projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| ef94b186 | 1 | config OVERLAY_FS |
| e9be9d5e | 2 | tristate "Overlay filesystem support" |
| 72d42504 | 3 | select EXPORTFS |
| e9be9d5e MS |
4 | help |
| 5 | An overlay filesystem combines two filesystems - an 'upper' filesystem | |
| 6 | and a 'lower' filesystem. When a name exists in both filesystems, the | |
| 7 | object in the 'upper' filesystem is visible while the object in the | |
| 8 | 'lower' filesystem is either hidden or, in the case of directories, | |
| 9 | merged with the 'upper' object. | |
| 10 | ||
| 11 | For more information see Documentation/filesystems/overlayfs.txt | |
| 688ea0e5 MS |
12 | |
| 13 | config OVERLAY_FS_REDIRECT_DIR | |
| 14 | bool "Overlayfs: turn on redirect dir feature by default" | |
| 15 | depends on OVERLAY_FS | |
| 16 | help | |
| 17 | If this config option is enabled then overlay filesystems will use | |
| 18 | redirects when renaming directories by default. In this case it is | |
| 19 | still possible to turn off redirects globally with the | |
| 20 | "redirect_dir=off" module option or on a filesystem instance basis | |
| 21 | with the "redirect_dir=off" mount option. | |
| 22 | ||
| 23 | Note, that redirects are not backward compatible. That is, mounting | |
| 24 | an overlay which has redirects on a kernel that doesn't support this | |
| 25 | feature will have unexpected results. | |
| 02bcd157 | 26 | |
| 438c84c2 MS |
27 | config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW |
| 28 | bool "Overlayfs: follow redirects even if redirects are turned off" | |
| 29 | default y | |
| 30 | depends on OVERLAY_FS | |
| 31 | help | |
| 32 | Disable this to get a possibly more secure configuration, but that | |
| 33 | might not be backward compatible with previous kernels. | |
| 34 | ||
| 35 | For more information, see Documentation/filesystems/overlayfs.txt | |
| 36 | ||
| 02bcd157 AG |
37 | config OVERLAY_FS_INDEX |
| 38 | bool "Overlayfs: turn on inodes index feature by default" | |
| 39 | depends on OVERLAY_FS | |
| 40 | help | |
| 41 | If this config option is enabled then overlay filesystems will use | |
| 42 | the inodes index dir to map lower inodes to upper inodes by default. | |
| 43 | In this case it is still possible to turn off index globally with the | |
| 44 | "index=off" module option or on a filesystem instance basis with the | |
| 45 | "index=off" mount option. | |
| 46 | ||
| 47 | The inodes index feature prevents breaking of lower hardlinks on copy | |
| 48 | up. | |
| 49 | ||
| 50 | Note, that the inodes index feature is read-only backward compatible. | |
| 51 | That is, mounting an overlay which has an index dir on a kernel that | |
| 52 | doesn't support this feature read-only, will not have any negative | |
| 53 | outcomes. However, mounting the same overlay with an old kernel | |
| 54 | read-write and then mounting it again with a new kernel, will have | |
| 55 | unexpected results. |