linux.git/fs/fcntl.c, branch v6.9

Merge tag 'vfs-6.9.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-03-11T17:07:03+00:00

Pull iomap updates from Christian Brauner:

 - Restore read-write hints in struct bio through the bi_write_hint
   member for the sake of UFS devices in mobile applications. This can
   result in up to 40% lower write amplification in UFS devices. The
   patch series that builds on this will be coming in via the SCSI
   maintainers (Bart)

 - Overhaul the iomap writeback code. Afterwards ->map_blocks() is able
   to map multiple blocks at once as long as they're in the same folio.
   This reduces CPU usage for buffered write workloads on e.g., xfs on
   systems with lots of cores (Christoph)

 - Record processed bytes in iomap_iter() trace event (Kassey)

 - Extend iomap_writepage_map() trace event after Christoph's
   ->map_block() changes to map mutliple blocks at once (Zhang)

* tag 'vfs-6.9.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
  iomap: Add processed for iomap_iter
  iomap: add pos and dirty_len into trace_iomap_writepage_map
  block, fs: Restore the per-bio/request data lifetime fields
  fs: Propagate write hints to the struct block_device inode
  fs: Move enum rw_hint into a new header file
  fs: Split fcntl_rw_hint()
  fs: Verify write lifetime constants at compile time
  fs: Fix rw_hint validation
  iomap: pass the length of the dirty region to ->map_blocks
  iomap: map multiple blocks at a time
  iomap: submit ioends immediately
  iomap: factor out a iomap_writepage_map_block helper
  iomap: only call mapping_set_error once for each failed bio
  iomap: don't chain bios
  iomap: move the iomap_sector sector calculation out of iomap_add_to_ioend
  iomap: clean up the iomap_alloc_ioend calling convention
  iomap: move all remaining per-folio logic into iomap_writepage_map
  iomap: factor out a iomap_writepage_handle_eof helper
  iomap: move the PF_MEMALLOC check to iomap_writepages
  iomap: move the io_folios field out of struct iomap_ioend
  ...

fs: prefer kfree_rcu() in fasync_remove_entry()

2024-02-12T10:00:10+00:00

In 'fasync_remove_entry()', prefer 'kfree_rcu()' over 'call_rcu()' with dummy
'fasync_free_rcu()' callback. This is mostly intended in attempt to fix weird
https://syzkaller.appspot.com/bug?id=6a64ad907e361e49e92d1c4c114128a1bda2ed7f,
where kmemleak may consider 'fa' as unreferenced during RCU grace period. See
https://lore.kernel.org/stable/20230930174657.800551-1-joel@joelfernandes.org
as well. Comments are highly appreciated.

Ever since ae65a5211d90 ("mm/slab: document kfree() as allowed for
kmem_cache_alloc() objects") kfree() can be used for both kmalloc() and
kmem_cache_alloc() so this is no safe.

Do not backport this to stable, please.

Link ae65a5211d90 ("mm/slab: document kfree() as > allowed for kmem_cache_alloc() objects")
Signed-off-by: Dmitry Antipov 
Link: https://lore.kernel.org/r/20240209125220.330383-1-dmantipov@yandex.ru
Signed-off-by: Christian Brauner

fs: Propagate write hints to the struct block_device inode

2024-02-06T13:30:48+00:00

Write hints applied with F_SET_RW_HINT on a block device affect the
block device inode only. Propagate these hints to the inode associated
with struct block_device because that is the inode used when writing
back dirty pages.

Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Jens Axboe 
Cc: Christoph Hellwig 
Cc: Jeff Layton 
Cc: Chuck Lever 
Cc: Kanchan Joshi 
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20240202203926.2478590-6-bvanassche@acm.org
Signed-off-by: Christian Brauner

fs: Move enum rw_hint into a new header file

2024-02-06T13:30:48+00:00

Move enum rw_hint into a new header file to prepare for using this data
type in the block layer. Add the attribute __packed to reduce the space
occupied by instances of this data type from four bytes to one byte.
Change the data type of i_write_hint from u8 into enum rw_hint.

Reviewed-by: Christoph Hellwig 
Acked-by: Chao Yu  # for the F2FS part
Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Jan Kara 
Cc: Christoph Hellwig 
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20240202203926.2478590-5-bvanassche@acm.org
Signed-off-by: Christian Brauner

fs: Split fcntl_rw_hint()

2024-02-06T13:30:47+00:00

Split fcntl_rw_hint() such that there is one helper function per fcntl.
Use READ_ONCE() and WRITE_ONCE() to access the i_write_hint member
instead of protecting such accesses with the inode lock. READ_ONCE() is
not used in I/O path code that reads i_write_hint. Users who want
F_SET_RW_HINT to affect I/O need to make sure that F_SET_RW_HINT has
completed before I/O is submitted that should use the configured write
hint.

Cc: Christoph Hellwig 
Suggested-by: Christoph Hellwig 
Cc: Kanchan Joshi 
Cc: Jeff Layton 
Cc: Chuck Lever 
Cc: Jens Axboe 
Cc: Stephen Rothwell 
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20240202203926.2478590-4-bvanassche@acm.org
Signed-off-by: Christian Brauner

fs: Verify write lifetime constants at compile time

2024-02-06T13:30:47+00:00

The code in fs/fcntl.c converts RWH_* constants to and from WRITE_LIFE_*
constants using casts. Verify at compile time that these casts will yield
the intended effect.

