btrfs: split bios to the fs sector size boundary

commit be691b5e593f2cc8cef67bbc59c1fb91b74a86a9 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index 7e0f9600b80c43647c3fac55ddab013b510c2ad8..3d2376caedfa68841423a9a39262aba9689a934c 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;
 }