linux-stable.git/fs/cachefiles, branch linux-6.15.y

cachefiles: Fix the incorrect return value in __cachefiles_write()

2025-07-24T06:58:34+00:00

[ Upstream commit 6b89819b06d8d339da414f06ef3242f79508be5e ]

In __cachefiles_write(), if the return value of the write operation > 0, it
is set to 0. This makes it impossible to distinguish scenarios where a
partial write has occurred, and will affect the outer calling functions:

 1) cachefiles_write_complete() will call "term_func" such as
netfs_write_subrequest_terminated(). When "ret" in __cachefiles_write()
is used as the "transferred_or_error" of this function, it can not
distinguish the amount of data written, makes the WARN meaningless.

 2) cachefiles_ondemand_fd_write_iter() can only assume all writes were
successful by default when "ret" is 0, and unconditionally return the full
length specified by user space.

Fix it by modifying "ret" to reflect the actual number of bytes written.
Furthermore, returning a value greater than 0 from __cachefiles_write()
does not affect other call paths, such as cachefiles_issue_write() and
fscache_write().

Fixes: 047487c947e8 ("cachefiles: Implement the I/O routines")
Signed-off-by: Zizhi Wo 
Link: https://lore.kernel.org/20250703024418.2809353-1-wozizhi@huaweicloud.com
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

netfs: Fix the request's work item to not require a ref

2025-06-19T13:40:21+00:00

[ Upstream commit 20d72b00ca814d748f5663484e5c53bb2bf37a3a ]

When the netfs_io_request struct's work item is queued, it must be supplied
with a ref to the work item struct to prevent it being deallocated whilst
on the queue or whilst it is being processed.  This is tricky to manage as
we have to get a ref before we try and queue it and then we may find it's
already queued and is thus already holding a ref - in which case we have to
try and get rid of the ref again.

The problem comes if we're in BH or IRQ context and need to drop the ref:
if netfs_put_request() reduces the count to 0, we have to do the cleanup -
but the cleanup may need to wait.

Fix this by adding a new work item to the request, ->cleanup_work, and
dispatching that when the refcount hits zero.  That can then synchronously
cancel any outstanding work on the main work item before doing the cleanup.

Adding a new work item also deals with another problem upstream where it's
sometimes changing the work func in the put function and requeuing it -
which has occasionally in the past caused the cleanup to happen
incorrectly.

As a bonus, this allows us to get rid of the 'was_async' parameter from a
bunch of functions.  This indicated whether the put function might not be
permitted to sleep.

Fixes: 3d3c95046742 ("netfs: Provide readahead and readpage netfs helpers")
Signed-off-by: David Howells 
Link: https://lore.kernel.org/20250519090707.2848510-4-dhowells@redhat.com
cc: Paulo Alcantara 
cc: Marc Dionne 
cc: Steve French 
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

gcc-15: add '__nonstring' markers to byte arrays

2025-04-20T18:57:54+00:00

All of these cases are perfectly valid and good traditional C, but hit
by the "you're not NUL-terminating your byte array" warning.

And none of the cases want any terminating NUL character.

Mark them __nonstring to shut up gcc-15 (and in the case of the ak8974
magnetometer driver, I just removed the explicit array size and let gcc
expand the 3-byte and 6-byte arrays by one extra byte, because it was
the simpler change).

Signed-off-by: Linus Torvalds

cachefiles: Fix oops in vfs_mkdir from cachefiles_get_directory

2025-03-25T13:59:14+00:00

Commit c54b386969a5 ("VFS: Change vfs_mkdir() to return the dentry.")
changed cachefiles_get_directory, replacing "subdir" with a ERR_PTR
from the result of cachefiles_inject_write_error, which is either 0
or some error code.  This causes an oops when the resulting pointer
is passed to vfs_mkdir.

Use a similar pattern to what is used earlier in the function; replace
subdir with either the return value from vfs_mkdir, or the ERR_PTR
of the cachefiles_inject_write_error() return value, but only if it
is non zero.

Fixes: c54b386969a5 ("VFS: Change vfs_mkdir() to return the dentry.")
cc: netfs@lists.linux.dev
Signed-off-by: Marc Dionne 
Link: https://lore.kernel.org/r/20250325125905.395372-1-marc.dionne@auristor.com
Signed-off-by: Christian Brauner

Merge tag 'vfs-6.15-rc1.async.dir' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-03-24T17:47:14+00:00

Pull vfs async dir updates from Christian Brauner:
 "This contains cleanups that fell out of the work from async directory
  handling:

   - Change kern_path_locked() and user_path_locked_at() to never return
     a negative dentry. This simplifies the usability of these helpers
     in various places

   - Drop d_exact_alias() from the remaining place in NFS where it is
     still used. This also allows us to drop the d_exact_alias() helper
     completely

   - Drop an unnecessary call to fh_update() from nfsd_create_locked()

   - Change i_op->mkdir() to return a struct dentry

     Change vfs_mkdir() to return a dentry provided by the filesystems
     which is hashed and positive. This allows us to reduce the number
     of cases where the resulting dentry is not positive to very few
     cases. The code in these places becomes simpler and easier to
     understand.

