linux-toradex.git/include/linux/stat.h, branch v6.16-rc6

fs: add atomic write unit max opt to statx

2025-05-07T21:25:30+00:00

XFS will be able to support large atomic writes (atomic write > 1x block)
in future. This will be achieved by using different operating methods,
depending on the size of the write.

Specifically a new method of operation based in FS atomic extent remapping
will be supported in addition to the current HW offload-based method.

The FS method will generally be appreciably slower performing than the
HW-offload method. However the FS method will be typically able to
contribute to achieving a larger atomic write unit max limit.

XFS will support a hybrid mode, where HW offload method will be used when
possible, i.e. HW offload is used when the length of the write is
supported, and for other times FS-based atomic writes will be used.

As such, there is an atomic write length at which the user may experience
appreciably slower performance.

Advertise this limit in a new statx field, stx_atomic_write_unit_max_opt.

When zero, it means that there is no such performance boundary.

Masks STATX{_ATTR}_WRITE_ATOMIC can be used to get this new field. This is
ok for older kernels which don't support this new field, as they would
report 0 in this field (from zeroing in cp_statx()) already. Furthermore
those older kernels don't support large atomic writes - apart from block
fops, but there would be consistent performance there for atomic writes
in range [unit min, unit max].

Reviewed-by: Darrick J. Wong 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Darrick J. Wong 
Acked-by: Darrick J. Wong 
Signed-off-by: John Garry

fs: pack struct kstat better

2025-01-29T17:04:28+00:00

Move the change_cookie and subvol up to avoid two 4 byte holes.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

fs: add STATX_DIO_READ_ALIGN

2025-01-09T15:23:17+00:00

Add a separate dio read align field, as many out of place write
file systems can easily do reads aligned to the device sector size,
but require bigger alignment for writes.

This is usually papered over by falling back to buffered I/O for smaller
writes and doing read-modify-write cycles, but performance for this
sucks, so applications benefit from knowing the actual write alignment.

Signed-off-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20250109083109.1441561-3-hch@lst.de
Reviewed-by: John Garry 
Reviewed-by: Jan Kara 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Christian Brauner

fs: Add initial atomic write support info to statx

2024-06-20T21:19:17+00:00

Extend statx system call to return additional info for atomic write support
support for a file.

Helper function generic_fill_statx_atomic_writes() can be used by FSes to
fill in the relevant statx fields. For now atomic_write_segments_max will
always be 1, otherwise some rules would need to be imposed on iovec length
and alignment, which we don't want now.

Signed-off-by: Prasad Singamsetty 
jpg: relocate bdev support to another patch
Reviewed-by: Darrick J. Wong 
Reviewed-by: Martin K. Petersen 
Signed-off-by: John Garry 
Acked-by: Darrick J. Wong 
Link: https://lore.kernel.org/r/20240620125359.2684798-5-john.g.garry@oracle.com
Signed-off-by: Jens Axboe

statx: stx_subvol

2024-03-26T08:01:18+00:00

Add a new statx field for (sub)volume identifiers, as implemented by
btrfs and bcachefs.

This includes bcachefs support; we'll definitely want btrfs support as
well.

Link: https://lore.kernel.org/linux-fsdevel/2uvhm6gweyl7iyyp2xpfryvcu2g3padagaeqcbiavjyiis6prl@yjm725bizncq/
Signed-off-by: Kent Overstreet 
Cc: Josef Bacik 
Cc: Miklos Szeredi 
Cc: Christian Brauner 
Cc: David Howells 
Signed-off-by: Kent Overstreet 
Link: https://lore.kernel.org/r/20240308022914.196982-1-kent.overstreet@linux.dev
Signed-off-by: Johannes Thumshirn 
Signed-off-by: Christian Brauner

vfs: plumb i_version handling into struct kstat

2023-01-26T12:00:06+00:00

The NFS server has a lot of special handling for different types of
change attribute access, depending on the underlying filesystem. In
most cases, it's doing a getattr anyway and then fetching that value
after the fact.

Rather that do that, add a new STATX_CHANGE_COOKIE flag that is a
kernel-only symbol (for now). If requested and getattr can implement it,
it can fill out this field. For IS_I_VERSION inodes, add a generic
implementation in vfs_getattr_nosec. Take care to mask
STATX_CHANGE_COOKIE off in requests from userland and in the result
mask.

