[PATCH v2 5/7] xfs: Switch atomic write size check in xfs_file_write_iter()

[John Garry <john.g.garry@oracle.com>]

Currently atomic writes size permitted is fixed at the blocksize.

To start to remove this restriction, use xfs_get_atomic_write_attr() to
find the per-inode atomic write limits and check according to that.

Signed-off-by: John Garry <john.g.garry@oracle.com>
---
 fs/xfs/xfs_file.c | 12 +++++-------
 fs/xfs/xfs_iops.c |  2 +-
 fs/xfs/xfs_iops.h |  2 ++
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index f2b2eb2dee94..8420c7a9f2a5 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -938,14 +938,12 @@ 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)
+		unsigned int unit_min, unit_max;
+
+		xfs_get_atomic_write_attr(ip, &unit_min, &unit_max);
+		if (ocount < unit_min || ocount > unit_max)
 			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 207e0dadffc3..883ec45ae708 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -572,7 +572,7 @@ xfs_stat_blksize(
 	return max_t(uint32_t, PAGE_SIZE, mp->m_sb.sb_blocksize);
 }
 
-static void
+void
 xfs_get_atomic_write_attr(
 	struct xfs_inode	*ip,
 	unsigned int		*unit_min,
diff --git a/fs/xfs/xfs_iops.h b/fs/xfs/xfs_iops.h
index 3c1a2605ffd2..82d3ffbf7024 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);
+extern void xfs_get_atomic_write_attr(struct xfs_inode	*ip,
+		unsigned int *unit_min, unsigned int *unit_max);
 
 #endif /* __XFS_IOPS_H__ */
-- 
2.31.1