From: Roman Yeryomin Date: Fri, 15 Dec 2017 14:10:30 +0000 (+0200) Subject: overlay: fix race condition when switching to jffs2 X-Git-Url: http://git.archive.openwrt.org/?p=project%2Ffstools.git;a=commitdiff_plain;h=11efbf3b90f031ce634fc38cad07a4aef2985777;hp=bdeb95a849913bfe2c0eff5d03857c79a4c7d66d overlay: fix race condition when switching to jffs2 There is a race between `cp -a /tmp/root/* /rom/overlay` from libfstools/overlay.c and a process creating new file(s) before pivot(/rom, /mnt) occured. That is a process can create a file and it will not be copied. To workaround this, do additional copy after jffs2 is ready. This doesn't completely solve the problem but since there was no other fix provided since original RFC [1], it is better than nothiing. [1] https://www.mail-archive.com/openwrt-devel@lists.openwrt.org/msg38218.html Signed-off-by: Roman Yeryomin --- diff --git a/libfstools/overlay.c b/libfstools/overlay.c index 7ada5ff..8423a57 100644 --- a/libfstools/overlay.c +++ b/libfstools/overlay.c @@ -243,6 +243,10 @@ jffs2_switch(struct volume *v) ULOG_INFO("performing overlay whiteout\n"); umount2("/tmp/root", MNT_DETACH); foreachdir("/overlay/", handle_whiteout); + + /* try hard to be in sync */ + ULOG_INFO("syncronizing overlay\n"); + system("cp -a /tmp/root/upper/* / 2>/dev/null"); break; case FS_EXT4: