Merge tag 'v6.6.75' into for/openbmc/dev-6.6

This is the 6.6.75 stable release

libfs: Use d_children list to iterate simple_offset directories

[ Upstream commit b9b588f22a0c049a14885399e27625635ae6ef91 ]

The mtree mechanism has been effective at creating directory offsets
tha

libfs: Use d_children list to iterate simple_offset directories

[ Upstream commit b9b588f22a0c049a14885399e27625635ae6ef91 ]

The mtree mechanism has been effective at creating directory offsets
that are stable over multiple opendir instances. However, it has not
been able to handle the subtleties of renames that are concurrent
with readdir.

Instead of using the mtree to emit entries in the order of their
offset values, use it only to map incoming ctx->pos to a starting
entry. Then use the directory's d_children list, which is already
maintained properly by the dcache, to find the next child to emit.

One of the sneaky things about this is that when the mtree-allocated
offset value wraps (which is very rare), looking up ctx->pos++ is
not going to find the next entry; it will return NULL. Instead, by
following the d_children list, the offset values can appear in any
order but all of the entries in the directory will be visited
eventually.

Note also that the readdir() is guaranteed to reach the tail of this
list. Entries are added only at the head of d_children, and readdir
walks from its current position in that list towards its tail.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20241228175522.1854234-6-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
[ cel: adjusted to apply to origin/linux-6.6.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Replace simple_offset end-of-directory detection

[ Upstream commit 68a3a65003145644efcbb651e91db249ccd96281 ]

According to getdents(3), the d_off field in each returned directory
entry point

libfs: Replace simple_offset end-of-directory detection

[ Upstream commit 68a3a65003145644efcbb651e91db249ccd96281 ]

According to getdents(3), the d_off field in each returned directory
entry points to the next entry in the directory. The d_off field in
the last returned entry in the readdir buffer must contain a valid
offset value, but if it points to an actual directory entry, then
readdir/getdents can loop.

This patch introduces a specific fixed offset value that is placed
in the d_off field of the last entry in a directory. Some user space
applications assume that the EOD offset value is larger than the
offsets of real directory entries, so the largest valid offset value
is reserved for this purpose. This new value is never allocated by
simple_offset_add().

When ->iterate_dir() returns, getdents{64} inserts the ctx->pos
value into the d_off field of the last valid entry in the readdir
buffer. When it hits EOD, offset_readdir() sets ctx->pos to the EOD
offset value so the last entry is updated to point to the EOD marker.

When trying to read the entry at the EOD offset, offset_readdir()
terminates immediately.

It is worth noting that using a Maple tree for directory offset
value allocation does not guarantee a 63-bit range of values --
on platforms where "long" is a 32-bit type, the directory offset
value range is still 0..(2^31 - 1). For broad compatibility with
32-bit user space, the largest tmpfs directory cookie value is now
S32_MAX.

Fixes: 796432efab1e ("libfs: getdents() should return 0 after reaching EOD")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20241228175522.1854234-5-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
[ cel: adjusted to apply to origin/linux-6.6.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Revert "libfs: Add simple_offset_empty()"

[ Upstream commit d7bde4f27ceef3dc6d72010a20d4da23db835a32 ]

simple_empty() and simple_offset_empty() perform the same task.
The latter's use as a canary t

Revert "libfs: Add simple_offset_empty()"

[ Upstream commit d7bde4f27ceef3dc6d72010a20d4da23db835a32 ]

simple_empty() and simple_offset_empty() perform the same task.
The latter's use as a canary to find bugs has not found any new
issues. A subsequent patch will remove the use of the mtree for
iterating directory contents, so revert back to using a similar
mechanism for determining whether a directory is indeed empty.

Only one such mechanism is ever needed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20241228175522.1854234-3-cel@kernel.org
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
[ cel: adjusted to apply to origin/linux-6.6.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Return ENOSPC when the directory offset range is exhausted

[ Upstream commit 903dc9c43a155e0893280c7472d4a9a3a83d75a6 ]

Testing shows that the EBUSY error return from mtree_alloc_cyclic()
le

libfs: Return ENOSPC when the directory offset range is exhausted

[ Upstream commit 903dc9c43a155e0893280c7472d4a9a3a83d75a6 ]

Testing shows that the EBUSY error return from mtree_alloc_cyclic()
leaks into user space. The ERRORS section of "man creat(2)" says:

> EBUSY O_EXCL was specified in flags and pathname refers
> to a block device that is in use by the system
> (e.g., it is mounted).

