1 files changed, 100 insertions, 65 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e92f0b0afe9e..6266a706bff7 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -60,8 +60,6 @@ struct btrfs_iget_args {
 };
 
 struct btrfs_dio_data {
-	u64 reserve;
-	loff_t length;
 	ssize_t submitted;
 	struct extent_changeset *data_reserved;
 };
@@ -1077,7 +1075,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
 	int ret = 0;
 
 	if (btrfs_is_free_space_inode(inode)) {
-		WARN_ON_ONCE(1);
 		ret = -EINVAL;
 		goto out_unlock;
 	}
@@ -4452,6 +4449,13 @@ int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
 			   dest->root_key.objectid);
 		return -EPERM;
 	}
+	if (atomic_read(&dest->nr_swapfiles)) {
+		spin_unlock(&dest->root_item_lock);
+		btrfs_warn(fs_info,
+			   "attempt to delete subvolume %llu with active swapfile",
+			   root->root_key.objectid);
+		return -EPERM;
+	}
 	root_flags = btrfs_root_flags(&dest->root_item);
 	btrfs_set_root_flags(&dest->root_item,
 			     root_flags | BTRFS_ROOT_SUBVOL_DEAD);
@@ -7763,6 +7767,11 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct extent_map *em = *map;
+	int type;
+	u64 block_start, orig_start, orig_block_len, ram_bytes;
+	bool can_nocow = false;
+	bool space_reserved = false;
+	u64 prev_len;
 	int ret = 0;
 
 	/*
@@ -7777,9 +7786,6 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
 	if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) ||
 	    ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
 	     em->block_start != EXTENT_MAP_HOLE)) {
-		int type;
-		u64 block_start, orig_start, orig_block_len, ram_bytes;
-
 		if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
 			type = BTRFS_ORDERED_PREALLOC;
 		else
@@ -7789,53 +7795,91 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map,
 
 		if (can_nocow_extent(inode, start, &len, &orig_start,
 				     &orig_block_len, &ram_bytes, false) == 1 &&
-		    btrfs_inc_nocow_writers(fs_info, block_start)) {
-			struct extent_map *em2;
+		    btrfs_inc_nocow_writers(fs_info, block_start))
+			can_nocow = true;
+	}
+
+	prev_len = len;
+	if (can_nocow) {
+		struct extent_map *em2;
 
-			em2 = btrfs_create_dio_extent(BTRFS_I(inode), start, len,
-						      orig_start, block_start,
-						      len, orig_block_len,
-						      ram_bytes, type);
+		/* We can NOCOW, so only need to reserve metadata space. */
+		ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), len);
+		if (ret < 0) {
+			/* Our caller expects us to free the input extent map. */
+			free_extent_map(em);
+			*map = NULL;
 			btrfs_dec_nocow_writers(fs_info, block_start);
-			if (type == BTRFS_ORDERED_PREALLOC) {
-				free_extent_map(em);
-				*map = em = em2;
-			}
+			goto out;
+		}
+		space_reserved = true;
 
-			if (em2 && IS_ERR(em2)) {
-				ret = PTR_ERR(em2);
-				goto out;
-			}
-			/*
-			 * For inode marked NODATACOW or extent marked PREALLOC,
-			 * use the existing or preallocated extent, so does not
-			 * need to adjust btrfs_space_info's bytes_may_use.
-			 */
-			btrfs_free_reserved_data_space_noquota(fs_info, len);
-			goto skip_cow;
+		em2 = btrfs_create_dio_extent(BTRFS_I(inode), start, len,
+					      orig_start, block_start,
+					      len, orig_block_len,
+					      ram_bytes, type);
+		btrfs_dec_nocow_writers(fs_info, block_start);
+		if (type == BTRFS_ORDERED_PREALLOC) {
+			free_extent_map(em);
+			*map = em = em2;
 		}
-	}
 
