kernel/linux.git/include/uapi/linux/stat.h, branch v6.12.80

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

add unique mount ID

2023-11-18T13:56:16+00:00

If a mount is released then its mnt_id can immediately be reused. This is bad news for user interfaces that want to uniquely identify a mount. Implementing a unique mount ID is trivial (use a 64bit counter). Unfortunately userspace assumes 32bit size and would overflow after the counter reaches 2^32. Introduce a new 64bit ID alongside the old one. Initialize the counter to 2^32, this guarantees that the old and new IDs are never mixed up. Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/r/20231025140205.3586473-2-mszeredi@redhat.com Reviewed-by: Ian Kent Signed-off-by: Christian Brauner

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

uapi: fix statx attribute value overlap for DAX & MOUNT_ROOT

2020-12-03T18:03:14+00:00

STATX_ATTR_MOUNT_ROOT and STATX_ATTR_DAX got merged with the same value, so one of them needs fixing. Move STATX_ATTR_DAX. While we're in here, clarify the value-matching scheme for some of the attributes, and explain why the value for DAX does not match. Fixes: 80340fe3605c ("statx: add mount_root") Fixes: 712b2698e4c0 ("fs/stat: Define DAX statx attribute") Link: https://lore.kernel.org/linux-fsdevel/7027520f-7c79-087e-1d00-743bdefa1a1e@redhat.com/ Link: https://lore.kernel.org/lkml/20201202214629.1563760-1-ira.weiny@intel.com/ Reported-by: David Howells Signed-off-by: Eric Sandeen Reviewed-by: David Howells Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Reviewed-by: Ira Weiny Cc: # 5.8 Signed-off-by: Linus Torvalds

Merge tag 'vfs-5.8-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

2020-06-03T02:45:12+00:00

Pull DAX updates part one from Darrick Wong: "After many years of LKML-wrangling about how to enable programs to query and influence the file data access mode (DAX) when a filesystem resides on storage devices such as persistent memory, Ira Weiny has emerged with a proposed set of standard behaviors that has not been shot down by anyone! We're more or less standardizing on the current XFS behavior and adapting ext4 to do the same. This is the first of a handful pull requests that will make ext4 and XFS present a consistent interface for user programs that care about DAX. We add a statx attribute that programs can check to see if DAX is enabled on a particular file. Then, we update the DAX documentation to spell out the user-visible behaviors that filesystems will guarantee (until the next storage industry shakeup). The on-disk inode flag has been in XFS for a few years now. Summary: - Clean up io_is_direct. - Add a new statx flag to indicate when file data access is being done via DAX (as opposed to the page cache). - Update the documentation for how system administrators and application programmers can take advantage of the (still experimental DAX) feature" Link: https://lore.kernel.org/lkml/20200505002016.1085071-1-ira.weiny@intel.com/ * tag 'vfs-5.8-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: Documentation/dax: Update Usage section fs/stat: Define DAX statx attribute fs: Remove unneeded IS_DAX() check in io_is_direct()

statx: add mount_root

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

Determining whether a path or file descriptor refers to a mountpoint (or more precisely a mount root) is not trivial using current tools. Add a flag to statx that indicates whether the path or fd refers to the root of a mount or not. Cc: linux-api@vger.kernel.org Cc: linux-man@vger.kernel.org Reported-by: Lennart Poettering Reported-by: J. Bruce Fields Signed-off-by: Miklos Szeredi Reviewed-by: Christoph Hellwig

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

uapi: deprecate STATX_ALL

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

Constants of the *_ALL type can be actively harmful due to the fact that developers will usually fail to consider the possible effects of future changes to the definition. Deprecate STATX_ALL in the uapi, while no damage has been done yet. We could keep something like this around in the kernel, but there's actually no point, since all filesystems should be explicitly checking flags that they support and not rely on the VFS masking unknown ones out: a flag could be known to the VFS, yet not known to the filesystem. Cc: David Howells Cc: linux-api@vger.kernel.org Cc: linux-man@vger.kernel.org Signed-off-by: Miklos Szeredi Reviewed-by: Christoph Hellwig

fs/stat: Define DAX statx attribute

2020-05-04T15:49:39+00:00

In order for users to determine if a file is currently operating in DAX state (effective DAX). Define a statx attribute value and set that attribute if the effective DAX flag is set. To go along with this we propose the following addition to the statx man page: STATX_ATTR_DAX The file is in the DAX (cpu direct access) state. DAX state attempts to minimize software cache effects for both I/O and memory mappings of this file. It requires a file system which has been configured to support DAX. DAX generally assumes all accesses are via cpu load / store instructions which can minimize overhead for small accesses, but may adversely affect cpu utilization for large transfers. File I/O is done directly to/from user-space buffers and memory mapped I/O may be performed with direct memory mappings that bypass kernel page cache. While the DAX property tends to result in data being transferred synchronously, it does not give the same guarantees of O_SYNC where data and the necessary metadata are transferred together. A DAX file may support being mapped with the MAP_SYNC flag, which enables a program to use CPU cache flush instructions to persist CPU store operations without an explicit fsync(2). See mmap(2) for more information. Reviewed-by: Dave Chinner Reviewed-by: Jan Kara Reviewed-by: Darrick J. Wong Signed-off-by: Ira Weiny Signed-off-by: Darrick J. Wong