   - Repack DENTRY_* and LOOKUP_* flags"

* tag 'vfs-6.15-rc1.async.dir' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  doc: fix inline emphasis warning
  VFS: Change vfs_mkdir() to return the dentry.
  nfs: change mkdir inode_operation to return alternate dentry if needed.
  fuse: return correct dentry for ->mkdir
  ceph: return the correct dentry on mkdir
  hostfs: store inode in dentry after mkdir if possible.
  Change inode_operations.mkdir to return struct dentry *
  nfsd: drop fh_update() from S_IFDIR branch of nfsd_create_locked()
  nfs/vfs: discard d_exact_alias()
  VFS: add common error checks to lookup_one_qstr_excl()
  VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry
  VFS: repack LOOKUP_ bit flags.
  VFS: repack DENTRY_ flags.

VFS: Change vfs_mkdir() to return the dentry.

2025-03-05T10:52:50+00:00

vfs_mkdir() does not guarantee to leave the child dentry hashed or make
it positive on success, and in many such cases the filesystem had to use
a different dentry which it can now return.

This patch changes vfs_mkdir() to return the dentry provided by the
filesystems which is hashed and positive when provided.  This reduces
the number of cases where the resulting dentry is not positive to a
handful which don't deserve extra efforts.

The only callers of vfs_mkdir() which are interested in the resulting
inode are in-kernel filesystem clients: cachefiles, nfsd, smb/server.
The only filesystems that don't reliably provide the inode are:
- kernfs, tracefs which these clients are unlikely to be interested in
- cifs in some configurations would need to do a lookup to find the
  created inode, but doesn't.  cifs cannot be exported via NFS, is
  unlikely to be used by cachefiles, and smb/server only has a soft
  requirement for the inode, so this is unlikely to be a problem in
  practice.
- hostfs, nfs, cifs may need to do a lookup (rarely for NFS) and it is
  possible for a race to make that lookup fail.  Actual failure
  is unlikely and providing callers handle negative dentries graceful
  they will fail-safe.

So this patch removes the lookup code in nfsd and smb/server and adjusts
them to fail safe if a negative dentry is provided:
- cache-files already fails safe by restarting the task from the
  top - it still does with this change, though it no longer calls
  cachefiles_put_directory() as that will crash if the dentry is
  negative.
- nfsd reports "Server-fault" which it what it used to do if the lookup
  failed. This will never happen on any file-systems that it can actually
  export, so this is of no consequence.  I removed the fh_update()
  call as that is not needed and out-of-place.  A subsequent
  nfsd_create_setattr() call will call fh_update() when needed.
- smb/server only wants the inode to call ksmbd_smb_inherit_owner()
  which updates ->i_uid (without calling notify_change() or similar)
  which can be safely skipping on cifs (I hope).

If a different dentry is returned, the first one is put.  If necessary
the fact that it is new can be determined by comparing pointers.  A new
dentry will certainly have a new pointer (as the old is put after the
new is obtained).
Similarly if an error is returned (via ERR_PTR()) the original dentry is
put.

Reviewed-by: Jeff Layton 
Signed-off-by: NeilBrown 
Link: https://lore.kernel.org/r/20250227013949.536172-7-neilb@suse.de
Signed-off-by: Christian Brauner

make use of anon_inode_getfile_fmode()

2025-02-21T09:25:31+00:00

["fallen through the cracks" misc stuff]

A bunch of anon_inode_getfile() callers follow it with adjusting
->f_mode; we have a helper doing that now, so let's make use
of it.

Signed-off-by: Al Viro 
Link: https://lore.kernel.org/r/20250118014434.GT1977892@ZenIV
Reviewed-by: Jan Kara 
Signed-off-by: Christian Brauner

treewide: const qualify ctl_tables where applicable

2025-01-28T12:48:37+00:00

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.

Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.

Created this by running an spatch followed by a sed command:
Spatch:
    virtual patch

    @
    depends on !(file in "net")
    disable optional_qualifier
    @

    identifier table_name != {
      watchdog_hardlockup_sysctl,
      iwcm_ctl_table,
      ucma_ctl_table,
      memory_allocation_profiling_sysctls,
      loadpin_sysctl_table
    };
    @@

    + const
    struct ctl_table table_name [] = { ... };

sed:
    sed --in-place \
      -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
      kernel/utsname_sysctl.c

Reviewed-by: Song Liu 
Acked-by: Steven Rostedt (Google)  # for kernel/trace/
Reviewed-by: Martin K. Petersen  # SCSI
Reviewed-by: Darrick J. Wong  # xfs
Acked-by: Jani Nikula 
Acked-by: Corey Minyard 
Acked-by: Wei Liu 
Acked-by: Thomas Gleixner 
Reviewed-by: Bill O'Donnell 
Acked-by: Baoquan He 
Acked-by: Ashutosh Dixit 
Acked-by: Anna Schumaker 
Signed-off-by: Joel Granados

cachefiles: Add auxiliary data trace

2024-12-20T21:34:05+00:00

Add a display of the first 8 bytes of the downloaded auxiliary data and of
the on-disk stored auxiliary data as these are used in coherency
management.  In the case of afs, this holds the data version number.

Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241216204124.3752367-17-dhowells@redhat.com
cc: Jeff Layton 
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner

cachefiles: Add some subrequest tracepoints

2024-12-20T21:34:05+00:00

Add some tracepoints into the cachefiles write paths.

Signed-off-by: David Howells 
Link: https://lore.kernel.org/r/20241216204124.3752367-16-dhowells@redhat.com
cc: netfs@lists.linux.dev
Signed-off-by: Christian Brauner