-	/* this will cow the extent */
-	free_extent_map(em);
-	*map = em = btrfs_new_extent_direct(BTRFS_I(inode), start, len);
-	if (IS_ERR(em)) {
-		ret = PTR_ERR(em);
-		goto out;
+		if (IS_ERR(em2)) {
+			ret = PTR_ERR(em2);
+			goto out;
+		}
+	} else {
+		/* Our caller expects us to free the input extent map. */
+		free_extent_map(em);
+		*map = NULL;
+
+		/* We have to COW, so need to reserve metadata and data space. */
+		ret = btrfs_delalloc_reserve_space(BTRFS_I(inode),
+						   &dio_data->data_reserved,
+						   start, len);
+		if (ret < 0)
+			goto out;
+		space_reserved = true;
+
+		em = btrfs_new_extent_direct(BTRFS_I(inode), start, len);
+		if (IS_ERR(em)) {
+			ret = PTR_ERR(em);
+			goto out;
+		}
+		*map = em;
+		len = min(len, em->len - (start - em->start));
+		if (len < prev_len)
+			btrfs_delalloc_release_space(BTRFS_I(inode),
+						     dio_data->data_reserved,
+						     start + len, prev_len - len,
+						     true);
 	}
 
-	len = min(len, em->len - (start - em->start));
+	/*
+	 * We have created our ordered extent, so we can now release our reservation
+	 * for an outstanding extent.
+	 */
+	btrfs_delalloc_release_extents(BTRFS_I(inode), prev_len);
 
-skip_cow:
 	/*
 	 * Need to update the i_size under the extent lock so buffered
 	 * readers will get the updated i_size when we unlock.
 	 */
 	if (start + len > i_size_read(inode))
 		i_size_write(inode, start + len);
-
-	dio_data->reserve -= len;
 out:
+	if (ret && space_reserved) {
+		btrfs_delalloc_release_extents(BTRFS_I(inode), len);
+		if (can_nocow) {
+			btrfs_delalloc_release_metadata(BTRFS_I(inode), len, true);
+		} else {
+			btrfs_delalloc_release_space(BTRFS_I(inode),
+						     dio_data->data_reserved,
+						     start, len, true);
+			extent_changeset_free(dio_data->data_reserved);
+			dio_data->data_reserved = NULL;
+		}
+	}
 	return ret;
 }
 
@@ -7877,18 +7921,6 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
 	if (!dio_data)
 		return -ENOMEM;
 
-	dio_data->length = length;
-	if (write) {
-		dio_data->reserve = round_up(length, fs_info->sectorsize);
-		ret = btrfs_delalloc_reserve_space(BTRFS_I(inode),
-				&dio_data->data_reserved,
-				start, dio_data->reserve);
-		if (ret) {
-			extent_changeset_free(dio_data->data_reserved);
-			kfree(dio_data);
-			return ret;
-		}
-	}
 	iomap->private = dio_data;
 
 
@@ -7981,14 +8013,8 @@ unlock_err:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
 			     &cached_state);
 err:
-	if (dio_data) {
-		btrfs_delalloc_release_space(BTRFS_I(inode),
-				dio_data->data_reserved, start,
-				dio_data->reserve, true);
-		btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->reserve);
-		extent_changeset_free(dio_data->data_reserved);
-		kfree(dio_data);
-	}
+	kfree(dio_data);
+
 	return ret;
 }
 
@@ -8018,14 +8044,8 @@ static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 		ret = -ENOTBLK;
 	}
 
-	if (write) {
-		if (dio_data->reserve)
-			btrfs_delalloc_release_space(BTRFS_I(inode),
-					dio_data->data_reserved, pos,
-					dio_data->reserve, true);
-		btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->length);
+	if (write)
 		extent_changeset_free(dio_data->data_reserved);
-	}
 out:
 	kfree(dio_data);
 	iomap->private = NULL;
@@ -10707,8 +10727,23 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 	 * set. We use this counter to prevent snapshots. We must increment it
 	 * before walking the extents because we don't want a concurrent
 	 * snapshot to run after we've already checked the extents.
+	 *
+	 * It is possible that subvolume is marked for deletion but still not
+	 * removed yet. To prevent this race, we check the root status before
+	 * activating the swapfile.
 	 */
+	spin_lock(&root->root_item_lock);
+	if (btrfs_root_dead(root)) {
+		spin_unlock(&root->root_item_lock);
+
+		btrfs_exclop_finish(fs_info);
+		btrfs_warn(fs_info,
+		"cannot activate swapfile because subvolume %llu is being deleted",
+			root->root_key.objectid);
+		return -EPERM;
+	}
 	atomic_inc(&root->nr_swapfiles);
+	spin_unlock(&root->root_item_lock);
 
 	isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize);