1 # SPDX-License-Identifier: GPL-2.0-only <<
2 config OVERLAY_FS 1 config OVERLAY_FS
3 tristate "Overlay filesystem support" 2 tristate "Overlay filesystem support"
4 select FS_STACK <<
5 select EXPORTFS 3 select EXPORTFS
6 help 4 help
7 An overlay filesystem combines two f 5 An overlay filesystem combines two filesystems - an 'upper' filesystem
8 and a 'lower' filesystem. When a na 6 and a 'lower' filesystem. When a name exists in both filesystems, the
9 object in the 'upper' filesystem is 7 object in the 'upper' filesystem is visible while the object in the
10 'lower' filesystem is either hidden 8 'lower' filesystem is either hidden or, in the case of directories,
11 merged with the 'upper' object. 9 merged with the 'upper' object.
12 10
13 For more information see Documentati !! 11 For more information see Documentation/filesystems/overlayfs.txt
14 12
15 config OVERLAY_FS_REDIRECT_DIR 13 config OVERLAY_FS_REDIRECT_DIR
16 bool "Overlayfs: turn on redirect dire !! 14 bool "Overlayfs: turn on redirect dir feature by default"
17 depends on OVERLAY_FS 15 depends on OVERLAY_FS
18 help 16 help
19 If this config option is enabled the 17 If this config option is enabled then overlay filesystems will use
20 redirects when renaming directories 18 redirects when renaming directories by default. In this case it is
21 still possible to turn off redirects 19 still possible to turn off redirects globally with the
22 "redirect_dir=off" module option or 20 "redirect_dir=off" module option or on a filesystem instance basis
23 with the "redirect_dir=off" mount op 21 with the "redirect_dir=off" mount option.
24 22
25 Note, that redirects are not backwar 23 Note, that redirects are not backward compatible. That is, mounting
26 an overlay which has redirects on a 24 an overlay which has redirects on a kernel that doesn't support this
27 feature will have unexpected results 25 feature will have unexpected results.
28 26
29 If unsure, say N. <<
30 <<
31 config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW 27 config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
32 bool "Overlayfs: follow redirects even 28 bool "Overlayfs: follow redirects even if redirects are turned off"
33 default y 29 default y
34 depends on OVERLAY_FS 30 depends on OVERLAY_FS
35 help 31 help
36 Disable this to get a possibly more 32 Disable this to get a possibly more secure configuration, but that
37 might not be backward compatible wit 33 might not be backward compatible with previous kernels.
38 34
39 If backward compatibility is not an !! 35 For more information, see Documentation/filesystems/overlayfs.txt
40 recommended to say N here. <<
41 <<
42 For more information, see Documentat <<
43 <<
44 If unsure, say Y. <<
45 36
46 config OVERLAY_FS_INDEX 37 config OVERLAY_FS_INDEX
47 bool "Overlayfs: turn on inodes index 38 bool "Overlayfs: turn on inodes index feature by default"
48 depends on OVERLAY_FS 39 depends on OVERLAY_FS
49 help 40 help
50 If this config option is enabled the 41 If this config option is enabled then overlay filesystems will use
51 the index directory to map lower ino !! 42 the inodes index dir to map lower inodes to upper inodes by default.
52 In this case it is still possible to 43 In this case it is still possible to turn off index globally with the
53 "index=off" module option or on a fi 44 "index=off" module option or on a filesystem instance basis with the
54 "index=off" mount option. 45 "index=off" mount option.
55 46
56 The inodes index feature prevents br 47 The inodes index feature prevents breaking of lower hardlinks on copy
57 up. 48 up.
58 49
59 Note, that the inodes index feature !! 50 Note, that the inodes index feature is read-only backward compatible.
60 That is, mounting an overlay which h !! 51 That is, mounting an overlay which has an index dir on a kernel that
61 that doesn't support this feature wi !! 52 doesn't support this feature read-only, will not have any negative
62 !! 53 outcomes. However, mounting the same overlay with an old kernel
63 If unsure, say N. !! 54 read-write and then mounting it again with a new kernel, will have
64 !! 55 unexpected results.
65 config OVERLAY_FS_NFS_EXPORT <<
66 bool "Overlayfs: turn on NFS export fe <<
67 depends on OVERLAY_FS <<
68 depends on OVERLAY_FS_INDEX <<
69 depends on !OVERLAY_FS_METACOPY <<
70 help <<
71 If this config option is enabled the <<
72 the index directory to decode overla <<
73 In this case, it is still possible t <<
74 globally with the "nfs_export=off" m <<
75 instance basis with the "nfs_export= <<
76 <<
77 The NFS export feature creates an in <<
78 directory. This full index is used <<
79 inconsistencies on lookup, like redi <<
80 the same lower dir. The full index <<
81 time, especially when verifying that <<
82 stale. <<
83 <<
84 Note, that the NFS export feature is <<
85 That is, mounting an overlay which h <<
86 that doesn't support this feature wi <<
87 <<
88 Most users should say N here and ena <<
89 case basis with the "nfs_export=on" <<
90 <<
91 Say N unless you fully understand th <<
92 <<
93 config OVERLAY_FS_XINO_AUTO <<
94 bool "Overlayfs: auto enable inode num <<
95 default n <<
96 depends on OVERLAY_FS <<
97 depends on 64BIT <<
98 help <<
99 If this config option is enabled the <<
100 unused high bits in underlying files <<
101 inodes to a unified address space. <<
102 might not be compatible with applica <<
103 <<
104 If compatibility with applications t <<
105 issue, then it is safe and recommend <<
106 <<
107 For more information, see Documentat <<
108 <<
109 If unsure, say N. <<
110 <<
111 config OVERLAY_FS_METACOPY <<
112 bool "Overlayfs: turn on metadata only <<
113 depends on OVERLAY_FS <<
114 select OVERLAY_FS_REDIRECT_DIR <<
115 help <<
116 If this config option is enabled the <<
117 copy up only metadata where appropri <<
118 happen when a file is opened for WRI <<
119 possible to turn off this feature gl <<
120 module option or on a filesystem ins <<
121 "metacopy=off" mount option. <<
122 <<
123 Note, that this feature is not backw <<
124 mounting an overlay which has metaco <<
125 that doesn't support this feature wi <<
126 <<
127 If unsure, say N. <<
128 <<
129 config OVERLAY_FS_DEBUG <<
130 bool "Overlayfs: turn on extra debuggi <<
131 default n <<
132 depends on OVERLAY_FS <<
133 help <<
134 Say Y here to enable extra debugging <<
135 <<
136 If unsure, say N. <<
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