linux/Documentation/filesystems
Linus Torvalds 5dfbfe71e3 fs.idmapped.v5.17
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Merge tag 'fs.idmapped.v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull fs idmapping updates from Christian Brauner:
 "This contains the work to enable the idmapping infrastructure to
  support idmapped mounts of filesystems mounted with an idmapping.

  In addition this contains various cleanups that avoid repeated
  open-coding of the same functionality and simplify the code in quite a
  few places.

  We also finish the renaming of the mapping helpers we started a few
  kernel releases back and move them to a dedicated header to not
  continue polluting the fs header needlessly with low-level idmapping
  helpers. With this series the fs header only contains idmapping
  helpers that interact with fs objects.

  Currently we only support idmapped mounts for filesystems mounted
  without an idmapping themselves. This was a conscious decision
  mentioned in multiple places (cf. [1]).

  As explained at length in [3] it is perfectly fine to extend support
  for idmapped mounts to filesystem's mounted with an idmapping should
  the need arise. The need has been there for some time now (cf. [2]).

  Before we can port any filesystem that is mountable with an idmapping
  to support idmapped mounts in the coming cycles, we need to first
  extend the mapping helpers to account for the filesystem's idmapping.
  This again, is explained at length in our documentation at [3] and
  also in the individual commit messages so here's an overview.

  Currently, the low-level mapping helpers implement the remapping
  algorithms described in [3] in a simplified manner as we could rely on
  the fact that all filesystems supporting idmapped mounts are mounted
  without an idmapping.

  In contrast, filesystems mounted with an idmapping are very likely to
  not use an identity mapping and will instead use a non-identity
  mapping. So the translation step from or into the filesystem's
  idmapping in the remapping algorithm cannot be skipped for such
  filesystems.

  Non-idmapped filesystems and filesystems not supporting idmapped
  mounts are unaffected by this change as the remapping algorithms can
  take the same shortcut as before. If the low-level helpers detect that
  they are dealing with an idmapped mount but the underlying filesystem
  is mounted without an idmapping we can rely on the previous shortcut
  and can continue to skip the translation step from or into the
  filesystem's idmapping. And of course, if the low-level helpers detect
  that they are not dealing with an idmapped mount they can simply
  return the relevant id unchanged; no remapping needs to be performed
  at all.

  These checks guarantee that only the minimal amount of work is
  performed. As before, if idmapped mounts aren't used the low-level
  helpers are idempotent and no work is performed at all"

Link: 2ca4dcc490 ("fs/mount_setattr: tighten permission checks") [1]
Link: https://github.com/containers/podman/issues/10374 [2]
Link: Documentations/filesystems/idmappings.rst [3]
Link: a65e58e791 ("fs: document and rename fsid helpers") [4]

