Commit 3e024846 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: refactor variable scope in run_delalloc_nocow 



Of the 22 (!!!) local variables declared in this function only 9 have
function-wide context. Of the remaining 13, 12 are needed in the main
while loop of the function and 1 is needed in a tiny if branch, only in
case we have prealloc extent. This commit reduces the lifespan of every
variable to its bare minimum. It also renames the 'nolock' boolean to
freespace_inode to clearly indicate its purpose.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent bcacf5f3

fs/btrfs/inode.c

+28 −33
Original line number Diff line number Diff line
@@ -1301,30 +1301,18 @@ static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info, 
 */

static noinline int run_delalloc_nocow(struct inode *inode,

				       struct page *locked_page,

			      u64 start, u64 end, int *page_started, int force,

				       const u64 start, const u64 end,

				       int *page_started, int force,

				       unsigned long *nr_written)

{

	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);

	struct btrfs_root *root = BTRFS_I(inode)->root;

	struct extent_buffer *leaf;

	struct btrfs_path *path;

	struct btrfs_file_extent_item *fi;

	struct btrfs_key found_key;

	struct extent_map *em;

	u64 cow_start;

	u64 cur_offset;

	u64 extent_end;

	u64 extent_offset;

	u64 disk_bytenr;

	u64 num_bytes;

	u64 disk_num_bytes;

	u64 ram_bytes;

	int extent_type;

	u64 cow_start = (u64)-1;

	u64 cur_offset = start;

	int ret;

	int type;

	int nocow;

	int check_prev = 1;

	bool nolock;

	bool check_prev = true;

	const bool freespace_inode = btrfs_is_free_space_inode(BTRFS_I(inode));

	u64 ino = btrfs_ino(BTRFS_I(inode));



	path = btrfs_alloc_path();
@@ -1339,11 +1327,20 @@ static noinline int run_delalloc_nocow(struct inode *inode, 
		return -ENOMEM;

	}



	nolock = btrfs_is_free_space_inode(BTRFS_I(inode));



	cow_start = (u64)-1;

	cur_offset = start;

	while (1) {

		struct btrfs_key found_key;

		struct btrfs_file_extent_item *fi;

		struct extent_buffer *leaf;

		u64 extent_end;

		u64 extent_offset;

		u64 disk_bytenr = 0;

		u64 num_bytes = 0;

		u64 disk_num_bytes;

		int type;

		u64 ram_bytes;

		int extent_type;

		bool nocow = false;



		ret = btrfs_lookup_file_extent(NULL, root, path, ino,

					       cur_offset, 0);

		if (ret < 0)
@@ -1356,7 +1353,7 @@ static noinline int run_delalloc_nocow(struct inode *inode, 
			    found_key.type == BTRFS_EXTENT_DATA_KEY)

				path->slots[0]--;

		}

		check_prev = 0;

		check_prev = false;

next_slot:

		leaf = path->nodes[0];

		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
@@ -1371,9 +1368,6 @@ next_slot: 
			leaf = path->nodes[0];

		}



		nocow = 0;

		disk_bytenr = 0;

		num_bytes = 0;

		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);



		if (found_key.objectid > ino)
@@ -1420,7 +1414,7 @@ next_slot: 
			 * Do the same check as in btrfs_cross_ref_exist but

			 * without the unnecessary search.

			 */

			if (!nolock &&

			if (!freespace_inode &&

			    btrfs_file_extent_generation(leaf, fi) <=

			    btrfs_root_last_snapshot(&root->root_item))

				goto out_check;
@@ -1442,7 +1436,7 @@ next_slot: 
					goto error;

				}



				WARN_ON_ONCE(nolock);

				WARN_ON_ONCE(freespace_inode);

				goto out_check;

			}

			disk_bytenr += extent_offset;
@@ -1452,7 +1446,7 @@ next_slot: 
			 * if there are pending snapshots for this root,

			 * we fall into common COW way.

			 */

			if (!nolock && atomic_read(&root->snapshot_force_cow))

			if (!freespace_inode && atomic_read(&root->snapshot_force_cow))

				goto out_check;

			/*

			 * force cow if csum exists in the range.
@@ -1471,12 +1465,12 @@ next_slot: 
						cur_offset = cow_start;

					goto error;

				}

				WARN_ON_ONCE(nolock);

				WARN_ON_ONCE(freespace_inode);

				goto out_check;

			}

			if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr))

				goto out_check;

			nocow = 1;

			nocow = true;

		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {

			extent_end = found_key.offset +

				btrfs_file_extent_ram_bytes(leaf, fi);
@@ -1518,6 +1512,7 @@ out_check: 


		if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {

			u64 orig_start = found_key.offset - extent_offset;

			struct extent_map *em;



			em = create_io_em(inode, cur_offset, num_bytes,

					  orig_start,

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