125 lines
4.8 KiB
Plaintext
125 lines
4.8 KiB
Plaintext
config OVERLAY_FS
|
|
tristate "Overlay filesystem support"
|
|
select EXPORTFS
|
|
help
|
|
An overlay filesystem combines two filesystems - an 'upper' filesystem
|
|
and a 'lower' filesystem. When a name exists in both filesystems, the
|
|
object in the 'upper' filesystem is visible while the object in the
|
|
'lower' filesystem is either hidden or, in the case of directories,
|
|
merged with the 'upper' object.
|
|
|
|
For more information see Documentation/filesystems/overlayfs.txt
|
|
|
|
config OVERLAY_FS_REDIRECT_DIR
|
|
bool "Overlayfs: turn on redirect directory feature by default"
|
|
depends on OVERLAY_FS
|
|
help
|
|
If this config option is enabled then overlay filesystems will use
|
|
redirects when renaming directories by default. In this case it is
|
|
still possible to turn off redirects globally with the
|
|
"redirect_dir=off" module option or on a filesystem instance basis
|
|
with the "redirect_dir=off" mount option.
|
|
|
|
Note, that redirects are not backward compatible. That is, mounting
|
|
an overlay which has redirects on a kernel that doesn't support this
|
|
feature will have unexpected results.
|
|
|
|
If unsure, say N.
|
|
|
|
config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
|
|
bool "Overlayfs: follow redirects even if redirects are turned off"
|
|
default y
|
|
depends on OVERLAY_FS
|
|
help
|
|
Disable this to get a possibly more secure configuration, but that
|
|
might not be backward compatible with previous kernels.
|
|
|
|
If backward compatibility is not an issue, then it is safe and
|
|
recommended to say N here.
|
|
|
|
For more information, see Documentation/filesystems/overlayfs.txt
|
|
|
|
If unsure, say Y.
|
|
|
|
config OVERLAY_FS_INDEX
|
|
bool "Overlayfs: turn on inodes index feature by default"
|
|
depends on OVERLAY_FS
|
|
help
|
|
If this config option is enabled then overlay filesystems will use
|
|
the index directory to map lower inodes to upper inodes by default.
|
|
In this case it is still possible to turn off index globally with the
|
|
"index=off" module option or on a filesystem instance basis with the
|
|
"index=off" mount option.
|
|
|
|
The inodes index feature prevents breaking of lower hardlinks on copy
|
|
up.
|
|
|
|
Note, that the inodes index feature is not backward compatible.
|
|
That is, mounting an overlay which has an inodes index on a kernel
|
|
that doesn't support this feature will have unexpected results.
|
|
|
|
If unsure, say N.
|
|
|
|
config OVERLAY_FS_NFS_EXPORT
|
|
bool "Overlayfs: turn on NFS export feature by default"
|
|
depends on OVERLAY_FS
|
|
depends on OVERLAY_FS_INDEX
|
|
depends on !OVERLAY_FS_METACOPY
|
|
help
|
|
If this config option is enabled then overlay filesystems will use
|
|
the index directory to decode overlay NFS file handles by default.
|
|
In this case, it is still possible to turn off NFS export support
|
|
globally with the "nfs_export=off" module option or on a filesystem
|
|
instance basis with the "nfs_export=off" mount option.
|
|
|
|
The NFS export feature creates an index on copy up of every file and
|
|
directory. This full index is used to detect overlay filesystems
|
|
inconsistencies on lookup, like redirect from multiple upper dirs to
|
|
the same lower dir. The full index may incur some overhead on mount
|
|
time, especially when verifying that directory file handles are not
|
|
stale.
|
|
|
|
Note, that the NFS export feature is not backward compatible.
|
|
That is, mounting an overlay which has a full index on a kernel
|
|
that doesn't support this feature will have unexpected results.
|
|
|
|
Most users should say N here and enable this feature on a case-by-
|
|
case basis with the "nfs_export=on" mount option.
|
|
|
|
Say N unless you fully understand the consequences.
|
|
|
|
config OVERLAY_FS_XINO_AUTO
|
|
bool "Overlayfs: auto enable inode number mapping"
|
|
default n
|
|
depends on OVERLAY_FS
|
|
help
|
|
If this config option is enabled then overlay filesystems will use
|
|
unused high bits in undelying filesystem inode numbers to map all
|
|
inodes to a unified address space. The mapped 64bit inode numbers
|
|
might not be compatible with applications that expect 32bit inodes.
|
|
|
|
If compatibility with applications that expect 32bit inodes is not an
|
|
issue, then it is safe and recommended to say Y here.
|
|
|
|
For more information, see Documentation/filesystems/overlayfs.txt
|
|
|
|
If unsure, say N.
|
|
|
|
config OVERLAY_FS_METACOPY
|
|
bool "Overlayfs: turn on metadata only copy up feature by default"
|
|
depends on OVERLAY_FS
|
|
select OVERLAY_FS_REDIRECT_DIR
|
|
help
|
|
If this config option is enabled then overlay filesystems will
|
|
copy up only metadata where appropriate and data copy up will
|
|
happen when a file is opened for WRITE operation. It is still
|
|
possible to turn off this feature globally with the "metacopy=off"
|
|
module option or on a filesystem instance basis with the
|
|
"metacopy=off" mount option.
|
|
|
|
Note, that this feature is not backward compatible. That is,
|
|
mounting an overlay which has metacopy only inodes on a kernel
|
|
that doesn't support this feature will have unexpected results.
|
|
|
|
If unsure, say N.
|