Lines Matching +full:non +full:- +full:compliant
1 .. SPDX-License-Identifier: GPL-2.0
10 overlay-filesystem functionality in Linux (sometimes referred to as
11 union-filesystems). An overlay-filesystem tries to present a
17 ---------------
25 While directories will report an st_dev from the overlay-filesystem,
26 non-directory objects may report an st_dev from the lower filesystem or
29 over the lifetime of a non-directory object. Many applications and
35 make the overlay mount more compliant with filesystem scanners and
40 underlying filesystem, the same compliant behavior could be achieved
46 filesystem will fall back to the non xino behavior for that inode.
48 The "xino" feature can be enabled with the "-o xino=on" overlay mount option.
51 the lifetime of the filesystem. The "-o xino=auto" overlay mount option
60 +--------------+------------+------------+-----------------+----------------+
65 +--------------+-----+------+-----+------+--------+--------+--------+-------+
68 +--------------+-----+------+-----+------+--------+--------+--------+-------+
72 +--------------+-----+------+-----+------+--------+--------+--------+-------+
74 +--------------+-----+------+-----+------+--------+--------+--------+-------+
77 +--------------+-----+------+-----+------+--------+--------+--------+-------+
84 ---------------
86 An overlay filesystem combines two filesystems - an 'upper' filesystem
106 A read-only overlay of two read-only filesystems may use any
110 -----------
113 upper and lower filesystems and refers to a non-directory in either,
114 then the lower object is hidden - the name refers only to the upper
123 mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,\
141 --------------------------------
146 directories (non-directories are always opaque).
158 -------
162 obvious way (upper is read first, then lower - entries that already
163 exist are not re-added). This merged name list is cached in the
177 - read part of a directory
178 - remember an offset, and close the directory
179 - re-open the directory some time later
180 - seek to the remembered offset
190 --------------------
211 - OVERLAY_FS_REDIRECT_DIR:
213 - OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW:
221 - "redirect_dir=BOOL":
223 - "redirect_always_follow=BOOL":
225 - "redirect_max=NUM":
230 - "redirect_dir=on":
232 - "redirect_dir=follow":
234 - "redirect_dir=off":
237 - "redirect_dir=nofollow":
255 Non-directories
256 ---------------
258 Objects that are not directories (files, symlinks, device-special
261 the requires write-access, such as opening for write access, changing
263 to the upper filesystem (copy_up). Note that creating a hard-link
268 opened for read-write but the data is not modified.
271 exists in the upper filesystem - creating it and any parents as
273 mode, mtime, symlink-target etc.) and then if the object is a file, the
279 filesystem - future operations on the file are barely noticed by the
285 ----------------
293 3) non-mounting task MAY gain additional privileges through the overlay,
317 mount -t overlay overlay -olowerdir=/lower,upperdir=/upper,... /merged
321 cp -a /lower /upper
322 mount --bind /upper /merged
325 the time of copy (on-demand vs. up-front).
329 ---------------------
334 mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
337 that case the overlay will be read-only.
345 ---------------------
375 --------------------------
415 Non-standard behavior
416 ---------------------
418 Current version of overlayfs can act as a mostly POSIX compliant
426 b) If a file residing on a lower layer is opened for read-only and then
434 compliant filesystem:
442 will fail with EXDEV ("Invalid cross-device link").
471 ---------------------------------
504 ----------
512 non-directory object, the index entry is a hard link to the upper inode.
520 1. For a non-upper object, encode a lower file handle from lower inode
522 3. For a pure-upper object and for an existing non-indexed upper object,
526 - Header including path type information (e.g. lower/upper)
527 - UUID of the underlying filesystem
528 - Underlying filesystem encoding of underlying inode
540 5. For a non-directory, instantiate a disconnected overlay dentry from the
545 Decoding a non-directory file handle may return a disconnected dentry.
562 The overlay filesystem does not support non-directory connectable file
571 read-write mount and will result in an error.
580 --------------
608 ----------
610 The "-o userxattr" mount option forces overlayfs to use the
616 ---------
621 https://github.com/amir73il/unionmount-testsuite.git
625 # cd unionmount-testsuite
626 # ./run --ov --verify