summaryrefslogtreecommitdiff
path: root/Documentation/filesystems
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-17 01:29:46 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-17 01:29:46 +0300
commit071a0578b0ce0b0e543d1e38ee6926b9cc21c198 (patch)
tree4e6bf57dc1b26ea7107237e6dcf8c70d12a9c1fb /Documentation/filesystems
parentfad70111d57e0b728b587eabc6f9f9b5240faa17 (diff)
parentbe4df0cea08a8b59eb38d73de988b7ba8022df41 (diff)
downloadlinux-071a0578b0ce0b0e543d1e38ee6926b9cc21c198.tar.xz
Merge tag 'ovl-update-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi: - Improve performance for certain container setups by introducing a "volatile" mode - ioctl improvements - continue preparation for unprivileged overlay mounts * tag 'ovl-update-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: use generic vfs_ioc_setflags_prepare() helper ovl: support [S|G]ETFLAGS and FS[S|G]ETXATTR ioctls for directories ovl: rearrange ovl_can_list() ovl: enumerate private xattrs ovl: pass ovl_fs down to functions accessing private xattrs ovl: drop flags argument from ovl_do_setxattr() ovl: adhere to the vfs_ vs. ovl_do_ conventions for xattrs ovl: use ovl_do_getxattr() for private xattr ovl: fold ovl_getxattr() into ovl_get_redirect_xattr() ovl: clean up ovl_getxattr() in copy_up.c duplicate ovl_getxattr() ovl: provide a mount option "volatile" ovl: check for incompatible features in work dir
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/overlayfs.rst19
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index 8ea83a51c266..580ab9a0fe31 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -564,6 +564,25 @@ Note: the mount options index=off,nfs_export=on are conflicting for a
read-write mount and will result in an error.
+Volatile mount
+--------------
+
+This is enabled with the "volatile" mount option. Volatile mounts are not
+guaranteed to survive a crash. It is strongly recommended that volatile
+mounts are only used if data written to the overlay can be recreated
+without significant effort.
+
+The advantage of mounting with the "volatile" option is that all forms of
+sync calls to the upper filesystem are omitted.
+
+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
+indicator that user should throw away upper and work directories and create
+fresh one. In very limited cases where the user knows that the system has
+not crashed and contents of upperdir are intact, The "volatile" directory
+can be removed.
+
Testsuite
---------