[PATCH v6 06/13] xfs: switch atomic write size check in xfs_file_write_iter()

From: John Garry
Date: Thu Mar 13 2025 - 13:15:28 EST


Currently the size of atomic write allowed is fixed at the blocksize.

To start to lift this restriction, partly refactor
xfs_report_atomic_write() to into helpers -
xfs_get_atomic_write_{min, max}_attr() - and use those helpers to find the
per-inode atomic write limits and check according to that.

Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
fs/xfs/xfs_file.c | 12 +++++-------
fs/xfs/xfs_iops.c | 28 +++++++++++++++++++++++-----
fs/xfs/xfs_iops.h | 2 ++
3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index fe8cf9d96eb0..7a56ddb86fd2 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1032,14 +1032,12 @@ xfs_file_write_iter(
return xfs_file_dax_write(iocb, from);

if (iocb->ki_flags & IOCB_ATOMIC) {
- /*
- * Currently only atomic writing of a single FS block is
- * supported. It would be possible to atomic write smaller than
- * a FS block, but there is no requirement to support this.
- * Note that iomap also does not support this yet.
- */
- if (ocount != ip->i_mount->m_sb.sb_blocksize)
+ if (ocount < xfs_get_atomic_write_min_attr(ip))
return -EINVAL;
+
+ if (ocount > xfs_get_atomic_write_max_attr(ip))
+ return -EINVAL;
+
ret = generic_atomic_write_valid(iocb, from);
if (ret)
return ret;
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 444193f543ef..64b1f8c73824 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -601,16 +601,34 @@ xfs_report_dioalign(
stat->dio_offset_align = stat->dio_read_offset_align;
}

+unsigned int
+xfs_get_atomic_write_min_attr(
+ struct xfs_inode *ip)
+{
+ if (!xfs_inode_can_atomicwrite(ip))
+ return 0;
+
+ return ip->i_mount->m_sb.sb_blocksize;
+}
+
+unsigned int
+xfs_get_atomic_write_max_attr(
+ struct xfs_inode *ip)
+{
+ if (!xfs_inode_can_atomicwrite(ip))
+ return 0;
+
+ return ip->i_mount->m_sb.sb_blocksize;
+}
+
static void
xfs_report_atomic_write(
struct xfs_inode *ip,
struct kstat *stat)
{
- unsigned int unit_min = 0, unit_max = 0;
-
- if (xfs_inode_can_atomicwrite(ip))
- unit_min = unit_max = ip->i_mount->m_sb.sb_blocksize;
- generic_fill_statx_atomic_writes(stat, unit_min, unit_max);
+ generic_fill_statx_atomic_writes(stat,
+ xfs_get_atomic_write_min_attr(ip),
+ xfs_get_atomic_write_max_attr(ip));
}

STATIC int
diff --git a/fs/xfs/xfs_iops.h b/fs/xfs/xfs_iops.h
index 3c1a2605ffd2..3ef3bb632ad8 100644
--- a/fs/xfs/xfs_iops.h
+++ b/fs/xfs/xfs_iops.h
@@ -19,5 +19,7 @@ int xfs_inode_init_security(struct inode *inode, struct inode *dir,
extern void xfs_setup_inode(struct xfs_inode *ip);
extern void xfs_setup_iops(struct xfs_inode *ip);
extern void xfs_diflags_to_iflags(struct xfs_inode *ip, bool init);
+unsigned int xfs_get_atomic_write_min_attr(struct xfs_inode *ip);
+unsigned int xfs_get_atomic_write_max_attr(struct xfs_inode *ip);

#endif /* __XFS_IOPS_H__ */
--
2.31.1