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Merge tag 'ovl-update-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

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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
This commit is contained in:
Linus Torvalds
2020-10-16 15:29:46 -07:00
parent fad70111d5 be4df0cea0
commit 071a0578b0
12 changed files with 446 additions and 200 deletions
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19
Documentation/filesystems/overlayfs.rst
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@@ -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
---------