* tag 'fs.idmapped.v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  fs: support mapped mounts of mapped filesystems
  fs: add i_user_ns() helper
  fs: port higher-level mapping helpers
  fs: remove unused low-level mapping helpers
  fs: use low-level mapping helpers
  docs: update mapping documentation
  fs: account for filesystem mappings
  fs: tweak fsuidgid_has_mapping()
  fs: move mapping helpers
  fs: add is_idmapped_mnt() helper
2022-01-11 14:26:55 -08:00
..
caching docs: filesystems: Replace HTTP links with HTTPS ones 2020-07-13 09:33:22 -06:00
cifs docs: filesystem: cifs: ksmbd: Fix small layout issues 2021-11-25 00:09:26 -06:00
ext4 ext4: docs: Take out unneeded escaping 2021-10-07 08:46:02 -06:00
nfs nfs: reexport documentation 2021-09-21 17:51:47 -04:00
spufs
9p.rst Replace HTTP links with HTTPS ones: 9P FILE SYSTEM 2020-07-13 11:28:12 -06:00
adfs.rst
affs.rst affs: fix basic permission bits to actually work 2020-08-31 12:20:31 +02:00
afs.rst AFS: Documentation: fix a few typos in afs.rst 2021-01-21 14:06:00 -07:00
api-summary.rst block: move fs/block_dev.c to block/bdev.c 2021-09-07 08:39:40 -06:00
autofs-mount-control.rst
autofs.rst docs: filesystems: Fix grammatical error "with" to "which" 2021-11-15 02:54:37 -07:00
automount-support.rst
befs.rst
bfs.rst
btrfs.rst
ceph.rst libceph, rbd, ceph: "blacklist" -> "blocklist" 2020-10-12 15:29:26 +02:00
coda.rst Documentation: coda: annotate duplicated words 2020-07-13 10:02:32 -06:00
configfs.rst
cramfs.rst
dax.rst docs: convert dax.txt to rst 2021-06-04 11:31:02 -06:00
debugfs.rst debugfs: remove return value of debugfs_create_bool() 2021-05-21 20:59:03 +02:00
devpts.rst
directory-locking.rst
dlmfs.rst ocfs2: replace HTTP links with HTTPS ones 2020-08-07 11:33:22 -07:00
dnotify.rst
ecryptfs.rst
efivarfs.rst
erofs.rst erofs: add multiple device support 2021-10-18 00:13:30 +08:00
ext2.rst docs: fix a cross-ref 2021-06-13 17:02:46 -06:00
ext3.rst
f2fs.rst f2fs-for-5.16-rc1 2021-11-13 11:20:22 -08:00
fiemap.rst
files.rst file: Rename fcheck lookup_fd_rcu 2020-12-10 12:40:07 -06:00
fscrypt.rst fscrypt: allow 256-bit master keys with AES-256-XTS 2021-09-22 11:29:38 -07:00
fsverity.rst fs-verity: support reading signature with ioctl 2021-02-07 14:51:19 -08:00
fuse-io.rst
fuse.rst fuse: update project homepage 2020-09-04 11:32:10 +02:00
gfs2-glocks.rst
gfs2-uevents.rst
gfs2.rst Documentation: Update filesystems/gfs2.rst 2020-12-01 00:25:20 +01:00
hfs.rst
hfsplus.rst
hpfs.rst
idmappings.rst docs: update mapping documentation 2021-12-03 18:58:11 +01:00
index.rst Documentation: remove reference to now removed mandatory-locking doc 2021-10-05 06:02:53 -04:00
inotify.rst
isofs.rst
journalling.rst jbd2: drop jbd2_fc_init documentation 2020-11-06 23:01:03 -05:00
locking.rst doc: fs: remove bdev_try_to_free_page related doc 2021-12-23 12:40:53 -07:00
locks.rst docs: fs: locks.rst: update comment about mandatory file locking 2021-10-19 06:48:21 -04:00
mount_api.rst Documentation: mount_api: change kernel log wording 2020-12-03 15:53:13 -07:00
netfs_library.rst netfs: Adjust docs after foliation 2021-11-29 10:10:26 -08:00
nilfs2.rst
ntfs.rst
ntfs3.rst Doc/fs/ntfs3: Fix rst format and make it cleaner 2021-09-20 18:53:12 +03:00
ocfs2-online-filecheck.rst
ocfs2.rst ocfs2: replace HTTP links with HTTPS ones 2020-08-07 11:33:22 -07:00
omfs.rst Replace HTTP links with HTTPS ones: OMFS 2020-07-13 11:24:43 -06:00
orangefs.rst
overlayfs.rst ovl: skip checking lower file's i_writecount on truncate 2021-08-17 11:47:44 +02:00
path-lookup.rst Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-07-03 11:41:14 -07:00
path-lookup.txt
porting.rst Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-07-03 11:41:14 -07:00
proc.rst docs: proc.rst: mountinfo: align columns 2021-10-12 13:52:22 -06:00
qnx6.rst
quota.rst quota: Fixup http links in quota doc 2020-07-09 08:14:01 +02:00
ramfs-rootfs-initramfs.rst Documentation: Fix intiramfs script name 2021-07-18 23:48:14 +09:00
relay.rst
romfs.rst
seq_file.rst seq_file: document how per-entry resources are managed. 2021-02-26 09:41:05 -08:00
sharedsubtree.rst
splice.rst
squashfs.rst
sysfs.rst Driver Core patches for 5.10-rc1 2020-10-14 16:09:32 -07:00
sysv-fs.rst
tmpfs.rst tmpfs: fix Documentation nits 2020-12-15 12:13:39 -08:00
ubifs-authentication.rst docs: ubifs-authentication: Add a top-level heading 2020-09-09 11:53:33 -06:00
ubifs.rst
udf.rst udf: Replace HTTP links with HTTPS ones 2020-07-14 14:37:39 +02:00
vfat.rst docs: filesystems: Fix a mundane typo 2021-03-25 11:51:23 -06:00
vfs.rst vfs: add rcu argument to ->get_acl() callback 2021-08-18 22:08:24 +02:00
virtiofs.rst
xfs-delayed-logging-design.rst
xfs-self-describing-metadata.rst
zonefs.rst zonefs: document the explicit-open mount option 2020-09-15 18:32:58 +09:00