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>

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()
  ...

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
  ...

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

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>

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>

Since offset_iterate_dir() does not walk the parent's d_subdir list
nor does it manipulate the parent's d_child, there doesn't seem to
be a reason to hold the parent's d_lock. The offset_ctx's xarray can
be sufficiently protected with just the RCU read lock.

Flame graph data captured during the git regression run shows a
20% reduction in CPU cycles consumed in offset_find_next().

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202307171640.e299f8d5-oliver.sang@intel.com
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Message-Id: <169030957098.157536.9938425508695693348.stgit@manet.1015granger.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Tie the dynamically-allocated xarray locks into a single class so
contention on the directory offset xarrays can be observed.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Message-Id: <169020933088.160441.9405180953116076087.stgit@manet.1015granger.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Create a vector of directory operations in fs/libfs.c that handles
directory seeks and readdir via stable offsets instead of the
current cursor-based mechanism.

For the moment these are unused.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Message-Id: <168814732984.530310.11190772066786107220.stgit@manet.1015granger.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>

generic_fillattr just fills in the entire stat struct indiscriminately
today, copying data from the inode. There is at least one attribute
(STATX_CHANGE_COOKIE) that can have side effects when it is reported,
and we're looking at adding more with the addition of multigrain
timestamps.

Add a request_mask argument to generic_fillattr and have most callers
just pass in the value that is passed to getattr. Have other callers
(e.g. ksmbd) just pass in STATX_BASIC_STATS. Also move the setting of
STATX_CHANGE_COOKIE into generic_fillattr.

Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: "Paulo Alcantara (SUSE)" <pc@manguebit.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230807-mgctime-v7-2-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>