[PATCH v5 8/8] xfs: support hardware write streams

[Kanchan Joshi <joshi.k@samsung.com>]

Use the stream count reported by the data and realtime block devices
where they have one, falling back to the geometry-derived count. The
count is capped at the group count so that every stream backs onto at
least one group; a device with more streams than the filesystem has
groups loses the excess, so mkfs should create at least as many groups
as the device has streams.

Set iomap->write_stream from the inode so that the id reaches the
device.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
---
 fs/xfs/xfs_buf.c   | 7 ++++++-
 fs/xfs/xfs_iomap.c | 1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 4e84528b05cb..1748be9aa7d6 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1709,8 +1709,13 @@ xfs_buftarg_init_streams(
 	unsigned int		nr_groups)
 {
 	unsigned int		nr_streams;
+	unsigned int		hw_streams;
 
-	nr_streams = xfs_sw_write_stream_count(nr_groups);
+	hw_streams = bdev_max_write_streams(btp->bt_bdev);
+	if (hw_streams)
+		nr_streams = min(hw_streams, nr_groups);
+	else
+		nr_streams = xfs_sw_write_stream_count(nr_groups);
 	return write_stream_pool_init(&btp->bt_stream_pool, nr_streams);
 }
 
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 7c6238fed61e..3e9df790a544 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -144,6 +144,7 @@ xfs_bmbt_to_iomap(
 	}
 	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
 	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
+	iomap->write_stream = READ_ONCE(VFS_I(ip)->i_write_stream);
 	if (mapping_flags & IOMAP_DAX) {
 		iomap->dax_dev = target->bt_daxdev;
 	} else {
-- 
2.25.1