btrfs: raid56: extract the rmw bio list build code into a helper

The helper will later be used to refactor the whole RMW path.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 2dd87ceda9db9c893576fa6e6f673f579484f154..88e2204c9f28f3a4cbee838812c1d34686907f31 100644 (file)
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1595,28 +1595,16 @@ static void raid56_rmw_end_io_work(struct work_struct *work)
        validate_rbio_for_rmw(rbio);
 }
 
-/*
- * the stripe must be locked by the caller.  It will
- * unlock after all the writes are done
- */
-static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio)
+static int rmw_assemble_read_bios(struct btrfs_raid_bio *rbio,
+                                 struct bio_list *bio_list)
 {
-       int bios_to_read = 0;
-       struct bio_list bio_list;
        const int nr_data_sectors = rbio->stripe_nsectors * rbio->nr_data;
-       int ret;
-       int total_sector_nr;
        struct bio *bio;
+       int total_sector_nr;
+       int ret = 0;
 
-       bio_list_init(&bio_list);
-
-       ret = alloc_rbio_pages(rbio);
-       if (ret)
-               goto cleanup;
-
-       index_rbio_pages(rbio);
+       ASSERT(bio_list_size(bio_list) == 0);
 
-       atomic_set(&rbio->error, 0);
        /* Build a list of bios to read all the missing data sectors. */
        for (total_sector_nr = 0; total_sector_nr < nr_data_sectors;
             total_sector_nr++) {
@@ -1641,11 +1629,43 @@ static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio)
                if (sector->uptodate)
                        continue;
 
-               ret = rbio_add_io_sector(rbio, &bio_list, sector,
+               ret = rbio_add_io_sector(rbio, bio_list, sector,
                               stripe, sectornr, REQ_OP_READ);
                if (ret)
                        goto cleanup;
        }
+       return 0;
+
+cleanup:
+       while ((bio = bio_list_pop(bio_list)))
+               bio_put(bio);
+       return ret;
+}
+
+/*
+ * the stripe must be locked by the caller.  It will
+ * unlock after all the writes are done
+ */
+static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio)
+{
+       int bios_to_read = 0;
+       struct bio_list bio_list;
+       int ret;
+       struct bio *bio;
+
+       bio_list_init(&bio_list);
+
+       ret = alloc_rbio_pages(rbio);
+       if (ret)
+               goto cleanup;
+
+       index_rbio_pages(rbio);
+
+       atomic_set(&rbio->error, 0);
+
+       ret = rmw_assemble_read_bios(rbio, &bio_list);
+       if (ret < 0)
+               goto cleanup;
 
        bios_to_read = bio_list_size(&bio_list);
        if (!bios_to_read) {