +
1061 +static int ovl_remove_opaque(struct dentry *upperdentry)
1062 +{
1063 +       int err;
1064 +       const struct cred *old_cred;
1065 +       struct cred *override_cred;
1066 +
1067 +       override_cred = prepare_creds();
1068 +       if (!override_cred)
1069 +               return -ENOMEM;
1070 +
1071 +       /* CAP_SYS_ADMIN for removexattr of "trusted" namespace */
1072 +       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
1073 +       old_cred = override_creds(override_cred);
1074 +       err = vfs_removexattr(upperdentry, ovl_opaque_xattr);
1075 +       revert_creds(old_cred);
1076 +       put_cred(override_cred);
1077 +
1078 +       return err;
1079 +}
1080 +
1081 +static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
1082 +                        struct kstat *stat)
1083 +{
1084 +       int err;
1085 +       enum ovl_path_type type;
1086 +       struct path realpath;
1087 +
1088 +       type = ovl_path_real(dentry, &realpath);
1089 +       err = vfs_getattr(&realpath, stat);
1090 +       if (err)
1091 +               return err;
1092 +
1093 +       stat->dev = dentry->d_sb->s_dev;
1094 +       stat->ino = dentry->d_inode->i_ino;
1095 +
1096 +       /*
1097 +        * It's probably not worth it to count subdirs to get the
1098 +        * correct link count.  nlink=1 seems to pacify 'find' and
1099 +        * other utilities.
1100 +        */
1101 +       if (type == OVL_PATH_MERGE)
1102 +               stat->nlink = 1;
1103 +
1104 +       return 0;
1105 +}
1106 +
1107 +static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
1108 +                            const char *link)
1109 +{
1110 +       int err;
1111 +       struct dentry *newdentry;
1112 +       struct dentry *upperdir;
1113 +       struct inode *inode;
1114 +       struct kstat stat = {
1115 +               .mode = mode,
1116 +               .rdev = rdev,
1117 +       };
1118 +
1119 +       err = -ENOMEM;
1120 +       inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
1121 +       if (!inode)
1122 +               goto out;
1123 +
1124 +       err = ovl_copy_up(dentry->d_parent);
1125 +       if (err)
1126 +               goto out_iput;
1127 +
1128 +       upperdir = ovl_dentry_upper(dentry->d_parent);
1129 +       mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
1130 +
1131 +       newdentry = ovl_upper_create(upperdir, dentry, &stat, link);
1132 +       err = PTR_ERR(newdentry);
1133 +       if (IS_ERR(newdentry))
1134 +               goto out_unlock;
1135 +
1136 +       ovl_dentry_version_inc(dentry->d_parent);
1137 +       if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) {
1138 +               err = ovl_set_opaque(newdentry);
1139 +               if (err) {
1140 +                       vfs_rmdir(upperdir->d_inode, newdentry);
1141 +                       ovl_whiteout(upperdir, dentry);
1142 +                       goto out_dput;
1143 +               }
1144 +       }
1145 +       ovl_dentry_update(dentry, newdentry);
1146 +       ovl_copyattr(newdentry->d_inode, inode);
1147 +       d_instantiate(dentry, inode);
1148 +       inode = NULL;
1149 +       newdentry = NULL;
1150 +       err = 0;
1151 +
1152 +out_dput:
1153 +       dput(newdentry);
1154 +out_unlock:
1155 +       mutex_unlock(&upperdir->d_inode->i_mutex);
1156 +out_iput:
1157 +       iput(inode);
1158 +out:
1159 +       return err;
1160 +}
1161 +
1162 +static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
1163 +                     bool excl)
1164 +{
1165 +       return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
1166 +}
1167 +
1168 +static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1169 +{
1170 +       return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
1171 +}
1172 +
1173 +static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
1174 +                    dev_t rdev)
1175 +{
1176 +       return ovl_create_object(dentry, mode, rdev, NULL);
1177 +}
1178 +
1179 +static int ovl_symlink(struct inode *dir, struct dentry *dentry,
1180 +                        const char *link)
1181 +{
1182 +       return ovl_create_object(dentry, S_IFLNK, 0, link);
1183 +}
1184 +
1185 +static int ovl_do_remove(struct dentry *dentry, bool is_dir)
1186 +{
1187 +       int err;
1188 +       enum ovl_path_type type;
1189 +       struct path realpath;
1190 +       struct dentry *upperdir;
1191 +
1192 +       err = ovl_copy_up(dentry->d_parent);
1193 +       if (err)
1194 +               return err;
1195 +
1196 +       upperdir = ovl_dentry_upper(dentry->d_parent);
1197 +       mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
1198 +       type = ovl_path_real(dentry, &realpath);
1199 +       if (type != OVL_PATH_LOWER) {
1200 +               err = -ESTALE;
1201 +               if (realpath.dentry->d_parent != upperdir)
1202 +                       goto out_d_drop;
1203 +
1204 +               /* FIXME: create whiteout up front and rename to target */
1205 +
1206 +               if (is_dir)
1207 +                       err = vfs_rmdir(upperdir->d_inode, realpath.dentry);
1208 +               else
1209 +                       err = vfs_unlink(upperdir->d_inode, realpath.dentry);
1210 +               if (err)
1211 +                       goto out_d_drop;
1212 +
1213 +               ovl_dentry_version_inc(dentry->d_parent);
1214 +       }
1215 +
1216 +       if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry))
1217 +               err = ovl_whiteout(upperdir, dentry);
1218 +
1219 +       /*
1220 +        * Keeping this dentry hashed would mean having to release
1221 +        * upperpath/lowerpath, which could only be done if we are the
1222 +        * sole user of this dentry.  Too tricky...  Just unhash for
1223 +        * now.
1224 +        */
1225 +out_d_drop:
1226 +       d_drop(dentry);
1227 +       mutex_unlock(&upperdir->d_inode->i_mutex);
1228 +
1229 +       return err;
1230 +}
1231 +
1232 +static int ovl_unlink(struct inode *dir, struct dentry *dentry)
1233 +{
1234 +       return ovl_do_remove(dentry, false);
1235 +}
1236 +
1237 +
1238 +static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
1239 +{
1240 +       int err;
1241 +       enum ovl_path_type type;
1242 +
1243 +       type = ovl_path_type(dentry);
1244 +       if (type != OVL_PATH_UPPER) {
1245 +               err = ovl_check_empty_and_clear(dentry, type);
1246 +               if (err)
1247 +                       return err;
1248 +       }
1249 +
1250 +       return ovl_do_remove(dentry, true);
1251 +}
1252 +
1253 +static int ovl_link(struct dentry *old, struct inode *newdir,
1254 +                   struct dentry *new)
1255 +{
1256 +       int err;
1257 +       struct dentry *olddentry;
1258 +       struct dentry *newdentry;
1259 +       struct dentry *upperdir;
1260 +       struct inode *newinode;
1261 +
1262 +       err = ovl_copy_up(old);
1263 +       if (err)
1264 +               goto out;
1265 +
1266 +       err = ovl_copy_up(new->d_parent);
1267 +       if (err)
1268 +               goto out;
1269 +
1270 +       upperdir = ovl_dentry_upper(new->d_parent);
1271 +       mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
1272 +       newdentry = ovl_lookup_create(upperdir, new);
1273 +       err = PTR_ERR(newdentry);
1274 +       if (IS_ERR(newdentry))
1275 +               goto out_unlock;
1276 +
1277 +       olddentry = ovl_dentry_upper(old);
1278 +       err = vfs_link(olddentry, upperdir->d_inode, newdentry);
1279 +       if (!err) {
1280 +               if (WARN_ON(!newdentry->d_inode)) {
1281 +                       dput(newdentry);
1282 +                       err = -ENOENT;
1283 +                       goto out_unlock;
1284 +               }
1285 +               newinode = ovl_new_inode(old->d_sb, newdentry->d_inode->i_mode,
1286 +                               new->d_fsdata);
1287 +               if (!newinode) {
1288 +                       err = -ENOMEM;
1289 +                       goto link_fail;
1290 +               }
1291 +               ovl_copyattr(upperdir->d_inode, newinode);
1292 +
1293 +               ovl_dentry_version_inc(new->d_parent);
1294 +               ovl_dentry_update(new, newdentry);
1295 +
1296 +               d_instantiate(new, newinode);
1297 +       } else {
1298 +link_fail:
1299 +               if (ovl_dentry_is_opaque(new))
1300 +                       ovl_whiteout(upperdir, new);
1301 +               dput(newdentry);
1302 +       }
1303 +out_unlock:
1304 +       mutex_unlock(&upperdir->d_inode->i_mutex);
1305 +out:
1306 +       return err;
1307 +}
1308 +
1309 +static int ovl_rename(struct inode *olddir, struct dentry *old,
1310 +                       struct inode *newdir, struct dentry *new)
1311 +{
1312 +       int err;
1313 +       enum ovl_path_type old_type;
1314 +       enum ovl_path_type new_type;
1315 +       struct dentry *old_upperdir;
1316 +       struct dentry *new_upperdir;
1317 +       struct dentry *olddentry;
1318 +       struct dentry *newdentry;
1319 +       struct dentry *trap;
1320 +       bool old_opaque;
1321 +       bool new_opaque;
1322 +       bool new_create = false;
1323 +       bool is_dir = S_ISDIR(old->d_inode->i_mode);
1324 +
1325 +       /* Don't copy up directory trees */
1326 +       old_type = ovl_path_type(old);
1327 +       if (old_type != OVL_PATH_UPPER && is_dir)
1328 +               return -EXDEV;
1329 +
1330 +       if (new->d_inode) {
1331 +               new_type = ovl_path_type(new);
1332 +
1333 +               if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
1334 +                       if (ovl_dentry_lower(old)->d_inode ==
1335 +                           ovl_dentry_lower(new)->d_inode)
1336 +                               return 0;
1337 +               }
1338 +               if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
1339 +                       if (ovl_dentry_upper(old)->d_inode ==
1340 +                           ovl_dentry_upper(new)->d_inode)
1341 +                               return 0;
1342 +               }
1343 +
1344 +               if (new_type != OVL_PATH_UPPER &&
1345 +                   S_ISDIR(new->d_inode->i_mode)) {
1346 +                       err = ovl_check_empty_and_clear(new, new_type);
1347 +                       if (err)
1348 +                               return err;
1349 +               }
1350 +       } else {
1351 +               new_type = OVL_PATH_UPPER;
1352 +       }
1353 +
1354 +       err = ovl_copy_up(old);
1355 +       if (err)
1356 +               return err;
1357 +
1358 +       err = ovl_copy_up(new->d_parent);
1359 +       if (err)
1360 +               return err;
1361 +
1362 +       old_upperdir = ovl_dentry_upper(old->d_parent);
1363 +       new_upperdir = ovl_dentry_upper(new->d_parent);
1364 +
1365 +       trap = lock_rename(new_upperdir, old_upperdir);
1366 +
1367 +       olddentry = ovl_dentry_upper(old);
1368 +       newdentry = ovl_dentry_upper(new);
1369 +       if (newdentry) {
1370 +               dget(newdentry);
1371 +       } else {
1372 +               new_create = true;
1373 +               newdentry = ovl_lookup_create(new_upperdir, new);
1374 +               err = PTR_ERR(newdentry);
1375 +               if (IS_ERR(newdentry))
1376 +                       goto out_unlock;
1377 +       }
1378 +
1379 +       err = -ESTALE;
1380 +       if (olddentry->d_parent != old_upperdir)
1381 +               goto out_dput;
1382 +       if (newdentry->d_parent != new_upperdir)
1383 +               goto out_dput;
1384 +       if (olddentry == trap)
1385 +               goto out_dput;
1386 +       if (newdentry == trap)
1387 +               goto out_dput;
1388 +
1389 +       old_opaque = ovl_dentry_is_opaque(old);
1390 +       new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER;
1391 +
1392 +       if (is_dir && !old_opaque && new_opaque) {
1393 +               err = ovl_set_opaque(olddentry);
1394 +               if (err)
1395 +                       goto out_dput;
1396 +       }
1397 +
1398 +       err = vfs_rename(old_upperdir->d_inode, olddentry,
1399 +                        new_upperdir->d_inode, newdentry);
1400 +
1401 +       if (err) {
1402 +               if (new_create && ovl_dentry_is_opaque(new))
1403 +                       ovl_whiteout(new_upperdir, new);
1404 +               if (is_dir && !old_opaque && new_opaque)
1405 +                       ovl_remove_opaque(olddentry);
1406 +               goto out_dput;
1407 +       }
1408 +
1409 +       if (old_type != OVL_PATH_UPPER || old_opaque)
1410 +               err = ovl_whiteout(old_upperdir, old);
1411 +       if (is_dir && old_opaque && !new_opaque)
1412 +               ovl_remove_opaque(olddentry);
1413 +
1414 +       if (old_opaque != new_opaque)
1415 +               ovl_dentry_set_opaque(old, new_opaque);
1416 +
1417 +       ovl_dentry_version_inc(old->d_parent);
1418 +       ovl_dentry_version_inc(new->d_parent);
1419 +
1420 +out_dput:
1421 +       dput(newdentry);
1422 +out_unlock:
1423 +       unlock_rename(new_upperdir, old_upperdir);
1424 +       return err;
1425 +}
1426 +
1427 +const struct inode_operations ovl_dir_inode_operations = {
1428 +       .lookup         = ovl_lookup,
1429 +       .mkdir          = ovl_mkdir,
1430 +       .symlink        = ovl_symlink,
1431 +       .unlink         = ovl_unlink,
1432 +       .rmdir          = ovl_rmdir,
1433 +       .rename         = ovl_rename,
1434 +       .link           = ovl_link,
1435 +       .setattr        = ovl_setattr,
1436 +       .create         = ovl_create,
1437 +       .mknod          = ovl_mknod,
1438 +       .permission     = ovl_permission,
1439 +       .getattr        = ovl_dir_getattr,
1440 +       .setxattr       = ovl_setxattr,
1441 +       .getxattr       = ovl_getxattr,
1442 +       .listxattr      = ovl_listxattr,
1443 +       .removexattr    = ovl_removexattr,
1444 +};
1445 --- /dev/null
1446 +++ b/fs/overlayfs/inode.c
1447 @@ -0,0 +1,372 @@
1448 +/*
1449 + *
1450 + * Copyright (C) 2011 Novell Inc.
1451 + *
1452 + * This program is free software; you can redistribute it and/or modify it
1453 + * under the terms of the GNU General Public License version 2 as published by
1454 + * the Free Software Foundation.
1455 + */
1456 +
1457 +#include <linux/fs.h>
1458 +#include <linux/slab.h>
1459 +#include <linux/xattr.h>
1460 +#include "overlayfs.h"
1461 +
1462 +int ovl_setattr(struct dentry *dentry, struct iattr *attr)
1463 +{
1464 +       struct dentry *upperdentry;
1465 +       int err;
1466 +
1467 +       if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry))
1468 +               err = ovl_copy_up_truncate(dentry, attr->ia_size);
1469 +       else
1470 +               err = ovl_copy_up(dentry);
1471 +       if (err)
1472 +               return err;
1473 +
1474 +       upperdentry = ovl_dentry_upper(dentry);
1475 +
1476 +       if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
1477 +               attr->ia_valid &= ~ATTR_MODE;
1478 +
1479 +       mutex_lock(&upperdentry->d_inode->i_mutex);
1480 +       err = notify_change(upperdentry, attr);
1481 +       if (!err)
1482 +               ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
1483 +       mutex_unlock(&upperdentry->d_inode->i_mutex);
1484 +
1485 +       return err;
1486 +}
1487 +
1488 +static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
1489 +                        struct kstat *stat)
1490 +{
1491 +       struct path realpath;
1492 +
1493 +       ovl_path_real(dentry, &realpath);
1494 +       return vfs_getattr(&realpath, stat);
1495 +}
1496 +
1497 +int ovl_permission(struct inode *inode, int mask)
1498 +{
1499 +       struct ovl_entry *oe;
1500 +       struct dentry *alias = NULL;
1501 +       struct inode *realinode;
1502 +       struct dentry *realdentry;
1503 +       bool is_upper;
1504 +       int err;
1505 +
1506 +       if (S_ISDIR(inode->i_mode)) {
1507 +               oe = inode->i_private;
1508 +       } else if (mask & MAY_NOT_BLOCK) {
1509 +               return -ECHILD;
1510 +       } else {
1511 +               /*
1512 +                * For non-directories find an alias and get the info
1513 +                * from there.
1514 +                */
1515 +               alias = d_find_any_alias(inode);
1516 +               if (WARN_ON(!alias))
1517 +                       return -ENOENT;
1518 +
1519 +               oe = alias->d_fsdata;
1520 +       }
1521 +
1522 +       realdentry = ovl_entry_real(oe, &is_upper);
1523 +
1524 +       /* Careful in RCU walk mode */
1525 +       realinode = ACCESS_ONCE(realdentry->d_inode);
1526 +       if (!realinode) {
1527 +               WARN_ON(!(mask & MAY_NOT_BLOCK));
1528 +               err = -ENOENT;
1529 +               goto out_dput;
1530 +       }
1531 +
1532 +       if (mask & MAY_WRITE) {
1533 +               umode_t mode = realinode->i_mode;
1534 +
1535 +               /*
1536 +                * Writes will always be redirected to upper layer, so
1537 +                * ignore lower layer being read-only.
1538 +                *
1539 +                * If the overlay itself is read-only then proceed
1540 +                * with the permission check, don't return EROFS.
1541 +                * This will only happen if this is the lower layer of
1542 +                * another overlayfs.
1543 +                *
1544 +                * If upper fs becomes read-only after the overlay was
1545 +                * constructed return EROFS to prevent modification of
1546 +                * upper layer.
