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TOMOYO Linux Cross Reference
Linux/fs/overlayfs/Kconfig

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Diff markup

Differences between /fs/overlayfs/Kconfig (Version linux-6.12-rc7) and /fs/overlayfs/Kconfig (Version linux-4.18.20)


  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 directory 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.                        27           If unsure, say N.
 30                                                    28 
 31 config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW           29 config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
 32         bool "Overlayfs: follow redirects even     30         bool "Overlayfs: follow redirects even if redirects are turned off"
 33         default y                                  31         default y
 34         depends on OVERLAY_FS                      32         depends on OVERLAY_FS
 35         help                                       33         help
 36           Disable this to get a possibly more      34           Disable this to get a possibly more secure configuration, but that
 37           might not be backward compatible wit     35           might not be backward compatible with previous kernels.
 38                                                    36 
 39           If backward compatibility is not an      37           If backward compatibility is not an issue, then it is safe and
 40           recommended to say N here.               38           recommended to say N here.
 41                                                    39 
 42           For more information, see Documentat !!  40           For more information, see Documentation/filesystems/overlayfs.txt
 43                                                    41 
 44           If unsure, say Y.                        42           If unsure, say Y.
 45                                                    43 
 46 config OVERLAY_FS_INDEX                            44 config OVERLAY_FS_INDEX
 47         bool "Overlayfs: turn on inodes index      45         bool "Overlayfs: turn on inodes index feature by default"
 48         depends on OVERLAY_FS                      46         depends on OVERLAY_FS
 49         help                                       47         help
 50           If this config option is enabled the     48           If this config option is enabled then overlay filesystems will use
 51           the index directory to map lower ino     49           the index directory to map lower inodes to upper inodes by default.
 52           In this case it is still possible to     50           In this case it is still possible to turn off index globally with the
 53           "index=off" module option or on a fi     51           "index=off" module option or on a filesystem instance basis with the
 54           "index=off" mount option.                52           "index=off" mount option.
 55                                                    53 
 56           The inodes index feature prevents br     54           The inodes index feature prevents breaking of lower hardlinks on copy
 57           up.                                      55           up.
 58                                                    56 
 59           Note, that the inodes index feature      57           Note, that the inodes index feature is not backward compatible.
 60           That is, mounting an overlay which h     58           That is, mounting an overlay which has an inodes index on a kernel
 61           that doesn't support this feature wi     59           that doesn't support this feature will have unexpected results.
 62                                                    60 
 63           If unsure, say N.                        61           If unsure, say N.
 64                                                    62 
 65 config OVERLAY_FS_NFS_EXPORT                       63 config OVERLAY_FS_NFS_EXPORT
 66         bool "Overlayfs: turn on NFS export fe     64         bool "Overlayfs: turn on NFS export feature by default"
 67         depends on OVERLAY_FS                      65         depends on OVERLAY_FS
 68         depends on OVERLAY_FS_INDEX                66         depends on OVERLAY_FS_INDEX
 69         depends on !OVERLAY_FS_METACOPY        << 
 70         help                                       67         help
 71           If this config option is enabled the     68           If this config option is enabled then overlay filesystems will use
 72           the index directory to decode overla     69           the index directory to decode overlay NFS file handles by default.
 73           In this case, it is still possible t     70           In this case, it is still possible to turn off NFS export support
 74           globally with the "nfs_export=off" m     71           globally with the "nfs_export=off" module option or on a filesystem
 75           instance basis with the "nfs_export=     72           instance basis with the "nfs_export=off" mount option.
 76                                                    73 
 77           The NFS export feature creates an in     74           The NFS export feature creates an index on copy up of every file and
 78           directory.  This full index is used      75           directory.  This full index is used to detect overlay filesystems
 79           inconsistencies on lookup, like redi     76           inconsistencies on lookup, like redirect from multiple upper dirs to
 80           the same lower dir.  The full index      77           the same lower dir.  The full index may incur some overhead on mount
 81           time, especially when verifying that     78           time, especially when verifying that directory file handles are not
 82           stale.                                   79           stale.
 83                                                    80 
 84           Note, that the NFS export feature is     81           Note, that the NFS export feature is not backward compatible.
 85           That is, mounting an overlay which h     82           That is, mounting an overlay which has a full index on a kernel
 86           that doesn't support this feature wi     83           that doesn't support this feature will have unexpected results.
 87                                                    84 
 88           Most users should say N here and ena     85           Most users should say N here and enable this feature on a case-by-
 89           case basis with the "nfs_export=on"      86           case basis with the "nfs_export=on" mount option.
 90                                                    87 
 91           Say N unless you fully understand th     88           Say N unless you fully understand the consequences.
 92                                                    89 
 93 config OVERLAY_FS_XINO_AUTO                        90 config OVERLAY_FS_XINO_AUTO
 94         bool "Overlayfs: auto enable inode num     91         bool "Overlayfs: auto enable inode number mapping"
 95         default n                                  92         default n
 96         depends on OVERLAY_FS                      93         depends on OVERLAY_FS
 97         depends on 64BIT                       << 
 98         help                                       94         help
 99           If this config option is enabled the     95           If this config option is enabled then overlay filesystems will use
100           unused high bits in underlying files !!  96           unused high bits in undelying filesystem inode numbers to map all
101           inodes to a unified address space.       97           inodes to a unified address space.  The mapped 64bit inode numbers
102           might not be compatible with applica     98           might not be compatible with applications that expect 32bit inodes.
103                                                    99 
104           If compatibility with applications t    100           If compatibility with applications that expect 32bit inodes is not an
105           issue, then it is safe and recommend    101           issue, then it is safe and recommended to say Y here.
106                                                   102 
107           For more information, see Documentat !! 103           For more information, see Documentation/filesystems/overlayfs.txt
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                                                   104 
136           If unsure, say N.                       105           If unsure, say N.
                                                      

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