ENOSPC is closer to what applications expect in this situation.

Note that the normal range of simple directory offset values is
2..2^63, so hitting this error is going to be rare to impossible.

Fixes: 6faddda69f62 ("libfs: Add directory operations for stable offsets")
Cc: stable@vger.kernel.org # v6.9+
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20241228175522.1854234-2-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
[ cel: adjusted to apply to origin/linux-6.6.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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shmem: Fix shmem_rename2()

[ Upstream commit ad191eb6d6942bb835a0b20b647f7c53c1d99ca4 ]

When renaming onto an existing directory entry, user space expects
the replacement entry to have the same dir

shmem: Fix shmem_rename2()

[ Upstream commit ad191eb6d6942bb835a0b20b647f7c53c1d99ca4 ]

When renaming onto an existing directory entry, user space expects
the replacement entry to have the same directory offset as the
original one.

Link: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15966
Fixes: a2e459555c5f ("shmem: stable directory offsets")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-4-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Add simple_offset_rename() API

[ Upstream commit 5a1a25be995e1014abd01600479915683e356f5c ]

I'm about to fix a tmpfs rename bug that requires the use of
internal simple_offset helpers that a

libfs: Add simple_offset_rename() API

[ Upstream commit 5a1a25be995e1014abd01600479915683e356f5c ]

I'm about to fix a tmpfs rename bug that requires the use of
internal simple_offset helpers that are not available in mm/shmem.c

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-3-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Fix simple_offset_rename_exchange()

[ Upstream commit 23cdd0eed3f1fff3af323092b0b88945a7950d8e ]

User space expects the replacement (old) directory entry to have
the same directory offset af

libfs: Fix simple_offset_rename_exchange()

[ Upstream commit 23cdd0eed3f1fff3af323092b0b88945a7950d8e ]

User space expects the replacement (old) directory entry to have
the same directory offset after the rename.

Suggested-by: Christian Brauner <brauner@kernel.org>
Fixes: a2e459555c5f ("shmem: stable directory offsets")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-2-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
[ cel: adjusted to apply to origin/linux-6.6.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Add simple_offset_empty()

[ Upstream commit ecba88a3b32d733d41e27973e25b2bc580f64281 ]

For simple filesystems that use directory offset mapping, rely
strictly on the directory offset map to

libfs: Add simple_offset_empty()

[ Upstream commit ecba88a3b32d733d41e27973e25b2bc580f64281 ]

For simple filesystems that use directory offset mapping, rely
strictly on the directory offset map to tell when a directory has
no children.

After this patch is applied, the emptiness test holds only the RCU
read lock when the directory being tested has no children.

In addition, this adds another layer of confirmation that
simple_offset_add/remove() are working as expected.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/170820143463.6328.7872919188371286951.stgit@91.116.238.104.host.secureserver.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: 5a1a25be995e ("libfs: Add simple_offset_rename() API")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Define a minimum directory offset

[ Upstream commit 7beea725a8ca412c6190090ce7c3a13b169592a1 ]

This value is used in several places, so make it a symbolic
constant.

Reviewed-by: Jan Kara <j

libfs: Define a minimum directory offset

[ Upstream commit 7beea725a8ca412c6190090ce7c3a13b169592a1 ]

This value is used in several places, so make it a symbolic
constant.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/170820142741.6328.12428356024575347885.stgit@91.116.238.104.host.secureserver.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: ecba88a3b32d ("libfs: Add simple_offset_empty()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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libfs: Re-arrange locking in offset_iterate_dir()

[ Upstream commit 3f6d810665dfde0d33785420618ceb03fba0619d ]

Liam and Matthew say that once the RCU read lock is released,
xa_state is not safe to

libfs: Re-arrange locking in offset_iterate_dir()

[ Upstream commit 3f6d810665dfde0d33785420618ceb03fba0619d ]

Liam and Matthew say that once the RCU read lock is released,
xa_state is not safe to re-use for the next xas_find() call. But the
RCU read lock must be released on each loop iteration so that
dput(), which might_sleep(), can be called safely.

Thus we are forced to walk the offset tree with fresh state for each
directory entry. xa_find() can do this for us, though it might be a
little less efficient than maintaining xa_state locally.

