btrfs: raid56: extract rwm write bios assembly into a helper

The helper will be later used to refactor the rmw write 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 88e2204c9f28f3a4cbee838812c1d34686907f31..5e5bfc2c21fc1ec89b7319d1eb2804f29cfb01e1 100644 (file)
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1237,65 +1237,23 @@ static void generate_pq_vertical(struct btrfs_raid_bio *rbio, int sectornr)
                kunmap_local(pointers[stripe]);
 }
 
-/*
- * this is called from one of two situations.  We either
- * have a full stripe from the higher layers, or we've read all
- * the missing bits off disk.
- *
- * This will calculate the parity and then send down any
- * changed blocks.
- */
-static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
+static int rmw_assemble_write_bios(struct btrfs_raid_bio *rbio,
+                                  struct bio_list *bio_list)
 {
-       struct btrfs_io_context *bioc = rbio->bioc;
+       struct bio *bio;
        /* The total sector number inside the full stripe. */
        int total_sector_nr;
-       int stripe;
-       /* Sector number inside a stripe. */
        int sectornr;
-       struct bio_list bio_list;
-       struct bio *bio;
+       int stripe;
        int ret;
 
-       bio_list_init(&bio_list);
+       ASSERT(bio_list_size(bio_list) == 0);
 
        /* We should have at least one data sector. */
        ASSERT(bitmap_weight(&rbio->dbitmap, rbio->stripe_nsectors));
 
-       /* at this point we either have a full stripe,
-        * or we've read the full stripe from the drive.
-        * recalculate the parity and write the new results.
-        *
-        * We're not allowed to add any new bios to the
-        * bio list here, anyone else that wants to
-        * change this stripe needs to do their own rmw.
-        */
-       spin_lock_irq(&rbio->bio_list_lock);
-       set_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags);
-       spin_unlock_irq(&rbio->bio_list_lock);
-
-       atomic_set(&rbio->error, 0);
-
        /*
-        * now that we've set rmw_locked, run through the
-        * bio list one last time and map the page pointers
-        *
-        * We don't cache full rbios because we're assuming
-        * the higher layers are unlikely to use this area of
-        * the disk again soon.  If they do use it again,
-        * hopefully they will send another full bio.
-        */
-       index_rbio_pages(rbio);
-       if (!rbio_is_full(rbio))
-               cache_rbio_pages(rbio);
-       else
-               clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
-
-       for (sectornr = 0; sectornr < rbio->stripe_nsectors; sectornr++)
-               generate_pq_vertical(rbio, sectornr);
-
-       /*
-        * Start writing.  Make bios for everything from the higher layers (the
+        * Start assembly.  Make bios for everything from the higher layers (the
         * bio_list in our rbio) and our P/Q.  Ignore everything else.
         */
        for (total_sector_nr = 0; total_sector_nr < rbio->nr_sectors;
@@ -1317,15 +1275,16 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
                        sector = rbio_stripe_sector(rbio, stripe, sectornr);
                }
 
-               ret = rbio_add_io_sector(rbio, &bio_list, sector, stripe,
+               ret = rbio_add_io_sector(rbio, bio_list, sector, stripe,
                                         sectornr, REQ_OP_WRITE);
                if (ret)
-                       goto cleanup;
+                       goto error;
        }
 
-       if (likely(!bioc->num_tgtdevs))
-               goto write_data;
+       if (likely(!rbio->bioc->num_tgtdevs))
+               return 0;
 
+       /* Make a copy for the replace target device. */
        for (total_sector_nr = 0; total_sector_nr < rbio->nr_sectors;
             total_sector_nr++) {
                struct sector_ptr *sector;
@@ -1333,7 +1292,7 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
                stripe = total_sector_nr / rbio->stripe_nsectors;
                sectornr = total_sector_nr % rbio->stripe_nsectors;
 
-               if (!bioc->tgtdev_map[stripe]) {
+               if (!rbio->bioc->tgtdev_map[stripe]) {
                        /*
                         * We can skip the whole stripe completely, note
                         * total_sector_nr will be increased by one anyway.
@@ -1355,14 +1314,78 @@ static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
                        sector = rbio_stripe_sector(rbio, stripe, sectornr);
                }
 
-               ret = rbio_add_io_sector(rbio, &bio_list, sector,
+               ret = rbio_add_io_sector(rbio, bio_list, sector,
                                         rbio->bioc->tgtdev_map[stripe],
                                         sectornr, REQ_OP_WRITE);
                if (ret)
-                       goto cleanup;
+                       goto error;
        }
 
-write_data:
+       return 0;
+error:
+       while ((bio = bio_list_pop(bio_list)))
+               bio_put(bio);
+       return -EIO;
+}
+
+/*
+ * this is called from one of two situations.  We either
+ * have a full stripe from the higher layers, or we've read all
+ * the missing bits off disk.
+ *
+ * This will calculate the parity and then send down any
+ * changed blocks.
+ */
+static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
+{
+       /* The total sector number inside the full stripe. */
+       /* Sector number inside a stripe. */
+       int sectornr;
+       struct bio_list bio_list;
+       struct bio *bio;
+       int ret;
+
+       bio_list_init(&bio_list);
+
+       /* We should have at least one data sector. */
+       ASSERT(bitmap_weight(&rbio->dbitmap, rbio->stripe_nsectors));
+
+       /* at this point we either have a full stripe,
+        * or we've read the full stripe from the drive.
+        * recalculate the parity and write the new results.
+        *
+        * We're not allowed to add any new bios to the
+        * bio list here, anyone else that wants to
+        * change this stripe needs to do their own rmw.
+        */
+       spin_lock_irq(&rbio->bio_list_lock);
+       set_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags);
+       spin_unlock_irq(&rbio->bio_list_lock);
+
+       atomic_set(&rbio->error, 0);
+
+       /*
+        * now that we've set rmw_locked, run through the
+        * bio list one last time and map the page pointers
+        *
+        * We don't cache full rbios because we're assuming
+        * the higher layers are unlikely to use this area of
+        * the disk again soon.  If they do use it again,
+        * hopefully they will send another full bio.
+        */
+       index_rbio_pages(rbio);
+       if (!rbio_is_full(rbio))
+               cache_rbio_pages(rbio);
+       else
+               clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
+
+       for (sectornr = 0; sectornr < rbio->stripe_nsectors; sectornr++)
+               generate_pq_vertical(rbio, sectornr);
+
+       ret = rmw_assemble_write_bios(rbio, &bio_list);
+       if (ret < 0)
+               goto cleanup;
+
        atomic_set(&rbio->stripes_pending, bio_list_size(&bio_list));
        BUG_ON(atomic_read(&rbio->stripes_pending) == 0);