btrfs: remove btrfs_end_io_wq

All reads bio that go through btrfs_map_bio need to be completed in
user context.  And read I/Os are the most common and timing critical
in almost any file system workloads.

Embed a work_struct into struct btrfs_bio and use it to complete all
read bios submitted through btrfs_map, using the REQ_META flag to decide
which workqueue they are placed on.

This removes the need for a separate 128 byte allocation (typically
rounded up to 192 bytes by slab) for all reads with a size increase
of 24 bytes for struct btrfs_bio.  Future patches will reorganize
struct btrfs_bio to make use of this extra space for writes as well.

(All sizes are based a on typical 64-bit non-debug build)

Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: David Sterba <[email protected]>

1 files changed, 1 insertions, 23 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3067c966d8b6..9cce0a3228f8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2640,12 +2640,6 @@ void btrfs_submit_data_read_bio(struct inode *inode, struct bio *bio,
 		return;
 	}
 
-	ret = btrfs_bio_wq_end_io(fs_info, bio,
-			btrfs_is_free_space_inode(BTRFS_I(inode)) ?
-			BTRFS_WQ_ENDIO_FREE_SPACE : BTRFS_WQ_ENDIO_DATA);
-	if (ret)
-		goto out;
-
 	/*
 	 * Lookup bio sums does extra checks around whether we need to csum or
 	 * not, which is why we ignore skip_sum here.
@@ -7879,9 +7873,6 @@ static void submit_dio_repair_bio(struct inode *inode, struct bio *bio,
 
 	BUG_ON(bio_op(bio) == REQ_OP_WRITE);
 
-	if (btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA))
-		return;
-
 	refcount_inc(&dip->refs);
 	if (btrfs_map_bio(fs_info, bio, mirror_num))
 		refcount_dec(&dip->refs);
@@ -7970,19 +7961,12 @@ static inline blk_status_t btrfs_submit_dio_bio(struct bio *bio,
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_dio_private *dip = bio->bi_private;
-	bool write = btrfs_op(bio) == BTRFS_MAP_WRITE;
 	blk_status_t ret;
 
-	if (!write) {
-		ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
-		if (ret)
-			return ret;
-	}
-
 	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
 		goto map;
 
-	if (write) {
+	if (btrfs_op(bio) == BTRFS_MAP_WRITE) {
 		/* Check btrfs_submit_data_write_bio() for async submit rules */
 		if (async_submit && !atomic_read(&BTRFS_I(inode)->sync_writers))
 			return btrfs_wq_submit_bio(inode, bio, 0, file_offset,
@@ -10314,12 +10298,6 @@ static blk_status_t submit_encoded_read_bio(struct btrfs_inode *inode,
 			return ret;
 	}
 
-	ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
-	if (ret) {
-		btrfs_bio_free_csum(bbio);
-		return ret;
-	}
-
 	atomic_inc(&priv->pending);
 	ret = btrfs_map_bio(fs_info, bio, mirror_num);
 	if (ret) {