btrfs: combine device update operations during transaction commit

We currently overload the pending_chunks list to handle updating
btrfs_device->commit_bytes used.  We don't actually care about the
extent mapping or even the device mapping for the chunk - we just need
the device, and we can end up processing it multiple times.  The
fs_devices->resized_list does more or less the same thing, but with the
disk size.  They are called consecutively during commit and have more or
less the same purpose.

We can combine the two lists into a single list that attaches to the
transaction and contains a list of devices that need updating.  Since we
always add the device to a list when we change bytes_used or
disk_total_size, there's no harm in copying both values at once.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 36 insertions, 51 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 77bca3a61e26..72e069c227ab 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -319,7 +319,6 @@ static struct btrfs_fs_devices *alloc_fs_devices(const u8 *fsid,
 	mutex_init(&fs_devs->device_list_mutex);
 
 	INIT_LIST_HEAD(&fs_devs->devices);
-	INIT_LIST_HEAD(&fs_devs->resized_devices);
 	INIT_LIST_HEAD(&fs_devs->alloc_list);
 	INIT_LIST_HEAD(&fs_devs->fs_list);
 	if (fsid)
@@ -335,6 +334,7 @@ static struct btrfs_fs_devices *alloc_fs_devices(const u8 *fsid,
 
 void btrfs_free_device(struct btrfs_device *device)
 {
+	WARN_ON(!list_empty(&device->post_commit_list));
 	rcu_string_free(device->name);
 	bio_put(device->flush_bio);
 	kfree(device);
@@ -403,7 +403,7 @@ static struct btrfs_device *__alloc_device(void)
 
 	INIT_LIST_HEAD(&dev->dev_list);
 	INIT_LIST_HEAD(&dev->dev_alloc_list);
-	INIT_LIST_HEAD(&dev->resized_list);
+	INIT_LIST_HEAD(&dev->post_commit_list);
 
 	spin_lock_init(&dev->io_lock);
 
@@ -2853,7 +2853,6 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_fs_info *fs_info = device->fs_info;
 	struct btrfs_super_block *super_copy = fs_info->super_copy;
-	struct btrfs_fs_devices *fs_devices;
 	u64 old_total;
 	u64 diff;
 
@@ -2872,8 +2871,6 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 		return -EINVAL;
 	}
 
-	fs_devices = fs_info->fs_devices;
-
 	btrfs_set_super_total_bytes(super_copy,
 			round_down(old_total + diff, fs_info->sectorsize));
 	device->fs_devices->total_rw_bytes += diff;
@@ -2881,9 +2878,9 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 	btrfs_device_set_total_bytes(device, new_size);
 	btrfs_device_set_disk_total_bytes(device, new_size);
 	btrfs_clear_space_info_full(device->fs_info);
-	if (list_empty(&device->resized_list))
-		list_add_tail(&device->resized_list,
-			      &fs_devices->resized_devices);
+	if (list_empty(&device->post_commit_list))
+		list_add_tail(&device->post_commit_list,
+			      &trans->transaction->dev_update_list);
 	mutex_unlock(&fs_info->chunk_mutex);
 
 	return btrfs_update_device(trans, device);
@@ -4872,9 +4869,9 @@ again:
 	}
 
 	btrfs_device_set_disk_total_bytes(device, new_size);
-	if (list_empty(&device->resized_list))
-		list_add_tail(&device->resized_list,
-			      &fs_info->fs_devices->resized_devices);
+	if (list_empty(&device->post_commit_list))
+		list_add_tail(&device->post_commit_list,
+			      &trans->transaction->dev_update_list);
 
 	WARN_ON(diff > old_total);
 	btrfs_set_super_total_bytes(super_copy,
@@ -5214,9 +5211,14 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	if (ret)
 		goto error_del_extent;
 
-	for (i = 0; i < map->num_stripes; i++)
-		btrfs_device_set_bytes_used(map->stripes[i].dev,
-				map->stripes[i].dev->bytes_used + stripe_size);
+	for (i = 0; i < map->num_stripes; i++) {
+		struct btrfs_device *dev = map->stripes[i].dev;
+
+		btrfs_device_set_bytes_used(dev, dev->bytes_used + stripe_size);
+		if (list_empty(&dev->post_commit_list))
+			list_add_tail(&dev->post_commit_list,
+				      &trans->transaction->dev_update_list);
+	}
 
 	atomic64_sub(stripe_size * map->num_stripes, &info->free_chunk_space);
 
@@ -7579,51 +7581,34 @@ void btrfs_scratch_superblocks(struct block_device *bdev, const char *device_pat
 }
 
 /*
- * Update the size of all devices, which is used for writing out the
- * super blocks.
+ * Update the size and bytes used for each device where it changed.  This is
+ * delayed since we would otherwise get errors while writing out the
+ * superblocks.
+ *
+ * Must be invoked during transaction commit.
  */
-void btrfs_update_commit_device_size(struct btrfs_fs_info *fs_info)
+void btrfs_commit_device_sizes(struct btrfs_transaction *trans)
 {
-	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	struct btrfs_device *curr, *next;
 
-	if (list_empty(&fs_devices->resized_devices))
-		return;
-
-	mutex_lock(&fs_devices->device_list_mutex);
-	mutex_lock(&fs_info->chunk_mutex);
-	list_for_each_entry_safe(curr, next, &fs_devices->resized_devices,
-				 resized_list) {
-		list_del_init(&curr->resized_list);
-		curr->commit_total_bytes = curr->disk_total_bytes;
-	}
-	mutex_unlock(&fs_info->chunk_mutex);
-	mutex_unlock(&fs_devices->device_list_mutex);
-}
-
-/* Must be invoked during the transaction commit */
-void btrfs_update_commit_device_bytes_used(struct btrfs_transaction *trans)
-{
-	struct btrfs_fs_info *fs_info = trans->fs_info;
-	struct extent_map *em;
-	struct map_lookup *map;
-	struct btrfs_device *dev;
-	int i;
+	ASSERT(trans->state == TRANS_STATE_COMMIT_DOING);
 
-	if (list_empty(&trans->pending_chunks))
+	if (list_empty(&trans->dev_update_list))
 		return;
 
-	/* In order to kick the device replace finish process */
-	mutex_lock(&fs_info->chunk_mutex);
-	list_for_each_entry(em, &trans->pending_chunks, list) {
-		map = em->map_lookup;
-
-		for (i = 0; i < map->num_stripes; i++) {
-			dev = map->stripes[i].dev;
-			dev->commit_bytes_used = dev->bytes_used;
-		}
+	/*
+	 * We don't need the device_list_mutex here.  This list is owned by the
+	 * transaction and the transaction must complete before the device is
+	 * released.
+	 */
+	mutex_lock(&trans->fs_info->chunk_mutex);
+	list_for_each_entry_safe(curr, next, &trans->dev_update_list,
+				 post_commit_list) {
+		list_del_init(&curr->post_commit_list);
+		curr->commit_total_bytes = curr->disk_total_bytes;
+		curr->commit_bytes_used = curr->bytes_used;
 	}
-	mutex_unlock(&fs_info->chunk_mutex);
+	mutex_unlock(&trans->fs_info->chunk_mutex);
 }
 
 void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info)