1547 +                */
1548 +               err = -EROFS;
1549 +               if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
1550 +                   (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
1551 +                       goto out_dput;
1552 +       }
1553 +
1554 +       err = __inode_permission(realinode, mask);
1555 +out_dput:
1556 +       dput(alias);
1557 +       return err;
1558 +}
1559 +
1560 +
1561 +struct ovl_link_data {
1562 +       struct dentry *realdentry;
1563 +       void *cookie;
1564 +};
1565 +
1566 +static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
1567 +{
1568 +       void *ret;
1569 +       struct dentry *realdentry;
1570 +       struct inode *realinode;
1571 +
1572 +       realdentry = ovl_dentry_real(dentry);
1573 +       realinode = realdentry->d_inode;
1574 +
1575 +       if (WARN_ON(!realinode->i_op->follow_link))
1576 +               return ERR_PTR(-EPERM);
1577 +
1578 +       ret = realinode->i_op->follow_link(realdentry, nd);
1579 +       if (IS_ERR(ret))
1580 +               return ret;
1581 +
1582 +       if (realinode->i_op->put_link) {
1583 +               struct ovl_link_data *data;
1584 +
1585 +               data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
1586 +               if (!data) {
1587 +                       realinode->i_op->put_link(realdentry, nd, ret);
1588 +                       return ERR_PTR(-ENOMEM);
1589 +               }
1590 +               data->realdentry = realdentry;
1591 +               data->cookie = ret;
1592 +
1593 +               return data;
1594 +       } else {
1595 +               return NULL;
1596 +       }
1597 +}
1598 +
1599 +static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
1600 +{
1601 +       struct inode *realinode;
1602 +       struct ovl_link_data *data = c;
1603 +
1604 +       if (!data)
1605 +               return;
1606 +
1607 +       realinode = data->realdentry->d_inode;
1608 +       realinode->i_op->put_link(data->realdentry, nd, data->cookie);
1609 +       kfree(data);
1610 +}
1611 +
1612 +static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
1613 +{
1614 +       struct path realpath;
1615 +       struct inode *realinode;
1616 +
1617 +       ovl_path_real(dentry, &realpath);
1618 +       realinode = realpath.dentry->d_inode;
1619 +
1620 +       if (!realinode->i_op->readlink)
1621 +               return -EINVAL;
1622 +
1623 +       touch_atime(&realpath);
1624 +
1625 +       return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
1626 +}
1627 +
1628 +
1629 +static bool ovl_is_private_xattr(const char *name)
1630 +{
1631 +       return strncmp(name, "trusted.overlay.", 14) == 0;
1632 +}
1633 +
1634 +int ovl_setxattr(struct dentry *dentry, const char *name,
1635 +                const void *value, size_t size, int flags)
1636 +{
1637 +       int err;
1638 +       struct dentry *upperdentry;
1639 +
1640 +       if (ovl_is_private_xattr(name))
1641 +               return -EPERM;
1642 +
1643 +       err = ovl_copy_up(dentry);
1644 +       if (err)
1645 +               return err;
1646 +
1647 +       upperdentry = ovl_dentry_upper(dentry);
1648 +       return  vfs_setxattr(upperdentry, name, value, size, flags);
1649 +}
1650 +
1651 +ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
1652 +                    void *value, size_t size)
1653 +{
1654 +       if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
1655 +           ovl_is_private_xattr(name))
1656 +               return -ENODATA;
1657 +
1658 +       return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
1659 +}
1660 +
1661 +ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
1662 +{
1663 +       ssize_t res;
1664 +       int off;
1665 +
1666 +       res = vfs_listxattr(ovl_dentry_real(dentry), list, size);
1667 +       if (res <= 0 || size == 0)
1668 +               return res;
1669 +
1670 +       if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE)
1671 +               return res;
1672 +
1673 +       /* filter out private xattrs */
1674 +       for (off = 0; off < res;) {
1675 +               char *s = list + off;
1676 +               size_t slen = strlen(s) + 1;
1677 +
1678 +               BUG_ON(off + slen > res);
1679 +
1680 +               if (ovl_is_private_xattr(s)) {
1681 +                       res -= slen;
1682 +                       memmove(s, s + slen, res - off);
1683 +               } else {
1684 +                       off += slen;
1685 +               }
1686 +       }
1687 +
1688 +       return res;
1689 +}
1690 +
1691 +int ovl_removexattr(struct dentry *dentry, const char *name)
1692 +{
1693 +       int err;
1694 +       struct path realpath;
1695 +       enum ovl_path_type type;
1696 +
1697 +       if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
1698 +           ovl_is_private_xattr(name))
1699 +               return -ENODATA;
1700 +
1701 +       type = ovl_path_real(dentry, &realpath);
1702 +       if (type == OVL_PATH_LOWER) {
1703 +               err = vfs_getxattr(realpath.dentry, name, NULL, 0);
1704 +               if (err < 0)
1705 +                       return err;
1706 +
1707 +               err = ovl_copy_up(dentry);
1708 +               if (err)
1709 +                       return err;
1710 +
1711 +               ovl_path_upper(dentry, &realpath);
1712 +       }
1713 +
1714 +       return vfs_removexattr(realpath.dentry, name);
1715 +}
1716 +
1717 +static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
1718 +                                 struct dentry *realdentry)
1719 +{
1720 +       if (type != OVL_PATH_LOWER)
1721 +               return false;
1722 +
1723 +       if (special_file(realdentry->d_inode->i_mode))
1724 +               return false;
1725 +
1726 +       if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
1727 +               return false;
1728 +
1729 +       return true;
1730 +}
1731 +
1732 +static int ovl_dentry_open(struct dentry *dentry, struct file *file,
1733 +                   const struct cred *cred)
1734 +{
1735 +       int err;
1736 +       struct path realpath;
1737 +       enum ovl_path_type type;
1738 +
1739 +       type = ovl_path_real(dentry, &realpath);
1740 +       if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
1741 +               if (file->f_flags & O_TRUNC)
1742 +                       err = ovl_copy_up_truncate(dentry, 0);
1743 +               else
1744 +                       err = ovl_copy_up(dentry);
1745 +               if (err)
1746 +                       return err;
1747 +
1748 +               ovl_path_upper(dentry, &realpath);
1749 +       }
1750 +
1751 +       return vfs_open(&realpath, file, cred);
1752 +}
1753 +
1754 +static const struct inode_operations ovl_file_inode_operations = {
1755 +       .setattr        = ovl_setattr,
1756 +       .permission     = ovl_permission,
1757 +       .getattr        = ovl_getattr,
1758 +       .setxattr       = ovl_setxattr,
1759 +       .getxattr       = ovl_getxattr,
1760 +       .listxattr      = ovl_listxattr,
1761 +       .removexattr    = ovl_removexattr,
1762 +       .dentry_open    = ovl_dentry_open,
1763 +};
1764 +
1765 +static const struct inode_operations ovl_symlink_inode_operations = {
1766 +       .setattr        = ovl_setattr,
1767 +       .follow_link    = ovl_follow_link,
1768 +       .put_link       = ovl_put_link,
1769 +       .readlink       = ovl_readlink,
1770 +       .getattr        = ovl_getattr,
1771 +       .setxattr       = ovl_setxattr,
1772 +       .getxattr       = ovl_getxattr,
1773 +       .listxattr      = ovl_listxattr,
1774 +       .removexattr    = ovl_removexattr,
1775 +};
1776 +
1777 +struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
1778 +                           struct ovl_entry *oe)
1779 +{
1780 +       struct inode *inode;
1781 +
1782 +       inode = new_inode(sb);
1783 +       if (!inode)
1784 +               return NULL;
1785 +
1786 +       mode &= S_IFMT;
1787 +
1788 +       inode->i_ino = get_next_ino();
1789 +       inode->i_mode = mode;
1790 +       inode->i_flags |= S_NOATIME | S_NOCMTIME;
1791 +
1792 +       switch (mode) {
1793 +       case S_IFDIR:
1794 +               inode->i_private = oe;
1795 +               inode->i_op = &ovl_dir_inode_operations;
1796 +               inode->i_fop = &ovl_dir_operations;
1797 +               break;
1798 +
1799 +       case S_IFLNK:
1800 +               inode->i_op = &ovl_symlink_inode_operations;
1801 +               break;
1802 +
1803 +       case S_IFREG:
1804 +       case S_IFSOCK:
1805 +       case S_IFBLK:
1806 +       case S_IFCHR:
1807 +       case S_IFIFO:
1808 +               inode->i_op = &ovl_file_inode_operations;
1809 +               break;
1810 +
1811 +       default:
1812 +               WARN(1, "illegal file type: %i\n", mode);
1813 +               iput(inode);
1814 +               inode = NULL;
1815 +       }
1816 +
1817 +       return inode;
1818 +
1819 +}
1820 --- /dev/null
1821 +++ b/fs/overlayfs/overlayfs.h
1822 @@ -0,0 +1,70 @@
1823 +/*
1824 + *
1825 + * Copyright (C) 2011 Novell Inc.
1826 + *
1827 + * This program is free software; you can redistribute it and/or modify it
1828 + * under the terms of the GNU General Public License version 2 as published by
1829 + * the Free Software Foundation.
1830 + */
1831 +
1832 +struct ovl_entry;
1833 +
1834 +enum ovl_path_type {
1835 +       OVL_PATH_UPPER,
1836 +       OVL_PATH_MERGE,
1837 +       OVL_PATH_LOWER,
1838 +};
1839 +
1840 +extern const char *ovl_opaque_xattr;
1841 +extern const char *ovl_whiteout_xattr;
1842 +extern const struct dentry_operations ovl_dentry_operations;
1843 +
1844 +enum ovl_path_type ovl_path_type(struct dentry *dentry);
1845 +u64 ovl_dentry_version_get(struct dentry *dentry);
1846 +void ovl_dentry_version_inc(struct dentry *dentry);
1847 +void ovl_path_upper(struct dentry *dentry, struct path *path);
1848 +void ovl_path_lower(struct dentry *dentry, struct path *path);
1849 +enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
1850 +struct dentry *ovl_dentry_upper(struct dentry *dentry);
1851 +struct dentry *ovl_dentry_lower(struct dentry *dentry);
1852 +struct dentry *ovl_dentry_real(struct dentry *dentry);
1853 +struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
1854 +bool ovl_dentry_is_opaque(struct dentry *dentry);
1855 +void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
1856 +bool ovl_is_whiteout(struct dentry *dentry);
1857 +void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
1858 +struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
1859 +                         unsigned int flags);
1860 +struct file *ovl_path_open(struct path *path, int flags);
1861 +
1862 +struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
1863 +                               struct kstat *stat, const char *link);
1864 +
1865 +/* readdir.c */
1866 +extern const struct file_operations ovl_dir_operations;
1867 +int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type);
1868 +
1869 +/* inode.c */
1870 +int ovl_setattr(struct dentry *dentry, struct iattr *attr);
1871 +int ovl_permission(struct inode *inode, int mask);
1872 +int ovl_setxattr(struct dentry *dentry, const char *name,
1873 +                const void *value, size_t size, int flags);
1874 +ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
1875 +                    void *value, size_t size);
1876 +ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
1877 +int ovl_removexattr(struct dentry *dentry, const char *name);
1878 +
1879 +struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
1880 +                           struct ovl_entry *oe);
1881 +static inline void ovl_copyattr(struct inode *from, struct inode *to)
1882 +{
1883 +       to->i_uid = from->i_uid;
1884 +       to->i_gid = from->i_gid;
1885 +}
1886 +
1887 +/* dir.c */
1888 +extern const struct inode_operations ovl_dir_inode_operations;
1889 +
1890 +/* copy_up.c */
1891 +int ovl_copy_up(struct dentry *dentry);
1892 +int ovl_copy_up_truncate(struct dentry *dentry, loff_t size);
1893 --- /dev/null
1894 +++ b/fs/overlayfs/readdir.c
1895 @@ -0,0 +1,566 @@
1896 +/*
1897 + *
1898 + * Copyright (C) 2011 Novell Inc.