We believe that in the current code base, inode->i_rwsem provides
protection for the xa_state maintained in
offset_iterate_dir(). However, there is no guarantee that will
continue to be the case in the future.

Since offset_iterate_dir() doesn't build xa_state locally any more,
there's no longer a strong need for offset_find_next(). Clean up by
rolling these two helpers together.

Suggested-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Message-ID: <170785993027.11135.8830043889278631735.stgit@91.116.238.104.host.secureserver.net>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/170820142021.6328.15047865406275957018.stgit@91.116.238.104.host.secureserver.net
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Merge tag 'v6.6.10' into dev-6.6

This is the 6.6.10 stable release

fs: new accessor methods for atime and mtime

[ Upstream commit 077c212f0344ae4198b2b51af128a94b614ccdf4 ]

Recently, we converted the ctime accesses in the kernel to use new
accessor functions. Linu

fs: new accessor methods for atime and mtime

[ Upstream commit 077c212f0344ae4198b2b51af128a94b614ccdf4 ]

Recently, we converted the ctime accesses in the kernel to use new
accessor functions. Linus recently pointed out though that if we add
accessors for the atime and mtime, then that would allow us to
seamlessly change how these timestamps are stored in the inode.

Add new accessor functions for the atime and mtime that mirror the
accessors for the ctime.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20231004185239.80830-1-jlayton@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: 01fe654f78fd ("fs: cifs: Fix atime update check")
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Merge tag 'v6.6.6' into dev-6.6

This is the 6.6.6 stable release

Signed-off-by: Joel Stanley <joel@jms.id.au>

libfs: getdents() should return 0 after reaching EOD

[ Upstream commit 796432efab1e372d404e7a71cc6891a53f105051 ]

The new directory offset helpers don't conform with the convention
of getdents() re

libfs: getdents() should return 0 after reaching EOD

[ Upstream commit 796432efab1e372d404e7a71cc6891a53f105051 ]

The new directory offset helpers don't conform with the convention
of getdents() returning no more entries once a directory file
descriptor has reached the current end-of-directory.

To address this, copy the logic from dcache_readdir() to mark the
open directory file descriptor once EOD has been reached. Seeking
resets the mark.

Reported-by: Tavian Barnes <tavianator@tavianator.com>
Closes: https://lore.kernel.org/linux-fsdevel/20231113180616.2831430-1-tavianator@tavianator.com/
Fixes: 6faddda69f62 ("libfs: Add directory operations for stable offsets")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/170043792492.4628.15646203084646716134.stgit@bazille.1015granger.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Merge tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
"This contains the usual miscellaneous fixes and cleanups for vfs and

Merge tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
"This contains the usual miscellaneous fixes and cleanups for vfs and
individual fses:

Fixes:
- Revert ki_pos on error from buffered writes for direct io fallback
- Add missing documentation for block device and superblock handling
for changes merged this cycle
- Fix reiserfs flexible array usage
- Ensure that overlayfs sets ctime when setting mtime and atime
- Disable deferred caller completions with overlayfs writes until
proper support exists

Cleanups:
- Remove duplicate initialization in pipe code
- Annotate aio kioctx_table with __counted_by"

* tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
overlayfs: set ctime when setting mtime and atime
ntfs3: put resources during ntfs_fill_super()
ovl: disable IOCB_DIO_CALLER_COMP
porting: document superblock as block device holder
porting: document new block device opening order
fs/pipe: remove duplicate "offset" initializer
fs-writeback: do not requeue a clean inode having skipped pages
aio: Annotate struct kioctx_table with __counted_by
direct_write_fallback(): on error revert the ->ki_pos update from buffered write
reiserfs: Replace 1-element array with C99 style flex-array

show more ...

direct_write_fallback(): on error revert the ->ki_pos update from buffered write

If we fail filemap_write_and_wait_range() on the range the buffered write went
into, we only report the "number of by

direct_write_fallback(): on error revert the ->ki_pos update from buffered write

If we fail filemap_write_and_wait_range() on the range the buffered write went
into, we only report the "number of bytes which we direct-written", to quote
the comment in there. Which is fine, but buffered write has already advanced
iocb->ki_pos, so we need to roll that back. Otherwise we end up with e.g.
write(2) advancing position by more than the amount it reports having written.

