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 AG |
26 | |
27 | config OVERLAY_FS_INDEX | |
28 | bool "Overlayfs: turn on inodes index feature by default" | |
29 | depends on OVERLAY_FS | |
30 | help | |
31 | If this config option is enabled then overlay filesystems will use | |
32 | the inodes index dir to map lower inodes to upper inodes by default. | |
33 | In this case it is still possible to turn off index globally with the | |
34 | "index=off" module option or on a filesystem instance basis with the | |
35 | "index=off" mount option. | |
36 | ||
37 | The inodes index feature prevents breaking of lower hardlinks on copy | |
38 | up. | |
39 | ||
40 | Note, that the inodes index feature is read-only backward compatible. | |
41 | That is, mounting an overlay which has an index dir on a kernel that | |
42 | doesn't support this feature read-only, will not have any negative | |
43 | outcomes. However, mounting the same overlay with an old kernel | |
44 | read-write and then mounting it again with a new kernel, will have | |
45 | unexpected results. |