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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-04 10:01:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-04 10:01:17 -0800
commit4cb2c00c43b3fe88b32f29df4f76da1b92c33224 (patch)
tree7b517943d3d8b0a99649fc63a7580ffc12a25dad /Documentation
parent61556703b610a104de324e4f061dc6cf7b218b46 (diff)
parent335d3fc57941e5c6164c69d439aec1cb7a800876 (diff)
Merge tag 'ovl-fixes-5.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs fixes from Miklos Szeredi: - Fix capability conversion and minor overlayfs bugs that are related to the unprivileged overlay mounts introduced in this cycle. - Fix two recent (v5.10) and one old (v4.10) bug. - Clean up security xattr copy-up (related to a SELinux regression). * tag 'ovl-fixes-5.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: implement volatile-specific fsync error behaviour ovl: skip getxattr of security labels ovl: fix dentry leak in ovl_get_redirect ovl: avoid deadlock on directory ioctl cap: fix conversions on getxattr ovl: perform vfs_getxattr() with mounter creds ovl: add warning on user_ns mismatch
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/overlayfs.rst8
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index 587a93973929..78240e29b0bb 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -586,6 +586,14 @@ without significant effort.
The advantage of mounting with the "volatile" option is that all forms of
sync calls to the upper filesystem are omitted.
+In order to avoid a giving a false sense of safety, the syncfs (and fsync)
+semantics of volatile mounts are slightly different than that of the rest of
+VFS. If any writeback error occurs on the upperdir's filesystem after a
+volatile mount takes place, all sync functions will return an error. Once this
+condition is reached, the filesystem will not recover, and every subsequent sync
+call will return an error, even if the upperdir has not experience a new error
+since the last sync call.
+
When overlay is mounted with "volatile" option, the directory
"$workdir/work/incompat/volatile" is created. During next mount, overlay
checks for this directory and refuses to mount if present. This is a strong