btrfs: give struct btrfs_bio a real end_io handler

Currently btrfs_bio end I/O handling is a bit of a mess.  The bi_end_io
handler and bi_private pointer of the embedded struct bio are both used
to handle the completion of the high-level btrfs_bio and for the I/O
completion for the low-level device that the embedded bio ends up being
sent to.

To support this bi_end_io and bi_private are saved into the
btrfs_io_context structure and then restored after the bio sent to the
underlying device has completed the actual I/O.

Untangle this by adding an end I/O handler and private data to struct
btrfs_bio for the high-level btrfs_bio based completions, and leave the
actual bio bi_end_io handler and bi_private pointer entirely to the
low-level device I/O.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 56fc01373b0f..f19a1cd1bfcf 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -361,6 +361,8 @@ struct btrfs_fs_devices {
  */
 #define BTRFS_MAX_BIO_SECTORS				(256)
 
+typedef void (*btrfs_bio_end_io_t)(struct btrfs_bio *bbio);
+
 /*
  * Additional info to pass along bio.
  *
@@ -378,6 +380,10 @@ struct btrfs_bio {
 	u8 csum_inline[BTRFS_BIO_INLINE_CSUM_SIZE];
 	struct bvec_iter iter;
 
+	/* End I/O information supplied to btrfs_bio_alloc */
+	btrfs_bio_end_io_t end_io;
+	void *private;
+
 	/* For read end I/O handling */
 	struct work_struct end_io_work;
 
@@ -396,8 +402,16 @@ static inline struct btrfs_bio *btrfs_bio(struct bio *bio)
 int __init btrfs_bioset_init(void);
 void __cold btrfs_bioset_exit(void);
 
-struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf);
-struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size);
+struct bio *btrfs_bio_alloc(unsigned int nr_vecs, blk_opf_t opf,
+			    btrfs_bio_end_io_t end_io, void *private);
+struct bio *btrfs_bio_clone_partial(struct bio *orig, u64 offset, u64 size,
+				    btrfs_bio_end_io_t end_io, void *private);
+
+static inline void btrfs_bio_end_io(struct btrfs_bio *bbio, blk_status_t status)
+{
+	bbio->bio.bi_status = status;
+	bbio->end_io(bbio);
+}
 
 static inline void btrfs_bio_free_csum(struct btrfs_bio *bbio)
 {
@@ -459,9 +473,7 @@ struct btrfs_io_context {
 	refcount_t refs;
 	struct btrfs_fs_info *fs_info;
 	u64 map_type; /* get from map_lookup->type */
-	bio_end_io_t *end_io;
 	struct bio *orig_bio;
-	void *private;
 	atomic_t error;
 	int max_errors;
 	int num_stripes;