1 # SPDX-License-Identifier: GPL-2.0-only
2 config OVERLAY_FS
3 tristate "Overlay filesystem support"
4 select FS_STACK
5 select EXPORTFS
6 help
7 An overlay filesystem combines two f
8 and a 'lower' filesystem. When a na
9 object in the 'upper' filesystem is
10 'lower' filesystem is either hidden
11 merged with the 'upper' object.
12
13 For more information see Documentati
14
15 config OVERLAY_FS_REDIRECT_DIR
16 bool "Overlayfs: turn on redirect dire
17 depends on OVERLAY_FS
18 help
19 If this config option is enabled the
20 redirects when renaming directories
21 still possible to turn off redirects
22 "redirect_dir=off" module option or
23 with the "redirect_dir=off" mount op
24
25 Note, that redirects are not backwar
26 an overlay which has redirects on a
27 feature will have unexpected results
28
29 If unsure, say N.
30
31 config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
32 bool "Overlayfs: follow redirects even
33 default y
34 depends on OVERLAY_FS
35 help
36 Disable this to get a possibly more
37 might not be backward compatible wit
38
39 If backward compatibility is not an
40 recommended to say N here.
41
42 For more information, see Documentat
43
44 If unsure, say Y.
45
46 config OVERLAY_FS_INDEX
47 bool "Overlayfs: turn on inodes index
48 depends on OVERLAY_FS
49 help
50 If this config option is enabled the
51 the index directory to map lower ino
52 In this case it is still possible to
53 "index=off" module option or on a fi
54 "index=off" mount option.
55
56 The inodes index feature prevents br
57 up.
58
59 Note, that the inodes index feature
60 That is, mounting an overlay which h
61 that doesn't support this feature wi
62
63 If unsure, say N.
64
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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