1899 + *
1900 + * This program is free software; you can redistribute it and/or modify it
1901 + * under the terms of the GNU General Public License version 2 as published by
1902 + * the Free Software Foundation.
1903 + */
1904 +
1905 +#include <linux/fs.h>
1906 +#include <linux/slab.h>
1907 +#include <linux/namei.h>
1908 +#include <linux/file.h>
1909 +#include <linux/xattr.h>
1910 +#include <linux/rbtree.h>
1911 +#include <linux/security.h>
1912 +#include <linux/cred.h>
1913 +#include "overlayfs.h"
1914 +
1915 +struct ovl_cache_entry {
1916 +       const char *name;
1917 +       unsigned int len;
1918 +       unsigned int type;
1919 +       u64 ino;
1920 +       bool is_whiteout;
1921 +       struct list_head l_node;
1922 +       struct rb_node node;
1923 +};
1924 +
1925 +struct ovl_readdir_data {
1926 +       struct rb_root *root;
1927 +       struct list_head *list;
1928 +       struct list_head *middle;
1929 +       struct dentry *dir;
1930 +       int count;
1931 +       int err;
1932 +};
1933 +
1934 +struct ovl_dir_file {
1935 +       bool is_real;
1936 +       bool is_cached;
1937 +       struct list_head cursor;
1938 +       u64 cache_version;
1939 +       struct list_head cache;
1940 +       struct file *realfile;
1941 +};
1942 +
1943 +static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
1944 +{
1945 +       return container_of(n, struct ovl_cache_entry, node);
1946 +}
1947 +
1948 +static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
1949 +                                                   const char *name, int len)
1950 +{
1951 +       struct rb_node *node = root->rb_node;
1952 +       int cmp;
1953 +
1954 +       while (node) {
1955 +               struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
1956 +
1957 +               cmp = strncmp(name, p->name, len);
1958 +               if (cmp > 0)
1959 +                       node = p->node.rb_right;
1960 +               else if (cmp < 0 || len < p->len)
1961 +                       node = p->node.rb_left;
1962 +               else
1963 +                       return p;
1964 +       }
1965 +
1966 +       return NULL;
1967 +}
1968 +
1969 +static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
1970 +                                                  u64 ino, unsigned int d_type)
1971 +{
1972 +       struct ovl_cache_entry *p;
1973 +
1974 +       p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL);
1975 +       if (p) {
1976 +               char *name_copy = (char *) (p + 1);
1977 +               memcpy(name_copy, name, len);
1978 +               name_copy[len] = '\0';
1979 +               p->name = name_copy;
1980 +               p->len = len;
1981 +               p->type = d_type;
1982 +               p->ino = ino;
1983 +               p->is_whiteout = false;
1984 +       }
1985 +
1986 +       return p;
1987 +}
1988 +
1989 +static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
1990 +                                 const char *name, int len, u64 ino,
1991 +                                 unsigned int d_type)
1992 +{
1993 +       struct rb_node **newp = &rdd->root->rb_node;
1994 +       struct rb_node *parent = NULL;
1995 +       struct ovl_cache_entry *p;
1996 +
1997 +       while (*newp) {
1998 +               int cmp;
1999 +               struct ovl_cache_entry *tmp;
2000 +
2001 +               parent = *newp;
2002 +               tmp = ovl_cache_entry_from_node(*newp);
2003 +               cmp = strncmp(name, tmp->name, len);
2004 +               if (cmp > 0)
2005 +                       newp = &tmp->node.rb_right;
2006 +               else if (cmp < 0 || len < tmp->len)
2007 +                       newp = &tmp->node.rb_left;
2008 +               else
2009 +                       return 0;
2010 +       }
2011 +
2012 +       p = ovl_cache_entry_new(name, len, ino, d_type);
2013 +       if (p == NULL)
2014 +               return -ENOMEM;
2015 +
2016 +       list_add_tail(&p->l_node, rdd->list);
2017 +       rb_link_node(&p->node, parent, newp);
2018 +       rb_insert_color(&p->node, rdd->root);
2019 +
2020 +       return 0;
2021 +}
2022 +
2023 +static int ovl_fill_lower(void *buf, const char *name, int namelen,
2024 +                           loff_t offset, u64 ino, unsigned int d_type)
2025 +{
2026 +       struct ovl_readdir_data *rdd = buf;
2027 +       struct ovl_cache_entry *p;
2028 +
2029 +       rdd->count++;
2030 +       p = ovl_cache_entry_find(rdd->root, name, namelen);
2031 +       if (p) {
2032 +               list_move_tail(&p->l_node, rdd->middle);
2033 +       } else {
2034 +               p = ovl_cache_entry_new(name, namelen, ino, d_type);
2035 +               if (p == NULL)
2036 +                       rdd->err = -ENOMEM;
2037 +               else
2038 +                       list_add_tail(&p->l_node, rdd->middle);
2039 +       }
2040 +
2041 +       return rdd->err;
2042 +}
2043 +
2044 +static void ovl_cache_free(struct list_head *list)
2045 +{
2046 +       struct ovl_cache_entry *p;
2047 +       struct ovl_cache_entry *n;
2048 +
2049 +       list_for_each_entry_safe(p, n, list, l_node)
2050 +               kfree(p);
2051 +
2052 +       INIT_LIST_HEAD(list);
2053 +}
2054 +
2055 +static int ovl_fill_upper(void *buf, const char *name, int namelen,
2056 +                         loff_t offset, u64 ino, unsigned int d_type)
2057 +{
2058 +       struct ovl_readdir_data *rdd = buf;
2059 +
2060 +       rdd->count++;
2061 +       return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
2062 +}
2063 +
2064 +static inline int ovl_dir_read(struct path *realpath,
2065 +                              struct ovl_readdir_data *rdd, filldir_t filler)
2066 +{
2067 +       struct file *realfile;
2068 +       int err;
2069 +
2070 +       realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
2071 +       if (IS_ERR(realfile))
2072 +               return PTR_ERR(realfile);
2073 +
2074 +       do {
2075 +               rdd->count = 0;
2076 +               rdd->err = 0;
2077 +               err = vfs_readdir(realfile, filler, rdd);
2078 +               if (err >= 0)
2079 +                       err = rdd->err;
2080 +       } while (!err && rdd->count);
2081 +       fput(realfile);
2082 +
2083 +       return 0;
2084 +}
2085 +
2086 +static void ovl_dir_reset(struct file *file)
2087 +{
2088 +       struct ovl_dir_file *od = file->private_data;
2089 +       enum ovl_path_type type = ovl_path_type(file->f_path.dentry);
2090 +
2091 +       if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) {
2092 +               list_del_init(&od->cursor);
2093 +               ovl_cache_free(&od->cache);
2094 +               od->is_cached = false;
2095 +       }
2096 +       WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
2097 +       if (od->is_real && type == OVL_PATH_MERGE) {
2098 +               fput(od->realfile);
2099 +               od->realfile = NULL;
2100 +               od->is_real = false;
2101 +       }
2102 +}
2103 +
2104 +static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd)
2105 +{
2106 +       struct ovl_cache_entry *p;
2107 +       struct dentry *dentry;
2108 +       const struct cred *old_cred;
2109 +       struct cred *override_cred;
2110 +
2111 +       override_cred = prepare_creds();
2112 +       if (!override_cred) {
2113 +               ovl_cache_free(rdd->list);
2114 +               return -ENOMEM;
2115 +       }
2116 +
2117 +       /*
2118 +        * CAP_SYS_ADMIN for getxattr
2119 +        * CAP_DAC_OVERRIDE for lookup
2120 +        */
2121 +       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
2122 +       cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
2123 +       old_cred = override_creds(override_cred);
2124 +
2125 +       mutex_lock(&rdd->dir->d_inode->i_mutex);
2126 +       list_for_each_entry(p, rdd->list, l_node) {
2127 +               if (p->type != DT_LNK)
2128 +                       continue;
2129 +
2130 +               dentry = lookup_one_len(p->name, rdd->dir, p->len);
2131 +               if (IS_ERR(dentry))
2132 +                       continue;
2133 +
2134 +               p->is_whiteout = ovl_is_whiteout(dentry);
2135 +               dput(dentry);
2136 +       }
2137 +       mutex_unlock(&rdd->dir->d_inode->i_mutex);
2138 +
2139 +       revert_creds(old_cred);
2140 +       put_cred(override_cred);
2141 +
2142 +       return 0;
2143 +}
2144 +
2145 +static inline int ovl_dir_read_merged(struct path *upperpath,
2146 +                                     struct path *lowerpath,
2147 +                                     struct ovl_readdir_data *rdd)
2148 +{
2149 +       int err;
2150 +       struct rb_root root = RB_ROOT;
2151 +       struct list_head middle;
2152 +
2153 +       rdd->root = &root;
2154 +       if (upperpath->dentry) {
2155 +               rdd->dir = upperpath->dentry;
2156 +               err = ovl_dir_read(upperpath, rdd, ovl_fill_upper);
2157 +               if (err)
2158 +                       goto out;
2159 +
2160 +               err = ovl_dir_mark_whiteouts(rdd);
2161 +               if (err)
2162 +                       goto out;
2163 +       }
2164 +       /*
2165 +        * Insert lowerpath entries before upperpath ones, this allows
2166 +        * offsets to be reasonably constant
2167 +        */
2168 +       list_add(&middle, rdd->list);
2169 +       rdd->middle = &middle;
2170 +       err = ovl_dir_read(lowerpath, rdd, ovl_fill_lower);
2171 +       list_del(&middle);
2172 +out:
2173 +       rdd->root = NULL;
2174 +
2175 +       return err;
2176 +}
2177 +
2178 +static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
2179 +{
2180 +       struct list_head *l;
2181 +       loff_t off;
2182 +
2183 +       l = od->cache.next;
2184 +       for (off = 0; off < pos; off++) {
2185 +               if (l == &od->cache)
