block: expose write streams for block device nodes

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>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20250506121732.8211-6-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/fops.c b/block/fops.c
index b6d7cdd96b54b85076db7d9431a8818b102b1389..1309861d4c2c4b88be375136eb83e34299ef7616 100644 (file)
--- 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))