btrfs: never return true for reads in btrfs_use_zone_append

Using Zone Append only makes sense for writes to the device, so check
that in btrfs_use_zone_append.  This avoids the possibility of
artificially limited read size on zoned file systems.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 8824748..442bb79 100644 (file)
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1641,6 +1641,9 @@ bool btrfs_use_zone_append(struct btrfs_bio *bbio)
        if (!is_data_inode(&inode->vfs_inode))
                return false;
 
+       if (btrfs_op(&bbio->bio) != BTRFS_MAP_WRITE)
+               return false;
+
        /*
         * Using REQ_OP_ZONE_APPNED for relocation can break assumptions on the
         * extent layout the relocation code has.