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Diffstat (limited to 'fs/overlayfs/Kconfig')
| -rw-r--r-- | fs/overlayfs/Kconfig | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig new file mode 100644 index 000000000..dd188c799 --- /dev/null +++ b/fs/overlayfs/Kconfig @@ -0,0 +1,126 @@ +# SPDX-License-Identifier: GPL-2.0-only +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.rst + +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.rst + + 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 + depends on 64BIT + 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.rst + + 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. |