2186 +                       break;
2187 +               l = l->next;
2188 +       }
2189 +       list_move_tail(&od->cursor, l);
2190 +}
2191 +
2192 +static int ovl_readdir(struct file *file, void *buf, filldir_t filler)
2193 +{
2194 +       struct ovl_dir_file *od = file->private_data;
2195 +       int res;
2196 +
2197 +       if (!file->f_pos)
2198 +               ovl_dir_reset(file);
2199 +
2200 +       if (od->is_real) {
2201 +               res = vfs_readdir(od->realfile, filler, buf);
2202 +               file->f_pos = od->realfile->f_pos;
2203 +
2204 +               return res;
2205 +       }
2206 +
2207 +       if (!od->is_cached) {
2208 +               struct path lowerpath;
2209 +               struct path upperpath;
2210 +               struct ovl_readdir_data rdd = { .list = &od->cache };
2211 +
2212 +               ovl_path_lower(file->f_path.dentry, &lowerpath);
2213 +               ovl_path_upper(file->f_path.dentry, &upperpath);
2214 +
2215 +               res = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
2216 +               if (res) {
2217 +                       ovl_cache_free(rdd.list);
2218 +                       return res;
2219 +               }
2220 +
2221 +               od->cache_version = ovl_dentry_version_get(file->f_path.dentry);
2222 +               od->is_cached = true;
2223 +
2224 +               ovl_seek_cursor(od, file->f_pos);
2225 +       }
2226 +
2227 +       while (od->cursor.next != &od->cache) {
2228 +               int over;
2229 +               loff_t off;
2230 +               struct ovl_cache_entry *p;
2231 +
2232 +               p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node);
2233 +               off = file->f_pos;
2234 +               if (!p->is_whiteout) {
2235 +                       over = filler(buf, p->name, p->len, off, p->ino,
2236 +                                     p->type);
2237 +                       if (over)
2238 +                               break;
2239 +               }
2240 +               file->f_pos++;
2241 +               list_move(&od->cursor, &p->l_node);
2242 +       }
2243 +
2244 +       return 0;
2245 +}
2246 +
2247 +static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
2248 +{
2249 +       loff_t res;
2250 +       struct ovl_dir_file *od = file->private_data;
2251 +
2252 +       mutex_lock(&file_inode(file)->i_mutex);
2253 +       if (!file->f_pos)
2254 +               ovl_dir_reset(file);
2255 +
2256 +       if (od->is_real) {
2257 +               res = vfs_llseek(od->realfile, offset, origin);
2258 +               file->f_pos = od->realfile->f_pos;
2259 +       } else {
2260 +               res = -EINVAL;
2261 +
2262 +               switch (origin) {
2263 +               case SEEK_CUR:
2264 +                       offset += file->f_pos;
2265 +                       break;
2266 +               case SEEK_SET:
2267 +                       break;
2268 +               default:
2269 +                       goto out_unlock;
2270 +               }
2271 +               if (offset < 0)
2272 +                       goto out_unlock;
2273 +
2274 +               if (offset != file->f_pos) {
2275 +                       file->f_pos = offset;
2276 +                       if (od->is_cached)
2277 +                               ovl_seek_cursor(od, offset);
2278 +               }
2279 +               res = offset;
2280 +       }
2281 +out_unlock:
2282 +       mutex_unlock(&file_inode(file)->i_mutex);
2283 +
2284 +       return res;
2285 +}
2286 +
2287 +static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
2288 +                        int datasync)
2289 +{
2290 +       struct ovl_dir_file *od = file->private_data;
2291 +
2292 +       /* May need to reopen directory if it got copied up */
2293 +       if (!od->realfile) {
2294 +               struct path upperpath;
2295 +
2296 +               ovl_path_upper(file->f_path.dentry, &upperpath);
2297 +               od->realfile = ovl_path_open(&upperpath, O_RDONLY);
2298 +               if (IS_ERR(od->realfile))
2299 +                       return PTR_ERR(od->realfile);
2300 +       }
2301 +
2302 +       return vfs_fsync_range(od->realfile, start, end, datasync);
2303 +}
2304 +
2305 +static int ovl_dir_release(struct inode *inode, struct file *file)
2306 +{
2307 +       struct ovl_dir_file *od = file->private_data;
2308 +
2309 +       list_del(&od->cursor);
2310 +       ovl_cache_free(&od->cache);
2311 +       if (od->realfile)
2312 +               fput(od->realfile);
2313 +       kfree(od);
2314 +
2315 +       return 0;
2316 +}
2317 +
2318 +static int ovl_dir_open(struct inode *inode, struct file *file)
2319 +{
2320 +       struct path realpath;
2321 +       struct file *realfile;
2322 +       struct ovl_dir_file *od;
2323 +       enum ovl_path_type type;
2324 +
2325 +       od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
2326 +       if (!od)
2327 +               return -ENOMEM;
2328 +
2329 +       type = ovl_path_real(file->f_path.dentry, &realpath);
2330 +       realfile = ovl_path_open(&realpath, file->f_flags);
2331 +       if (IS_ERR(realfile)) {
2332 +               kfree(od);
2333 +               return PTR_ERR(realfile);
2334 +       }
2335 +       INIT_LIST_HEAD(&od->cache);
2336 +       INIT_LIST_HEAD(&od->cursor);
2337 +       od->is_cached = false;
2338 +       od->realfile = realfile;
2339 +       od->is_real = (type != OVL_PATH_MERGE);
2340 +       file->private_data = od;
2341 +
2342 +       return 0;
2343 +}
2344 +
2345 +const struct file_operations ovl_dir_operations = {
2346 +       .read           = generic_read_dir,
2347 +       .open           = ovl_dir_open,
2348 +       .readdir        = ovl_readdir,
2349 +       .llseek         = ovl_dir_llseek,
2350 +       .fsync          = ovl_dir_fsync,
2351 +       .release        = ovl_dir_release,
2352 +};
2353 +
2354 +static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
2355 +{
2356 +       int err;
2357 +       struct path lowerpath;
2358 +       struct path upperpath;
2359 +       struct ovl_cache_entry *p;
2360 +       struct ovl_readdir_data rdd = { .list = list };
2361 +
2362 +       ovl_path_upper(dentry, &upperpath);
2363 +       ovl_path_lower(dentry, &lowerpath);
2364 +
2365 +       err = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
2366 +       if (err)
2367 +               return err;
2368 +
2369 +       err = 0;
2370 +
2371 +       list_for_each_entry(p, list, l_node) {
2372 +               if (p->is_whiteout)
2373 +                       continue;
2374 +
2375 +               if (p->name[0] == '.') {
2376 +                       if (p->len == 1)
2377 +                               continue;
2378 +                       if (p->len == 2 && p->name[1] == '.')
2379 +                               continue;
2380 +               }
2381 +               err = -ENOTEMPTY;
2382 +               break;
2383 +       }
2384 +
2385 +       return err;
2386 +}
2387 +
2388 +static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list)
2389 +{
2390 +       struct path upperpath;
2391 +       struct dentry *upperdir;
2392 +       struct ovl_cache_entry *p;
2393 +       const struct cred *old_cred;
2394 +       struct cred *override_cred;
2395 +       int err;
2396 +
2397 +       ovl_path_upper(dir, &upperpath);
2398 +       upperdir = upperpath.dentry;
2399 +
2400 +       override_cred = prepare_creds();
2401 +       if (!override_cred)
2402 +               return -ENOMEM;
2403 +
2404 +       /*
2405 +        * CAP_DAC_OVERRIDE for lookup and unlink
2406 +        * CAP_SYS_ADMIN for setxattr of "trusted" namespace
2407 +        * CAP_FOWNER for unlink in sticky directory
2408 +        */
2409 +       cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
2410 +       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
2411 +       cap_raise(override_cred->cap_effective, CAP_FOWNER);
2412 +       old_cred = override_creds(override_cred);
2413 +
2414 +       err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0);
2415 +       if (err)
2416 +               goto out_revert_creds;
2417 +
2418 +       mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
2419 +       list_for_each_entry(p, list, l_node) {
2420 +               struct dentry *dentry;
2421 +               int ret;
2422 +
2423 +               if (!p->is_whiteout)
2424 +                       continue;
2425 +
2426 +               dentry = lookup_one_len(p->name, upperdir, p->len);
2427 +               if (IS_ERR(dentry)) {
2428 +                       pr_warn(
2429 +                           "overlayfs: failed to lookup whiteout %.*s: %li\n",
2430 +                           p->len, p->name, PTR_ERR(dentry));
2431 +                       continue;
2432 +               }
2433 +               ret = vfs_unlink(upperdir->d_inode, dentry);
2434 +               dput(dentry);
2435 +               if (ret)
2436 +                       pr_warn(
2437 +                           "overlayfs: failed to unlink whiteout %.*s: %i\n",
2438 +                           p->len, p->name, ret);
2439 +       }
2440 +       mutex_unlock(&upperdir->d_inode->i_mutex);
2441 +
2442 +out_revert_creds:
2443 +       revert_creds(old_cred);
2444 +       put_cred(override_cred);
2445 +
2446 +       return err;
2447 +}
2448 +
2449 +int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type)
2450 +{
2451 +       int err;
2452 +       LIST_HEAD(list);
2453 +
2454 +       err = ovl_check_empty_dir(dentry, &list);
2455 +       if (!err && type == OVL_PATH_MERGE)
2456 +               err = ovl_remove_whiteouts(dentry, &list);
2457 +
2458 +       ovl_cache_free(&list);
2459 +
2460 +       return err;
2461 +}
2462 --- /dev/null
2463 +++ b/fs/overlayfs/super.c
2464 @@ -0,0 +1,685 @@
2465 +/*
2466 + *
2467 + * Copyright (C) 2011 Novell Inc.