Fixes: 182c25e9c157 "filemap: update ki_pos in generic_perform_write"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Message-Id: <20230827214518.GU3390869@ZenIV>
Signed-off-by: Christian Brauner <brauner@kernel.org>

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Merge drm/drm-fixes into drm-misc-fixes

Forwarding to v6.6-rc1.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge tag 'ext4_for_linus-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:
"Many ext4 and jbd2 cleanups and bug fixes:

- Cleanups in the ext

Merge tag 'ext4_for_linus-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:
"Many ext4 and jbd2 cleanups and bug fixes:

- Cleanups in the ext4 remount code when going to and from read-only

- Cleanups in ext4's multiblock allocator

- Cleanups in the jbd2 setup/mounting code paths

- Performance improvements when appending to a delayed allocation file

- Miscellaneous syzbot and other bug fixes"

* tag 'ext4_for_linus-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (60 commits)
ext4: fix slab-use-after-free in ext4_es_insert_extent()
libfs: remove redundant checks of s_encoding
ext4: remove redundant checks of s_encoding
ext4: reject casefold inode flag without casefold feature
ext4: use LIST_HEAD() to initialize the list_head in mballoc.c
ext4: do not mark inode dirty every time when appending using delalloc
ext4: rename s_error_work to s_sb_upd_work
ext4: add periodic superblock update check
ext4: drop dio overwrite only flag and associated warning
ext4: add correct group descriptors and reserved GDT blocks to system zone
ext4: remove unused function declaration
ext4: mballoc: avoid garbage value from err
ext4: use sbi instead of EXT4_SB(sb) in ext4_mb_new_blocks_simple()
ext4: change the type of blocksize in ext4_mb_init_cache()
ext4: fix unttached inode after power cut with orphan file feature enabled
jbd2: correct the end of the journal recovery scan range
ext4: ext4_get_{dev}_journal return proper error value
ext4: cleanup ext4_get_dev_journal() and ext4_get_journal()
jbd2: jbd2_journal_init_{dev,inode} return proper error return value
jbd2: drop useless error tag in jbd2_journal_wipe()
...

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Merge branch 'next' into for-linus

Prepare input updates for 6.6 merge window.

Merge tag 'v6.6-vfs.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes

Merge tag 'v6.6-vfs.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual filesystems.

Features:

- Block mode changes on symlinks and rectify our broken semantics

- Report file modifications via fsnotify() for splice

- Allow specifying an explicit timeout for the "rootwait" kernel
command line option. This allows to timeout and reboot instead of
always waiting indefinitely for the root device to show up

- Use synchronous fput for the close system call

Cleanups:

- Get rid of open-coded lockdep workarounds for async io submitters
and replace it all with a single consolidated helper

- Simplify epoll allocation helper

- Convert simple_write_begin and simple_write_end to use a folio

- Convert page_cache_pipe_buf_confirm() to use a folio

- Simplify __range_close to avoid pointless locking

- Disable per-cpu buffer head cache for isolated cpus

- Port ecryptfs to kmap_local_page() api

- Remove redundant initialization of pointer buf in pipe code

- Unexport the d_genocide() function which is only used within core
vfs

- Replace printk(KERN_ERR) and WARN_ON() with WARN()

Fixes:

- Fix various kernel-doc issues

- Fix refcount underflow for eventfds when used as EFD_SEMAPHORE

- Fix a mainly theoretical issue in devpts

- Check the return value of __getblk() in reiserfs

- Fix a racy assert in i_readcount_dec

- Fix integer conversion issues in various functions

- Fix LSM security context handling during automounts that prevented
NFS superblock sharing"

* tag 'v6.6-vfs.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (39 commits)
cachefiles: use kiocb_{start,end}_write() helpers
ovl: use kiocb_{start,end}_write() helpers
aio: use kiocb_{start,end}_write() helpers
io_uring: use kiocb_{start,end}_write() helpers
fs: create kiocb_{start,end}_write() helpers
fs: add kerneldoc to file_{start,end}_write() helpers
io_uring: rename kiocb_end_write() local helper
splice: Convert page_cache_pipe_buf_confirm() to use a folio
libfs: Convert simple_write_begin and simple_write_end to use a folio
fs/dcache: Replace printk and WARN_ON by WARN
fs/pipe: remove redundant initialization of pointer buf
fs: Fix kernel-doc warnings
devpts: Fix kernel-doc warnings
doc: idmappings: fix an error and rephrase a paragraph
init: Add support for rootwait timeout parameter
vfs: fix up the assert in i_readcount_dec
fs: Fix one kernel-doc comment
docs: filesystems: idmappings: clarify from where idmappings are taken
fs/buffer.c: disable per-CPU buffer_head cache for isolated CPUs
vfs, security: Fix automount superblock LSM init problem, preventing NFS sb sharing
...

