[PATCHv2 05/11] block: expose write streams for block device nodes

Keith Busch
2025-02-03T18:46:56Z

From: Christoph Hellwig <hch@lst.de>

Use the per-kiocb write stream if provided, or map temperature hints to
write streams (which is a bit questionable, but this shows how it is
done).

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[kbusch: removed statx reporting]
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
block/fops.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/block/fops.c b/block/fops.c
index be9f1dbea9ce0..11902b7120af2 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -73,6 +73,7 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
}
bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
bio.bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
+ bio.bi_write_stream = iocb->ki_write_stream;
bio.bi_ioprio = iocb->ki_ioprio;
if (iocb->ki_flags & IOCB_ATOMIC)
bio.bi_opf |= REQ_ATOMIC;
@@ -206,6 +207,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
for (;;) {
bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
bio->bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
+ bio->bi_write_stream = iocb->ki_write_stream;
bio->bi_private = dio;
bio->bi_end_io = blkdev_bio_end_io;
bio->bi_ioprio = iocb->ki_ioprio;
@@ -333,6 +335,7 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
dio->iocb = iocb;
bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
bio->bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
+ bio->bi_write_stream = iocb->ki_write_stream;
bio->bi_end_io = blkdev_bio_end_io_async;
bio->bi_ioprio = iocb->ki_ioprio;

@@ -398,6 +401,26 @@ static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
if (blkdev_dio_invalid(bdev, iocb, iter))
return -EINVAL;

+ if (iov_iter_rw(iter) == WRITE) {
+ u16 max_write_streams = bdev_max_write_streams(bdev);
+
+ if (iocb->ki_write_stream) {
+ if (iocb->ki_write_stream > max_write_streams)
+ return -EINVAL;
+ } else if (max_write_streams) {
+ enum rw_hint write_hint =
+ file_inode(iocb->ki_filp)->i_write_hint;
+
+ /*
+ * Just use the write hint as write stream for block
+ * device writes. This assumes no file system is
+ * mounted that would use the streams differently.
+ */
+ if (write_hint <= max_write_streams)
+ iocb->ki_write_stream = write_hint;
+ }
+ }
+
nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
if (likely(nr_pages <= BIO_MAX_VECS)) {
if (is_sync_kiocb(iocb))
--
2.43.5