2468 + *
2469 + * This program is free software; you can redistribute it and/or modify it
2470 + * under the terms of the GNU General Public License version 2 as published by
2471 + * the Free Software Foundation.
2472 + */
2473 +
2474 +#include <linux/fs.h>
2475 +#include <linux/namei.h>
2476 +#include <linux/xattr.h>
2477 +#include <linux/security.h>
2478 +#include <linux/mount.h>
2479 +#include <linux/slab.h>
2480 +#include <linux/parser.h>
2481 +#include <linux/module.h>
2482 +#include <linux/cred.h>
2483 +#include <linux/sched.h>
2484 +#include <linux/statfs.h>
2485 +#include <linux/seq_file.h>
2486 +#include "overlayfs.h"
2487 +
2488 +MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
2489 +MODULE_DESCRIPTION("Overlay filesystem");
2490 +MODULE_LICENSE("GPL");
2491 +
2492 +#define OVERLAYFS_SUPER_MAGIC 0x794c764f
2493 +
2494 +struct ovl_config {
2495 +       char *lowerdir;
2496 +       char *upperdir;
2497 +};
2498 +
2499 +/* private information held for overlayfs's superblock */
2500 +struct ovl_fs {
2501 +       struct vfsmount *upper_mnt;
2502 +       struct vfsmount *lower_mnt;
2503 +       long lower_namelen;
2504 +       /* pathnames of lower and upper dirs, for show_options */
2505 +       struct ovl_config config;
2506 +};
2507 +
2508 +/* private information held for every overlayfs dentry */
2509 +struct ovl_entry {
2510 +       /*
2511 +        * Keep "double reference" on upper dentries, so that
2512 +        * d_delete() doesn't think it's OK to reset d_inode to NULL.
2513 +        */
2514 +       struct dentry *__upperdentry;
2515 +       struct dentry *lowerdentry;
2516 +       union {
2517 +               struct {
2518 +                       u64 version;
2519 +                       bool opaque;
2520 +               };
2521 +               struct rcu_head rcu;
2522 +       };
2523 +};
2524 +
2525 +const char *ovl_whiteout_xattr = "trusted.overlay.whiteout";
2526 +const char *ovl_opaque_xattr = "trusted.overlay.opaque";
2527 +
2528 +
2529 +enum ovl_path_type ovl_path_type(struct dentry *dentry)
2530 +{
2531 +       struct ovl_entry *oe = dentry->d_fsdata;
2532 +
2533 +       if (oe->__upperdentry) {
2534 +               if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode))
2535 +                       return OVL_PATH_MERGE;
2536 +               else
2537 +                       return OVL_PATH_UPPER;
2538 +       } else {
2539 +               return OVL_PATH_LOWER;
2540 +       }
2541 +}
2542 +
2543 +static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
2544 +{
2545 +       struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
2546 +       smp_read_barrier_depends();
2547 +       return upperdentry;
2548 +}
2549 +
2550 +void ovl_path_upper(struct dentry *dentry, struct path *path)
2551 +{
2552 +       struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
2553 +       struct ovl_entry *oe = dentry->d_fsdata;
2554 +
2555 +       path->mnt = ofs->upper_mnt;
2556 +       path->dentry = ovl_upperdentry_dereference(oe);
2557 +}
2558 +
2559 +void ovl_path_lower(struct dentry *dentry, struct path *path)
2560 +{
2561 +       struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
2562 +       struct ovl_entry *oe = dentry->d_fsdata;
2563 +
2564 +       path->mnt = ofs->lower_mnt;
2565 +       path->dentry = oe->lowerdentry;
2566 +}
2567 +
2568 +enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
2569 +{
2570 +
2571 +       enum ovl_path_type type = ovl_path_type(dentry);
2572 +
2573 +       if (type == OVL_PATH_LOWER)
2574 +               ovl_path_lower(dentry, path);
2575 +       else
2576 +               ovl_path_upper(dentry, path);
2577 +
2578 +       return type;
2579 +}
2580 +
2581 +struct dentry *ovl_dentry_upper(struct dentry *dentry)
2582 +{
2583 +       struct ovl_entry *oe = dentry->d_fsdata;
2584 +
2585 +       return ovl_upperdentry_dereference(oe);
2586 +}
2587 +
2588 +struct dentry *ovl_dentry_lower(struct dentry *dentry)
2589 +{
2590 +       struct ovl_entry *oe = dentry->d_fsdata;
2591 +
2592 +       return oe->lowerdentry;
2593 +}
2594 +
2595 +struct dentry *ovl_dentry_real(struct dentry *dentry)
2596 +{
2597 +       struct ovl_entry *oe = dentry->d_fsdata;
2598 +       struct dentry *realdentry;
2599 +
2600 +       realdentry = ovl_upperdentry_dereference(oe);
2601 +       if (!realdentry)
2602 +               realdentry = oe->lowerdentry;
2603 +
2604 +       return realdentry;
2605 +}
2606 +
2607 +struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
2608 +{
2609 +       struct dentry *realdentry;
2610 +
2611 +       realdentry = ovl_upperdentry_dereference(oe);
2612 +       if (realdentry) {
2613 +               *is_upper = true;
2614 +       } else {
2615 +               realdentry = oe->lowerdentry;
2616 +               *is_upper = false;
2617 +       }
2618 +       return realdentry;
2619 +}
2620 +
2621 +bool ovl_dentry_is_opaque(struct dentry *dentry)
2622 +{
2623 +       struct ovl_entry *oe = dentry->d_fsdata;
2624 +       return oe->opaque;
2625 +}
2626 +
2627 +void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
2628 +{
2629 +       struct ovl_entry *oe = dentry->d_fsdata;
2630 +       oe->opaque = opaque;
2631 +}
2632 +
2633 +void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
2634 +{
2635 +       struct ovl_entry *oe = dentry->d_fsdata;
2636 +
2637 +       WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex));
2638 +       WARN_ON(oe->__upperdentry);
2639 +       BUG_ON(!upperdentry->d_inode);
2640 +       smp_wmb();
2641 +       oe->__upperdentry = dget(upperdentry);
2642 +}
2643 +
2644 +void ovl_dentry_version_inc(struct dentry *dentry)
2645 +{
2646 +       struct ovl_entry *oe = dentry->d_fsdata;
2647 +
2648 +       WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
2649 +       oe->version++;
2650 +}
2651 +
2652 +u64 ovl_dentry_version_get(struct dentry *dentry)
2653 +{
2654 +       struct ovl_entry *oe = dentry->d_fsdata;
2655 +
2656 +       WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
2657 +       return oe->version;
2658 +}
2659 +
2660 +bool ovl_is_whiteout(struct dentry *dentry)
2661 +{
2662 +       int res;
2663 +       char val;
2664 +
2665 +       if (!dentry)
2666 +               return false;
2667 +       if (!dentry->d_inode)
2668 +               return false;
2669 +       if (!S_ISLNK(dentry->d_inode->i_mode))
2670 +               return false;
2671 +
2672 +       res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1);
2673 +       if (res == 1 && val == 'y')
2674 +               return true;
2675 +
2676 +       return false;
2677 +}
2678 +
2679 +static bool ovl_is_opaquedir(struct dentry *dentry)
2680 +{
2681 +       int res;
2682 +       char val;
2683 +
2684 +       if (!S_ISDIR(dentry->d_inode->i_mode))
2685 +               return false;
2686 +
2687 +       res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1);
2688 +       if (res == 1 && val == 'y')
2689 +               return true;
2690 +
2691 +       return false;
2692 +}
2693 +
2694 +static void ovl_entry_free(struct rcu_head *head)
2695 +{
2696 +       struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu);
2697 +       kfree(oe);
2698 +}
2699 +
2700 +static void ovl_dentry_release(struct dentry *dentry)
2701 +{
2702 +       struct ovl_entry *oe = dentry->d_fsdata;
2703 +
2704 +       if (oe) {
2705 +               dput(oe->__upperdentry);
2706 +               dput(oe->__upperdentry);
