1 files changed, 71 insertions, 5 deletions

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 756bd3ca8e00..8cddbb7c149b 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -601,16 +601,82 @@ xfs_report_dioalign(
 		stat->dio_offset_align = stat->dio_read_offset_align;
 }
 
+unsigned int
+xfs_get_atomic_write_min(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	/*
+	 * If we can complete an atomic write via atomic out of place writes,
+	 * then advertise a minimum size of one fsblock.  Without this
+	 * mechanism, we can only guarantee atomic writes up to a single LBA.
+	 *
+	 * If out of place writes are not available, we can guarantee an atomic
+	 * write of exactly one single fsblock if the bdev will make that
+	 * guarantee for us.
+	 */
+	if (xfs_inode_can_hw_atomic_write(ip) || xfs_can_sw_atomic_write(mp))
+		return mp->m_sb.sb_blocksize;
+
+	return 0;
+}
+
+unsigned int
+xfs_get_atomic_write_max(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	/*
+	 * If out of place writes are not available, we can guarantee an atomic
+	 * write of exactly one single fsblock if the bdev will make that
+	 * guarantee for us.
+	 */
+	if (!xfs_can_sw_atomic_write(mp)) {
+		if (xfs_inode_can_hw_atomic_write(ip))
+			return mp->m_sb.sb_blocksize;
+		return 0;
+	}
+
+	/*
+	 * If we can complete an atomic write via atomic out of place writes,
+	 * then advertise a maximum size of whatever we can complete through
+	 * that means.  Hardware support is reported via max_opt, not here.
+	 */
+	if (XFS_IS_REALTIME_INODE(ip))
+		return XFS_FSB_TO_B(mp, mp->m_groups[XG_TYPE_RTG].awu_max);
+	return XFS_FSB_TO_B(mp, mp->m_groups[XG_TYPE_AG].awu_max);
+}
+
+unsigned int
+xfs_get_atomic_write_max_opt(
+	struct xfs_inode	*ip)
+{
+	unsigned int		awu_max = xfs_get_atomic_write_max(ip);
+
+	/* if the max is 1x block, then just keep behaviour that opt is 0 */
+	if (awu_max <= ip->i_mount->m_sb.sb_blocksize)
+		return 0;
+
+	/*
+	 * Advertise the maximum size of an atomic write that we can tell the
+	 * block device to perform for us.  In general the bdev limit will be
+	 * less than our out of place write limit, but we don't want to exceed
+	 * the awu_max.
+	 */
+	return min(awu_max, xfs_inode_buftarg(ip)->bt_bdev_awu_max);
+}
+
 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(ip),
+			xfs_get_atomic_write_max(ip),
+			xfs_get_atomic_write_max_opt(ip));
 }
 
 STATIC int