Lines Matching refs:overlay
10 overlay-filesystem functionality in Linux (sometimes referred to as
11 union-filesystems). An overlay-filesystem tries to present a
19 The overlay filesystem approach is 'hybrid', because the objects that
25 While directories will report an st_dev from the overlay-filesystem,
32 In the special case of all overlay layers on the same underlying
33 filesystem, all objects will report an st_dev from the overlay
35 make the overlay mount more compliant with filesystem scanners and
36 overlay objects will be distinguishable from the corresponding
39 On 64bit systems, even if all overlay layers are not on the same
45 handles with 32bit inode number encoding (e.g. ext4), overlay filesystem
48 feature with the "-o xino=on" overlay mount option. That is useful for the
51 the underlying inode number does overflow into the high xino bits, overlay
54 The following table summarizes what can be expected in different overlay
88 An overlay filesystem combines two filesystems - an 'upper' filesystem
106 A read-only overlay of two read-only filesystems may use any
123 mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,\
131 is cached in the dentry belonging to the overlay filesystem. If both
144 filesystem, an overlay filesystem needs to record in the upper filesystem
153 A directory is made opaque by setting the xattr "trusted.overlay.opaque"
202 copied up (but not the contents). Then the "trusted.overlay.redirect"
204 root of the overlay. Finally the directory is moved to the new
219 Module options (can also be changed through /sys/module/overlay/parameters/):
243 upper directory is stored in a "trusted.overlay.upper" extended attribute
251 NFS export support on an overlay filesystem with no upper layer requires
277 Once the copy_up is complete, the overlay filesystem simply
280 overlay filesystem (though an operation on the name of the file such as
287 Permission checking in the overlay filesystem follows these principles:
291 2) task creating the overlay mount MUST NOT gain additional privileges
293 3) non-mounting task MAY gain additional privileges through the overlay,
317 mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,... /merged
334 mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
337 that case the overlay will be read-only.
377 Lower layers may be shared among several overlay mounts and that is indeed
378 a very common practice. An overlay mount may use the same lower layer
379 path as another overlay mount and it may use a lower layer path that is
380 beneath or above the path of another overlay lower layer path.
383 another overlay mount is not allowed and may fail with EBUSY. Using
386 upper layer and/or workdir path the behavior of the overlay is undefined,
389 Mounting an overlay using an upper layer path, where the upper layer path
390 was previously used by another mounted overlay in combination with a
396 filesystem, are encoded and stored in the "trusted.overlay.origin" extended
409 It is quite a common practice to copy overlay layers to a different
455 underlying filesystem for all layers making up the overlay.
462 overlay filesystem and the value of st_ino for directory objects may not be
463 persistent and could change even while the overlay filesystem is mounted, as
470 Offline changes, when the overlay is not mounted, are allowed to either
473 Changes to the underlying filesystems while part of a mounted overlay
475 the behavior of the overlay is undefined, though it will not result in
478 When the overlay NFS export feature is enabled, overlay filesystems
484 attribute "trusted.overlay.origin" on the upper inode.
488 to by the "trusted.overlay.redirect" extended attribute, will verify
500 feature is enabled, an overlay filesystem may be exported to NFS.
507 "trusted.overlay.upper" with an encoded file handle of the upper
510 When encoding a file handle from an overlay filesystem object, the
518 The encoded overlay file handle includes:
524 are stored in extended attribute "trusted.overlay.origin".
526 When decoding an overlay file handle, the following steps are followed:
532 overlay object that was deleted after its file handle was encoded.
533 5. For a non-directory, instantiate a disconnected overlay dentry from the
536 and index, to lookup a connected overlay dentry.
542 When overlay filesystem has multiple lower layers, a middle layer
548 reconstruct a connected overlay path. To mitigate the cases of
551 On an overlay filesystem with no upper layer this mitigation cannot be
555 The overlay filesystem does not support non-directory connectable file
572 mounts are only used if data written to the overlay can be recreated
578 When overlay is mounted with "volatile" option, the directory
579 "$workdir/work/incompat/volatile" is created. During next mount, overlay