Since not all filesystems can give the same guarantees of monotonicity,
claim a STATX_ATTR_CHANGE_MONOTONIC flag that filesystems can set to
indicate that they offer an i_version value that can never go backward.

Eventually if we decide to make the i_version available to userland, we
can just designate a field for it in struct statx, and move the
STATX_CHANGE_COOKIE definition to the uapi header.

Reviewed-by: NeilBrown 
Reviewed-by: Jan Kara 
Signed-off-by: Jeff Layton

statx: add direct I/O alignment information

2022-09-12T00:47:04+00:00

Traditionally, the conditions for when DIO (direct I/O) is supported
were fairly simple.  For both block devices and regular files, DIO had
to be aligned to the logical block size of the block device.

However, due to filesystem features that have been added over time (e.g.
multi-device support, data journalling, inline data, encryption, verity,
compression, checkpoint disabling, log-structured mode), the conditions
for when DIO is allowed on a regular file have gotten increasingly
complex.  Whether a particular regular file supports DIO, and with what
alignment, can depend on various file attributes and filesystem mount
options, as well as which block device(s) the file's data is located on.

Moreover, the general rule of DIO needing to be aligned to the block
device's logical block size was recently relaxed to allow user buffers
(but not file offsets) aligned to the DMA alignment instead.  See
commit bf8d08532bc1 ("iomap: add support for dma aligned direct-io").

XFS has an ioctl XFS_IOC_DIOINFO that exposes DIO alignment information.
Uplifting this to the VFS is one possibility.  However, as discussed
(https://lore.kernel.org/linux-fsdevel/20220120071215.123274-1-ebiggers@kernel.org/T/#u),
this ioctl is rarely used and not known to be used outside of
XFS-specific code.  It was also never intended to indicate when a file
doesn't support DIO at all, nor was it intended for block devices.

Therefore, let's expose this information via statx().  Add the
STATX_DIOALIGN flag and two new statx fields associated with it:

* stx_dio_mem_align: the alignment (in bytes) required for user memory
  buffers for DIO, or 0 if DIO is not supported on the file.

* stx_dio_offset_align: the alignment (in bytes) required for file
  offsets and I/O segment lengths for DIO, or 0 if DIO is not supported
  on the file.  This will only be nonzero if stx_dio_mem_align is
  nonzero, and vice versa.

Note that as with other statx() extensions, if STATX_DIOALIGN isn't set
in the returned statx struct, then these new fields won't be filled in.
This will happen if the file is neither a regular file nor a block
device, or if the file is a regular file and the filesystem doesn't
support STATX_DIOALIGN.  It might also happen if the caller didn't
include STATX_DIOALIGN in the request mask, since statx() isn't required
to return unrequested information.

This commit only adds the VFS-level plumbing for STATX_DIOALIGN.  For
regular files, individual filesystems will still need to add code to
support it.  For block devices, a separate commit will wire it up too.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Christian Brauner (Microsoft) 
Signed-off-by: Eric Biggers 
Link: https://lore.kernel.org/r/20220827065851.135710-2-ebiggers@kernel.org

fs: add generic helper for filling statx attribute flags

2021-08-17T09:47:43+00:00

The immutable and append-only properties on an inode are published on
the inode's i_flags and enforced by the VFS.

Create a helper to fill the corresponding STATX_ATTR_ flags in the kstat
structure from the inode's i_flags.

Only orange was converted to use this helper.
Other filesystems could use it in the future.

Suggested-by: Miklos Szeredi 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

fs: remove KSTAT_QUERY_FLAGS

2020-09-27T02:55:05+00:00

KSTAT_QUERY_FLAGS expands to AT_STATX_SYNC_TYPE, which itself already
is a mask.  Remove the double name, especially given that the prefix
is a little confusing vs the normal AT_* flags.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

statx: add mount ID

2020-05-14T14:44:24+00:00

Systemd is hacking around to get it and it's trivial to add to statx, so...

Cc: linux-api@vger.kernel.org
Cc: linux-man@vger.kernel.org
Signed-off-by: Miklos Szeredi 
Reviewed-by: Christoph Hellwig