btrfs: split bios to the fs sector size boundary

Btrfs like other file systems can't really deal with I/O not aligned to
it's internal block size (which strangely is called sector size in
btrfs, for historical reasons), but the block layer split helper doesn't
even know about that.

Round down the split boundary so that all I/Os are aligned.

Fixes: d5e4377d5051 ("btrfs: split zone append bios in btrfs_submit_bio")
CC: stable@vger.kernel.org # 6.12
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index 011cc97be3b573337e095adfc05c1f09862e85c2..78f5606baacb54528dae502238e07193fc6fc505 100644 (file)
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -649,8 +649,14 @@ static u64 btrfs_append_map_length(struct btrfs_bio *bbio, u64 map_length)
        map_length = min(map_length, bbio->fs_info->max_zone_append_size);
        sector_offset = bio_split_rw_at(&bbio->bio, &bbio->fs_info->limits,
                                        &nr_segs, map_length);
-       if (sector_offset)
-               return sector_offset << SECTOR_SHIFT;
+       if (sector_offset) {
+               /*
+                * bio_split_rw_at() could split at a size smaller than our
+                * sectorsize and thus cause unaligned I/Os.  Fix that by
+                * always rounding down to the nearest boundary.
+                */
+               return ALIGN_DOWN(sector_offset << SECTOR_SHIFT, bbio->fs_info->sectorsize);
+       }
        return map_length;
 }