Reviewed-by: Christoph Hellwig 
Suggested-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20240202203926.2478590-3-bvanassche@acm.org
Signed-off-by: Christian Brauner

fs: Fix rw_hint validation

2024-02-06T13:30:47+00:00

Reject values that are valid rw_hints after truncation but not before
truncation by passing an untruncated value to rw_hint_valid().

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kanchan Joshi 
Cc: Jeff Layton 
Cc: Chuck Lever 
Cc: Jens Axboe 
Cc: Stephen Rothwell 
Fixes: 5657cb0797c4 ("fs/fcntl: use copy_to/from_user() for u64 types")
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20240202203926.2478590-2-bvanassche@acm.org
Signed-off-by: Christian Brauner

treewide: mark stuff as __ro_after_init

2023-10-18T21:43:23+00:00

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton

fcntl: Cast commands with int args explicitly

2023-07-10T12:36:11+00:00

According to the fcntl API specification commands that expect an
integer, hence not a pointer, always take an int and not long. In
order to avoid access to undefined bits, we should explicitly cast
the argument to int.

Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Jeff Layton 
Cc: Chuck Lever 
Cc: Kevin Brodsky 
Cc: Vincenzo Frascino 
Cc: Szabolcs Nagy 
Cc: "Theodore Ts'o" 
Cc: David Laight 
Cc: Mark Rutland 
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-morello@op-lists.linaro.org
Signed-off-by: Luca Vizzarro 
Message-Id: <20230414152459.816046-2-Luca.Vizzarro@arm.com>
Signed-off-by: Christian Brauner

Merge tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

2023-02-20T19:53:11+00:00

Pull vfs idmapping updates from Christian Brauner:

 - Last cycle we introduced the dedicated struct mnt_idmap type for
   mount idmapping and the required infrastucture in 256c8aed2b42 ("fs:
   introduce dedicated idmap type for mounts"). As promised in last
   cycle's pull request message this converts everything to rely on
   struct mnt_idmap.

   Currently we still pass around the plain namespace that was attached
   to a mount. This is in general pretty convenient but it makes it easy
   to conflate namespaces that are relevant on the filesystem with
   namespaces that are relevant on the mount level. Especially for
   non-vfs developers without detailed knowledge in this area this was a
   potential source for bugs.

   This finishes the conversion. Instead of passing the plain namespace
   around this updates all places that currently take a pointer to a
   mnt_userns with a pointer to struct mnt_idmap.

   Now that the conversion is done all helpers down to the really
   low-level helpers only accept a struct mnt_idmap argument instead of
   two namespace arguments.

   Conflating mount and other idmappings will now cause the compiler to
   complain loudly thus eliminating the possibility of any bugs. This
   makes it impossible for filesystem developers to mix up mount and
   filesystem idmappings as they are two distinct types and require
   distinct helpers that cannot be used interchangeably.

   Everything associated with struct mnt_idmap is moved into a single
   separate file. With that change no code can poke around in struct
   mnt_idmap. It can only be interacted with through dedicated helpers.
   That means all filesystems are and all of the vfs is completely
   oblivious to the actual implementation of idmappings.

   We are now also able to extend struct mnt_idmap as we see fit. For
   example, we can decouple it completely from namespaces for users that
   don't require or don't want to use them at all. We can also extend
   the concept of idmappings so we can cover filesystem specific
   requirements.

   In combination with the vfs{g,u}id_t work we finished in v6.2 this
   makes this feature substantially more robust and thus difficult to
   implement wrong by a given filesystem and also protects the vfs.

 - Enable idmapped mounts for tmpfs and fulfill a longstanding request.

   A long-standing request from users had been to make it possible to
   create idmapped mounts for tmpfs. For example, to share the host's
   tmpfs mount between multiple sandboxes. This is a prerequisite for
   some advanced Kubernetes cases. Systemd also has a range of use-cases
   to increase service isolation. And there are more users of this.

   However, with all of the other work going on this was way down on the
   priority list but luckily someone other than ourselves picked this
   up.

   As usual the patch is tiny as all the infrastructure work had been
   done multiple kernel releases ago. In addition to all the tests that
   we already have I requested that Rodrigo add a dedicated tmpfs
   testsuite for idmapped mounts to xfstests. It is to be included into
   xfstests during the v6.3 development cycle. This should add a slew of
   additional tests.

* tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping: (26 commits)
  shmem: support idmapped mounts for tmpfs
  fs: move mnt_idmap
  fs: port vfs{g,u}id helpers to mnt_idmap
  fs: port fs{g,u}id helpers to mnt_idmap
  fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap
  fs: port i_{g,u}id_{needs_}update() to mnt_idmap
  quota: port to mnt_idmap
  fs: port privilege checking helpers to mnt_idmap
  fs: port inode_owner_or_capable() to mnt_idmap
  fs: port inode_init_owner() to mnt_idmap
  fs: port acl to mnt_idmap
  fs: port xattr to mnt_idmap
  fs: port ->permission() to pass mnt_idmap
  fs: port ->fileattr_set() to pass mnt_idmap
  fs: port ->set_acl() to pass mnt_idmap
  fs: port ->get_acl() to pass mnt_idmap
  fs: port ->tmpfile() to pass mnt_idmap
  fs: port ->rename() to pass mnt_idmap
  fs: port ->mknod() to pass mnt_idmap
  fs: port ->mkdir() to pass mnt_idmap
  ...