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Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/overlayfs.rst | 19 |
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 --------- |