2707 +               dput(oe->lowerdentry);
2708 +               call_rcu(&oe->rcu, ovl_entry_free);
2709 +       }
2710 +}
2711 +
2712 +const struct dentry_operations ovl_dentry_operations = {
2713 +       .d_release = ovl_dentry_release,
2714 +};
2715 +
2716 +static struct ovl_entry *ovl_alloc_entry(void)
2717 +{
2718 +       return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
2719 +}
2720 +
2721 +static inline struct dentry *ovl_lookup_real(struct dentry *dir,
2722 +                                            struct qstr *name)
2723 +{
2724 +       struct dentry *dentry;
2725 +
2726 +       mutex_lock(&dir->d_inode->i_mutex);
2727 +       dentry = lookup_one_len(name->name, dir, name->len);
2728 +       mutex_unlock(&dir->d_inode->i_mutex);
2729 +
2730 +       if (IS_ERR(dentry)) {
2731 +               if (PTR_ERR(dentry) == -ENOENT)
2732 +                       dentry = NULL;
2733 +       } else if (!dentry->d_inode) {
2734 +               dput(dentry);
2735 +               dentry = NULL;
2736 +       }
2737 +       return dentry;
2738 +}
2739 +
2740 +static int ovl_do_lookup(struct dentry *dentry)
2741 +{
2742 +       struct ovl_entry *oe;
2743 +       struct dentry *upperdir;
2744 +       struct dentry *lowerdir;
2745 +       struct dentry *upperdentry = NULL;
2746 +       struct dentry *lowerdentry = NULL;
2747 +       struct inode *inode = NULL;
2748 +       int err;
2749 +
2750 +       err = -ENOMEM;
2751 +       oe = ovl_alloc_entry();
2752 +       if (!oe)
2753 +               goto out;
2754 +
2755 +       upperdir = ovl_dentry_upper(dentry->d_parent);
2756 +       lowerdir = ovl_dentry_lower(dentry->d_parent);
2757 +
2758 +       if (upperdir) {
2759 +               upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
2760 +               err = PTR_ERR(upperdentry);
2761 +               if (IS_ERR(upperdentry))
2762 +                       goto out_put_dir;
2763 +
2764 +               if (lowerdir && upperdentry &&
2765 +                   (S_ISLNK(upperdentry->d_inode->i_mode) ||
2766 +                    S_ISDIR(upperdentry->d_inode->i_mode))) {
2767 +                       const struct cred *old_cred;
2768 +                       struct cred *override_cred;
2769 +
2770 +                       err = -ENOMEM;
2771 +                       override_cred = prepare_creds();
2772 +                       if (!override_cred)
2773 +                               goto out_dput_upper;
2774 +
2775 +                       /* CAP_SYS_ADMIN needed for getxattr */
2776 +                       cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
2777 +                       old_cred = override_creds(override_cred);
2778 +
2779 +                       if (ovl_is_opaquedir(upperdentry)) {
2780 +                               oe->opaque = true;
2781 +                       } else if (ovl_is_whiteout(upperdentry)) {
2782 +                               dput(upperdentry);
2783 +                               upperdentry = NULL;
2784 +                               oe->opaque = true;
2785 +                       }
2786 +                       revert_creds(old_cred);
2787 +                       put_cred(override_cred);
2788 +               }
2789 +       }
2790 +       if (lowerdir && !oe->opaque) {
2791 +               lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
2792 +               err = PTR_ERR(lowerdentry);
2793 +               if (IS_ERR(lowerdentry))
2794 +                       goto out_dput_upper;
2795 +       }
2796 +
2797 +       if (lowerdentry && upperdentry &&
2798 +           (!S_ISDIR(upperdentry->d_inode->i_mode) ||
2799 +            !S_ISDIR(lowerdentry->d_inode->i_mode))) {
2800 +               dput(lowerdentry);
2801 +               lowerdentry = NULL;
2802 +               oe->opaque = true;
2803 +       }
2804 +
2805 +       if (lowerdentry || upperdentry) {
2806 +               struct dentry *realdentry;
2807 +
2808 +               realdentry = upperdentry ? upperdentry : lowerdentry;
2809 +               err = -ENOMEM;
2810 +               inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
2811 +                                     oe);
2812 +               if (!inode)
2813 +                       goto out_dput;
2814 +               ovl_copyattr(realdentry->d_inode, inode);
2815 +       }
2816 +
2817 +       if (upperdentry)
2818 +               oe->__upperdentry = dget(upperdentry);
2819 +
2820 +       if (lowerdentry)
2821 +               oe->lowerdentry = lowerdentry;
2822 +
2823 +       dentry->d_fsdata = oe;
2824 +       dentry->d_op = &ovl_dentry_operations;
2825 +       d_add(dentry, inode);
2826 +
2827 +       return 0;
2828 +
2829 +out_dput:
2830 +       dput(lowerdentry);
2831 +out_dput_upper:
2832 +       dput(upperdentry);
2833 +out_put_dir:
2834 +       kfree(oe);
2835 +out:
2836 +       return err;
2837 +}
2838 +
2839 +struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
2840 +                         unsigned int flags)
2841 +{
2842 +       int err = ovl_do_lookup(dentry);
2843 +
2844 +       if (err)
2845 +               return ERR_PTR(err);
2846 +
2847 +       return NULL;
2848 +}
2849 +
2850 +struct file *ovl_path_open(struct path *path, int flags)
2851 +{
2852 +       return dentry_open(path, flags, current_cred());
2853 +}
2854 +
2855 +static void ovl_put_super(struct super_block *sb)
2856 +{
2857 +       struct ovl_fs *ufs = sb->s_fs_info;
2858 +
2859 +       if (!(sb->s_flags & MS_RDONLY))
2860 +               mnt_drop_write(ufs->upper_mnt);
2861 +
2862 +       mntput(ufs->upper_mnt);
2863 +       mntput(ufs->lower_mnt);
2864 +
2865 +       kfree(ufs->config.lowerdir);
2866 +       kfree(ufs->config.upperdir);
2867 +       kfree(ufs);
2868 +}
2869 +
2870 +static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data)
2871 +{
2872 +       int flags = *flagsp;
2873 +       struct ovl_fs *ufs = sb->s_fs_info;
2874 +
2875 +       /* When remounting rw or ro, we need to adjust the write access to the
2876 +        * upper fs.
2877 +        */
2878 +       if (((flags ^ sb->s_flags) & MS_RDONLY) == 0)
2879 +               /* No change to readonly status */
2880 +               return 0;
2881 +
2882 +       if (flags & MS_RDONLY) {
2883 +               mnt_drop_write(ufs->upper_mnt);
2884 +               return 0;
2885 +       } else
2886 +               return mnt_want_write(ufs->upper_mnt);
2887 +}
2888 +
2889 +/**
2890 + * ovl_statfs
2891 + * @sb: The overlayfs super block
2892 + * @buf: The struct kstatfs to fill in with stats
2893 + *
2894 + * Get the filesystem statistics.  As writes always target the upper layer
2895 + * filesystem pass the statfs to the same filesystem.
2896 + */
2897 +static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
2898 +{
2899 +       struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
2900 +       struct dentry *root_dentry = dentry->d_sb->s_root;
2901 +       struct path path;
2902 +       int err;
2903 +
2904 +       ovl_path_upper(root_dentry, &path);
2905 +
2906 +       err = vfs_statfs(&path, buf);
2907 +       if (!err) {
2908 +               buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
2909 +               buf->f_type = OVERLAYFS_SUPER_MAGIC;
2910 +       }
2911 +
2912 +       return err;
2913 +}
2914 +
2915 +/**
2916 + * ovl_show_options
2917 + *
2918 + * Prints the mount options for a given superblock.
2919 + * Returns zero; does not fail.
