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fs: Add initial atomic write support info to statx

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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 <prasad.singamsetty@oracle.com>
jpg: relocate bdev support to another patch
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20240620125359.2684798-5-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Prasad Singamsetty 2024-06-20 12:53:53 +00:00 committed by Jens Axboe
parent c34fc6f26a
commit 0f9ca80fa4
4 changed files with 50 additions and 2 deletions
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34
fs/stat.c
View File

@ -89,6 +89,37 @@ void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
}
EXPORT_SYMBOL(generic_fill_statx_attr);
/**
* generic_fill_statx_atomic_writes - Fill in atomic writes statx attributes
* @stat: Where to fill in the attribute flags
* @unit_min: Minimum supported atomic write length in bytes
* @unit_max: Maximum supported atomic write length in bytes
*
* Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
* atomic write unit_min and unit_max values.
*/
void generic_fill_statx_atomic_writes(struct kstat *stat,
unsigned int unit_min,
unsigned int unit_max)
{
/* Confirm that the request type is known */
stat->result_mask |= STATX_WRITE_ATOMIC;
/* Confirm that the file attribute type is known */
stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC;
if (unit_min) {
stat->atomic_write_unit_min = unit_min;
stat->atomic_write_unit_max = unit_max;
/* Initially only allow 1x segment */
stat->atomic_write_segments_max = 1;
/* Confirm atomic writes are actually supported */
stat->attributes |= STATX_ATTR_WRITE_ATOMIC;
}
}
EXPORT_SYMBOL_GPL(generic_fill_statx_atomic_writes);
/**
* vfs_getattr_nosec - getattr without security checks
* @path: file to get attributes from
@ -659,6 +690,9 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
tmp.stx_dio_mem_align = stat->dio_mem_align;
tmp.stx_dio_offset_align = stat->dio_offset_align;
tmp.stx_subvol = stat->subvol;
tmp.stx_atomic_write_unit_min = stat->atomic_write_unit_min;
tmp.stx_atomic_write_unit_max = stat->atomic_write_unit_max;
tmp.stx_atomic_write_segments_max = stat->atomic_write_segments_max;
return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}

3
include/linux/fs.h
View File

@ -3235,6 +3235,9 @@ extern const struct inode_operations page_symlink_inode_operations;
extern void kfree_link(void *);
void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat *);
void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
void generic_fill_statx_atomic_writes(struct kstat *stat,
unsigned int unit_min,
unsigned int unit_max);
extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
void __inode_add_bytes(struct inode *inode, loff_t bytes);

3
include/linux/stat.h
View File

@ -54,6 +54,9 @@ struct kstat {
u32 dio_offset_align;
u64 change_cookie;
u64 subvol;
u32 atomic_write_unit_min;
u32 atomic_write_unit_max;
u32 atomic_write_segments_max;
};
/* These definitions are internal to the kernel for now. Mainly used by nfsd. */

12
include/uapi/linux/stat.h
View File

@ -126,9 +126,15 @@ struct statx {
__u64 stx_mnt_id;
__u32 stx_dio_mem_align; /* Memory buffer alignment for direct I/O */
__u32 stx_dio_offset_align; /* File offset alignment for direct I/O */
__u64 stx_subvol; /* Subvolume identifier */
/* 0xa0 */
__u64 __spare3[11]; /* Spare space for future expansion */
__u64 stx_subvol; /* Subvolume identifier */
__u32 stx_atomic_write_unit_min; /* Min atomic write unit in bytes */
__u32 stx_atomic_write_unit_max; /* Max atomic write unit in bytes */
/* 0xb0 */
__u32 stx_atomic_write_segments_max; /* Max atomic write segment count */
__u32 __spare1[1];
/* 0xb8 */
__u64 __spare3[9]; /* Spare space for future expansion */
/* 0x100 */
};
@ -157,6 +163,7 @@ struct statx {
#define STATX_DIOALIGN 0x00002000U /* Want/got direct I/O alignment info */
#define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */
#define STATX_SUBVOL 0x00008000U /* Want/got stx_subvol */
#define STATX_WRITE_ATOMIC 0x00010000U /* Want/got atomic_write_* fields */
#define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */
@ -192,6 +199,7 @@ struct statx {
#define STATX_ATTR_MOUNT_ROOT 0x00002000 /* Root of a mount */
#define STATX_ATTR_VERITY 0x00100000 /* [I] Verity protected file */
#define STATX_ATTR_DAX 0x00200000 /* File is currently in DAX state */
#define STATX_ATTR_WRITE_ATOMIC 0x00400000 /* File supports atomic write operations */
#endif /* _UAPI_LINUX_STAT_H */