btrfs: raid56: fold rmw_read_wait_recover into rmw_read_bios

There is very little extra code in rmw_read_bios, and a large part of it
is the superfluous extra cleanup of the bio list.  Merge the two
functions, and only clean up the bio list after it has been added to
but before it has been emptied again by submit_read_wait_bio_list.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/raid56.c

@@ -1524,39 +1524,6 @@ static void submit_read_wait_bio_list(struct btrfs_raid_bio *rbio,
 	wait_event(rbio->io_wait, atomic_read(&rbio->stripes_pending) == 0);
 }
 
-static int rmw_assemble_read_bios(struct btrfs_raid_bio *rbio,
-				  struct bio_list *bio_list)
-{
-	int total_sector_nr;
-	int ret = 0;
-
-	ASSERT(bio_list_size(bio_list) == 0);
-
-	/*
-	 * Build a list of bios to read all sectors (including data and P/Q).
-	 *
-	 * This behavior is to compensate the later csum verification and
-	 * recovery.
-	 */
-	for (total_sector_nr = 0; total_sector_nr < rbio->nr_sectors;
-	     total_sector_nr++) {
-		struct sector_ptr *sector;
-		int stripe = total_sector_nr / rbio->stripe_nsectors;
-		int sectornr = total_sector_nr % rbio->stripe_nsectors;
-
-		sector = rbio_stripe_sector(rbio, stripe, sectornr);
-		ret = rbio_add_io_sector(rbio, bio_list, sector,
-			       stripe, sectornr, REQ_OP_READ);
-		if (ret)
-			goto cleanup;
-	}
-	return 0;
-
-cleanup:
-	bio_list_put(bio_list);
-	return ret;
-}
-
 static int alloc_rbio_data_pages(struct btrfs_raid_bio *rbio)
 {
 	const int data_pages = rbio->nr_data * rbio->stripe_npages;
@@ -2176,10 +2143,9 @@ static void fill_data_csums(struct btrfs_raid_bio *rbio)
 
 static int rmw_read_wait_recover(struct btrfs_raid_bio *rbio)
 {
-	struct bio_list bio_list;
-	int ret;
-
-	bio_list_init(&bio_list);
+	struct bio_list bio_list = BIO_EMPTY_LIST;
+	int total_sector_nr;
+	int ret = 0;
 
 	/*
 	 * Fill the data csums we need for data verification.  We need to fill
@@ -2188,21 +2154,32 @@ static int rmw_read_wait_recover(struct btrfs_raid_bio *rbio)
 	 */
 	fill_data_csums(rbio);
 
-	ret = rmw_assemble_read_bios(rbio, &bio_list);
-	if (ret < 0)
-		goto out;
+	/*
+	 * Build a list of bios to read all sectors (including data and P/Q).
+	 *
+	 * This behavior is to compensate the later csum verification and recovery.
+	 */
+	for (total_sector_nr = 0; total_sector_nr < rbio->nr_sectors;
+	     total_sector_nr++) {
+		struct sector_ptr *sector;
+		int stripe = total_sector_nr / rbio->stripe_nsectors;
+		int sectornr = total_sector_nr % rbio->stripe_nsectors;
 
-	submit_read_wait_bio_list(rbio, &bio_list);
+		sector = rbio_stripe_sector(rbio, stripe, sectornr);
+		ret = rbio_add_io_sector(rbio, &bio_list, sector,
+			       stripe, sectornr, REQ_OP_READ);
+		if (ret) {
+			bio_list_put(&bio_list);
+			return ret;
+		}
+	}
 
 	/*
 	 * We may or may not have any corrupted sectors (including missing dev
 	 * and csum mismatch), just let recover_sectors() to handle them all.
 	 */
-	ret = recover_sectors(rbio);
-	return ret;
-out:
-	bio_list_put(&bio_list);
-	return ret;
+	submit_read_wait_bio_list(rbio, &bio_list);
+	return recover_sectors(rbio);
 }
 
 static void raid_wait_write_end_io(struct bio *bio)