2920 + */
2921 +static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
2922 +{
2923 +       struct super_block *sb = dentry->d_sb;
2924 +       struct ovl_fs *ufs = sb->s_fs_info;
2925 +
2926 +       seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
2927 +       seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
2928 +       return 0;
2929 +}
2930 +
2931 +static const struct super_operations ovl_super_operations = {
2932 +       .put_super      = ovl_put_super,
2933 +       .remount_fs     = ovl_remount_fs,
2934 +       .statfs         = ovl_statfs,
2935 +       .show_options   = ovl_show_options,
2936 +};
2937 +
2938 +enum {
2939 +       OPT_LOWERDIR,
2940 +       OPT_UPPERDIR,
2941 +       OPT_ERR,
2942 +};
2943 +
2944 +static const match_table_t ovl_tokens = {
2945 +       {OPT_LOWERDIR,                  "lowerdir=%s"},
2946 +       {OPT_UPPERDIR,                  "upperdir=%s"},
2947 +       {OPT_ERR,                       NULL}
2948 +};
2949 +
2950 +static int ovl_parse_opt(char *opt, struct ovl_config *config)
2951 +{
2952 +       char *p;
2953 +
2954 +       config->upperdir = NULL;
2955 +       config->lowerdir = NULL;
2956 +
2957 +       while ((p = strsep(&opt, ",")) != NULL) {
2958 +               int token;
2959 +               substring_t args[MAX_OPT_ARGS];
2960 +
2961 +               if (!*p)
2962 +                       continue;
2963 +
2964 +               token = match_token(p, ovl_tokens, args);
2965 +               switch (token) {
2966 +               case OPT_UPPERDIR:
2967 +                       kfree(config->upperdir);
2968 +                       config->upperdir = match_strdup(&args[0]);
2969 +                       if (!config->upperdir)
2970 +                               return -ENOMEM;
2971 +                       break;
2972 +
2973 +               case OPT_LOWERDIR:
2974 +                       kfree(config->lowerdir);
2975 +                       config->lowerdir = match_strdup(&args[0]);
2976 +                       if (!config->lowerdir)
2977 +                               return -ENOMEM;
2978 +                       break;
2979 +
2980 +               default:
2981 +                       return -EINVAL;
2982 +               }
2983 +       }
2984 +       return 0;
2985 +}
2986 +
2987 +static int ovl_fill_super(struct super_block *sb, void *data, int silent)
2988 +{
2989 +       struct path lowerpath;
2990 +       struct path upperpath;
2991 +       struct inode *root_inode;
2992 +       struct dentry *root_dentry;
2993 +       struct ovl_entry *oe;
2994 +       struct ovl_fs *ufs;
2995 +       struct kstatfs statfs;
2996 +       int err;
2997 +
2998 +       err = -ENOMEM;
2999 +       ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
3000 +       if (!ufs)
3001 +               goto out;
3002 +
3003 +       err = ovl_parse_opt((char *) data, &ufs->config);
3004 +       if (err)
3005 +               goto out_free_ufs;
3006 +
3007 +       err = -EINVAL;
3008 +       if (!ufs->config.upperdir || !ufs->config.lowerdir) {
3009 +               pr_err("overlayfs: missing upperdir or lowerdir\n");
3010 +               goto out_free_config;
3011 +       }
3012 +
3013 +       oe = ovl_alloc_entry();
3014 +       if (oe == NULL)
3015 +               goto out_free_config;
3016 +
3017 +       err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath);
3018 +       if (err)
3019 +               goto out_free_oe;
3020 +
3021 +       err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
3022 +       if (err)
3023 +               goto out_put_upperpath;
3024 +
3025 +       err = -ENOTDIR;
3026 +       if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
3027 +           !S_ISDIR(lowerpath.dentry->d_inode->i_mode))
3028 +               goto out_put_lowerpath;
3029 +
3030 +       err = vfs_statfs(&lowerpath, &statfs);
3031 +       if (err) {
3032 +               pr_err("overlayfs: statfs failed on lowerpath\n");
3033 +               goto out_put_lowerpath;
3034 +       }
3035 +       ufs->lower_namelen = statfs.f_namelen;
3036 +
3037 +       sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
3038 +                               lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
3039 +
3040 +       err = -EINVAL;
3041 +       if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
3042 +               pr_err("overlayfs: maximum fs stacking depth exceeded\n");
3043 +               goto out_put_lowerpath;
3044 +       }
3045 +
3046 +
3047 +       ufs->upper_mnt = clone_private_mount(&upperpath);
3048 +       err = PTR_ERR(ufs->upper_mnt);
3049 +       if (IS_ERR(ufs->upper_mnt)) {
3050 +               pr_err("overlayfs: failed to clone upperpath\n");
3051 +               goto out_put_lowerpath;
3052 +       }
3053 +
3054 +       ufs->lower_mnt = clone_private_mount(&lowerpath);
3055 +       err = PTR_ERR(ufs->lower_mnt);
3056 +       if (IS_ERR(ufs->lower_mnt)) {
3057 +               pr_err("overlayfs: failed to clone lowerpath\n");
3058 +               goto out_put_upper_mnt;
3059 +       }
3060 +
3061 +       /*
3062 +        * Make lower_mnt R/O.  That way fchmod/fchown on lower file
3063 +        * will fail instead of modifying lower fs.
3064 +        */
3065 +       ufs->lower_mnt->mnt_flags |= MNT_READONLY;
3066 +
3067 +       /* If the upper fs is r/o, we mark overlayfs r/o too */
3068 +       if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
3069 +               sb->s_flags |= MS_RDONLY;
3070 +
3071 +       if (!(sb->s_flags & MS_RDONLY)) {
3072 +               err = mnt_want_write(ufs->upper_mnt);
3073 +               if (err)
3074 +                       goto out_put_lower_mnt;
3075 +       }
3076 +
3077 +       err = -ENOMEM;
3078 +       root_inode = ovl_new_inode(sb, S_IFDIR, oe);
3079 +       if (!root_inode)
3080 +               goto out_drop_write;
3081 +
3082 +       root_dentry = d_make_root(root_inode);
3083 +       if (!root_dentry)
3084 +               goto out_drop_write;
3085 +
3086 +       mntput(upperpath.mnt);
3087 +       mntput(lowerpath.mnt);
3088 +
3089 +       oe->__upperdentry = dget(upperpath.dentry);
3090 +       oe->lowerdentry = lowerpath.dentry;
3091 +
3092 +       root_dentry->d_fsdata = oe;
3093 +       root_dentry->d_op = &ovl_dentry_operations;
3094 +
3095 +       sb->s_magic = OVERLAYFS_SUPER_MAGIC;
3096 +       sb->s_op = &ovl_super_operations;
3097 +       sb->s_root = root_dentry;
3098 +       sb->s_fs_info = ufs;
3099 +
3100 +       return 0;
3101 +
3102 +out_drop_write:
3103 +       if (!(sb->s_flags & MS_RDONLY))
3104 +               mnt_drop_write(ufs->upper_mnt);
3105 +out_put_lower_mnt:
3106 +       mntput(ufs->lower_mnt);
3107 +out_put_upper_mnt:
3108 +       mntput(ufs->upper_mnt);
3109 +out_put_lowerpath:
3110 +       path_put(&lowerpath);
3111 +out_put_upperpath:
3112 +       path_put(&upperpath);
3113 +out_free_oe:
3114 +       kfree(oe);
3115 +out_free_config:
3116 +       kfree(ufs->config.lowerdir);
3117 +       kfree(ufs->config.upperdir);
3118 +out_free_ufs:
3119 +       kfree(ufs);
3120 +out:
3121 +       return err;
3122 +}
3123 +
3124 +static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
3125 +                               const char *dev_name, void *raw_data)
3126 +{
3127 +       return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
3128 +}
3129 +
3130 +static struct file_system_type ovl_fs_type = {
3131 +       .owner          = THIS_MODULE,
3132 +       .name           = "overlayfs",
3133 +       .mount          = ovl_mount,
3134 +       .kill_sb        = kill_anon_super,
3135 +};
3136 +MODULE_ALIAS_FS("overlayfs");
3137 +
3138 +static int __init ovl_init(void)
3139 +{
3140 +       return register_filesystem(&ovl_fs_type);
3141 +}
3142 +
3143 +static void __exit ovl_exit(void)
3144 +{
3145 +       unregister_filesystem(&ovl_fs_type);
3146 +}
3147 +
3148 +module_init(ovl_init);
3149 +module_exit(ovl_exit);
3150 --- a/fs/splice.c
3151 +++ b/fs/splice.c
3152 @@ -1313,6 +1313,7 @@ long do_splice_direct(struct file *in, l
3153  
3154         return ret;
3155  }
3156 +EXPORT_SYMBOL(do_splice_direct);
3157  
3158  static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
3159                                struct pipe_inode_info *opipe,
3160 --- a/include/linux/fs.h
3161 +++ b/include/linux/fs.h
3162 @@ -244,6 +244,12 @@ struct iattr {
3163   */
3164  #include <linux/quota.h>
3165  
3166 +/*
3167 + * Maximum number of layers of fs stack.  Needs to be limited to
3168 + * prevent kernel stack overflow
3169 + */
3170 +#define FILESYSTEM_MAX_STACK_DEPTH 2
3171 +
3172  /** 
3173   * enum positive_aop_returns - aop return codes with specific semantics
3174   *
3175 @@ -1322,6 +1328,11 @@ struct super_block {
3176  
3177         /* Being remounted read-only */
3178         int s_readonly_remount;
3179 +
3180 +       /*
3181 +        * Indicates how deep in a filesystem stack this SB is
3182 +        */
3183 +       int s_stack_depth;
3184  };
3185  
3186  /* superblock cache pruning functions */
3187 @@ -1575,6 +1586,7 @@ struct inode_operations {
3188         int (*atomic_open)(struct inode *, struct dentry *,
3189                            struct file *, unsigned open_flag,
3190                            umode_t create_mode, int *opened);
3191 +       int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
3192  } ____cacheline_aligned;
3193  
3194  ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
3195 @@ -2008,6 +2020,7 @@ extern struct file *file_open_name(struc
3196  extern struct file *filp_open(const char *, int, umode_t);
3197  extern struct file *file_open_root(struct dentry *, struct vfsmount *,
3198                                    const char *, int);
3199 +extern int vfs_open(const struct path *, struct file *, const struct cred *);
3200  extern struct file * dentry_open(const struct path *, int, const struct cred *);
3201  extern int filp_close(struct file *, fl_owner_t id);
3202  
3203 @@ -2208,6 +2221,7 @@ extern sector_t bmap(struct inode *, sec
3204  #endif
3205  extern int notify_change(struct dentry *, struct iattr *);
3206  extern int inode_permission(struct inode *, int);
3207 +extern int __inode_permission(struct inode *, int);
3208  extern int generic_permission(struct inode *, int);
3209  
3210  static inline bool execute_ok(struct inode *inode)
3211 @@ -2414,6 +2428,9 @@ extern ssize_t generic_file_splice_write
3212                 struct file *, loff_t *, size_t, unsigned int);
3213  extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
3214                 struct file *out, loff_t *, size_t len, unsigned int flags);
3215 +extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
3216 +               loff_t *opos, size_t len, unsigned int flags);
3217 +
3218  
3219  extern void
3220  file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
3221 --- a/include/linux/mount.h
3222 +++ b/include/linux/mount.h
3223 @@ -68,6 +68,9 @@ extern void mnt_pin(struct vfsmount *mnt
3224  extern void mnt_unpin(struct vfsmount *mnt);
3225  extern int __mnt_is_readonly(struct vfsmount *mnt);
3226  
3227 +struct path;
3228 +extern struct vfsmount *clone_private_mount(struct path *path);
3229 +
3230  struct file_system_type;
3231  extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
3232                                       int flags, const char *name,