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Merge tag 'v6.6-vfs.tmpfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull libfs and tmpfs updates from Christian Brauner:
"This cycle saw a lot of work for tmpfs that required change

Merge tag 'v6.6-vfs.tmpfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull libfs and tmpfs updates from Christian Brauner:
"This cycle saw a lot of work for tmpfs that required changes to the
vfs layer. Andrew, Hugh, and I decided to take tmpfs through vfs this
cycle. Things will go back to mm next cycle.

Features
========

- By far the biggest work is the quota support for tmpfs. New tmpfs
quota infrastructure is added to support it and a new QFMT_SHMEM
uapi option is exposed.

This offers user and group quotas to tmpfs (project quotas will be
added later). Similar to other filesystems tmpfs quota are not
supported within user namespaces yet.

- Add support for user xattrs. While tmpfs already supports security
xattrs (security.*) and POSIX ACLs for a long time it lacked
support for user xattrs (user.*). With this pull request tmpfs will
be able to support a limited number of user xattrs.

This is accompanied by a fix (see below) to limit persistent simple
xattr allocations.

- Add support for stable directory offsets. Currently tmpfs relies on
the libfs provided cursor-based mechanism for readdir. This causes
issues when a tmpfs filesystem is exported via NFS.

NFS clients do not open directories. Instead, each server-side
readdir operation opens the directory, reads it, and then closes
it. Since the cursor state for that directory is associated with
the opened file it is discarded after each readdir operation. Such
directory offsets are not just cached by NFS clients but also
various userspace libraries based on these clients.

As it stands there is no way to invalidate the caches when
directory offsets have changed and the whole application depends on
unchanging directory offsets.

At LSFMM we discussed how to solve this problem and decided to
support stable directory offsets. libfs now allows filesystems like
tmpfs to use an xarrary to map a directory offset to a dentry. This
mechanism is currently only used by tmpfs but can be supported by
others as well.

Fixes
=====

- Change persistent simple xattrs allocations in libfs from
GFP_KERNEL to GPF_KERNEL_ACCOUNT so they're subject to memory
cgroup limits. Since this is a change to libfs it affects both
tmpfs and kernfs.

- Correctly verify {g,u}id mount options.

A new filesystem context is created via fsopen() which records the
namespace that becomes the owning namespace of the superblock when
fsconfig(FSCONFIG_CMD_CREATE) is called for filesystems that are
mountable in namespaces. However, fsconfig() calls can occur in a
namespace different from the namespace where fsopen() has been
called.

Currently, when fsconfig() is called to set {g,u}id mount options
the requested {g,u}id is mapped into a k{g,u}id according to the
namespace where fsconfig() was called from. The resulting k{g,u}id
is not guaranteed to be resolvable in the namespace of the
filesystem (the one that fsopen() was called in).

This means it's possible for an unprivileged user to create files
owned by any group in a tmpfs mount since it's possible to set the
setid bits on the tmpfs directory.

The contract for {g,u}id mount options and {g,u}id values in
general set from userspace has always been that they are translated
according to the caller's idmapping. In so far, tmpfs has been
doing the correct thing. But since tmpfs is mountable in
unprivileged contexts it is also necessary to verify that the
resulting {k,g}uid is representable in the namespace of the
superblock to avoid such bugs.

The new mount api's cross-namespace delegation abilities are
already widely used. Having talked to a bunch of userspace this is
the most faithful solution with minimal regression risks"

* tag 'v6.6-vfs.tmpfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
tmpfs,xattr: GFP_KERNEL_ACCOUNT for simple xattrs
mm: invalidation check mapping before folio_contains
tmpfs: trivial support for direct IO
tmpfs,xattr: enable limited user extended attributes
tmpfs: track free_ispace instead of free_inodes
xattr: simple_xattr_set() return old_xattr to be freed
tmpfs: verify {g,u}id mount options correctly
shmem: move spinlock into shmem_recalc_inode() to fix quota support
libfs: Remove parent dentry locking in offset_iterate_dir()
libfs: Add a lock class for the offset map's xa_lock
shmem: stable directory offsets
shmem: Refactor shmem_symlink()
libfs: Add directory operations for stable offsets
shmem: fix quota lock nesting in huge hole handling
shmem: Add default quota limit mount options
shmem: quota support
shmem: prepare shmem quota infrastructure
quota: Check presence of quota operation structures instead of ->quota_read and ->quota_write callbacks
shmem: make shmem_get_inode() return ERR_PTR instead of NULL
shmem: make shmem_inode_acct_block() return error

show more ...

Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs timestamp updates from Christian Brauner:
"This adds VFS support for multi-grain timestamps and converts

Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs timestamp updates from Christian Brauner:
"This adds VFS support for multi-grain timestamps and converts tmpfs,
xfs, ext4, and btrfs to use them. This carries acks from all relevant
filesystems.

The VFS always uses coarse-grained timestamps when updating the ctime
and mtime after a change. This has the benefit of allowing filesystems
to optimize away a lot of metadata updates, down to around 1 per
jiffy, even when a file is under heavy writes.

Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide to invalidate the cache.

Even with NFSv4, a lot of exported filesystems don't properly support
a change attribute and are subject to the same problems with timestamp
granularity. Other applications have similar issues with timestamps
(e.g., backup applications).

If we were to always use fine-grained timestamps, that would improve
the situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.

This introduces fine-grained timestamps that are used when they are
actively queried.

This uses the 31st bit of the ctime tv_nsec field to indicate that
something has queried the inode for the mtime or ctime. When this flag
is set, on the next mtime or ctime update, the kernel will fetch a
fine-grained timestamp instead of the usual coarse-grained one.

As POSIX generally mandates that when the mtime changes, the ctime
must also change the kernel always stores normalized ctime values, so
only the first 30 bits of the tv_nsec field are ever used.

Filesytems can opt into this behavior by setting the FS_MGTIME flag in
the fstype. Filesystems that don't set this flag will continue to use
coarse-grained timestamps.

Various preparatory changes, fixes and cleanups are included:

- Fixup all relevant places where POSIX requires updating ctime
together with mtime. This is a wide-range of places and all
maintainers provided necessary Acks.

- Add new accessors for inode->i_ctime directly and change all
callers to rely on them. Plain accesses to inode->i_ctime are now
gone and it is accordingly rename to inode->__i_ctime and commented
as requiring accessors.

- Extend generic_fillattr() to pass in a request mask mirroring in a
sense the statx() uapi. This allows callers to pass in a request
mask to only get a subset of attributes filled in.

- Rework timestamp updates so it's possible to drop the @now
parameter the update_time() inode operation and associated helpers.

- Add inode_update_timestamps() and convert all filesystems to it
removing a bunch of open-coding"

* tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits)
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
tmpfs: add support for multigrain timestamps
fs: add infrastructure for multigrain timestamps
fs: drop the timespec64 argument from update_time
xfs: have xfs_vn_update_time gets its own timestamp
fat: make fat_update_time get its own timestamp
fat: remove i_version handling from fat_update_time
ubifs: have ubifs_update_time use inode_update_timestamps
btrfs: have it use inode_update_timestamps
fs: drop the timespec64 arg from generic_update_time
fs: pass the request_mask to generic_fillattr
fs: remove silly warning from current_time
gfs2: fix timestamp handling on quota inodes
fs: rename i_ctime field to __i_ctime
selinux: convert to ctime accessor functions
security: convert to ctime accessor functions
apparmor: convert to ctime accessor functions
sunrpc: convert to ctime accessor functions
...

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libfs: remove redundant checks of s_encoding

Now that neither ext4 nor f2fs allows inodes with the casefold flag to
be instantiated when unsupported, it's unnecessary to repeatedly check
for support

libfs: remove redundant checks of s_encoding

Now that neither ext4 nor f2fs allows inodes with the casefold flag to
be instantiated when unsupported, it's unnecessary to repeatedly check
for support later on during random filesystem operations.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230814182903.37267-4-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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libfs: Convert simple_write_begin and simple_write_end to use a folio

Remove a number of implicit calls to compound_head() and various calls
to compatibility functions. This is not sufficient to en

libfs: Convert simple_write_begin and simple_write_end to use a folio

Remove a number of implicit calls to compound_head() and various calls
to compatibility functions. This is not sufficient to enable support
for large folios; generic_perform_write() must be converted first.

Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Message-Id: <20230821141322.2535459-1-willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

show more ...