Commit dce28150 authored by Goldwyn Rodrigues's avatar Goldwyn Rodrigues Committed by David Sterba
Browse files

btrfs: allocate backref_ctx on stack in find_extent_clone 



Instead of using kmalloc() to allocate backref_ctx, allocate backref_ctx
on stack. The size is reasonably small.

sizeof(backref_ctx) = 48

Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent c853a578

fs/btrfs/send.c

+11 −18
Original line number Diff line number Diff line
@@ -1307,7 +1307,7 @@ static int find_extent_clone(struct send_ctx *sctx, 
	u64 flags = 0;

	struct btrfs_file_extent_item *fi;

	struct extent_buffer *eb = path->nodes[0];

	struct backref_ctx *backref_ctx = NULL;

	struct backref_ctx backref_ctx = {0};

	struct clone_root *cur_clone_root;

	struct btrfs_key found_key;

	struct btrfs_path *tmp_path;
@@ -1322,12 +1322,6 @@ static int find_extent_clone(struct send_ctx *sctx, 
	/* We only use this path under the commit sem */

	tmp_path->need_commit_sem = 0;



	backref_ctx = kmalloc(sizeof(*backref_ctx), GFP_KERNEL);

	if (!backref_ctx) {

		ret = -ENOMEM;

		goto out;

	}



	if (data_offset >= ino_size) {

		/*

		 * There may be extents that lie behind the file's size.
@@ -1392,12 +1386,12 @@ static int find_extent_clone(struct send_ctx *sctx, 
		cur_clone_root->found_refs = 0;

	}



	backref_ctx->sctx = sctx;

	backref_ctx->found = 0;

	backref_ctx->cur_objectid = ino;

	backref_ctx->cur_offset = data_offset;

	backref_ctx->found_itself = 0;

	backref_ctx->extent_len = num_bytes;

	backref_ctx.sctx = sctx;

	backref_ctx.found = 0;

	backref_ctx.cur_objectid = ino;

	backref_ctx.cur_offset = data_offset;

	backref_ctx.found_itself = 0;

	backref_ctx.extent_len = num_bytes;



	/*

	 * The last extent of a file may be too large due to page alignment.
@@ -1405,7 +1399,7 @@ static int find_extent_clone(struct send_ctx *sctx, 
	 * __iterate_backrefs work.

	 */

	if (data_offset + num_bytes >= ino_size)

		backref_ctx->extent_len = ino_size - data_offset;

		backref_ctx.extent_len = ino_size - data_offset;



	/*

	 * Now collect all backrefs.
@@ -1416,12 +1410,12 @@ static int find_extent_clone(struct send_ctx *sctx, 
		extent_item_pos = 0;

	ret = iterate_extent_inodes(fs_info, found_key.objectid,

				    extent_item_pos, 1, __iterate_backrefs,

				    backref_ctx, false);

				    &backref_ctx, false);



	if (ret < 0)

		goto out;



	if (!backref_ctx->found_itself) {

	if (!backref_ctx.found_itself) {

		/* found a bug in backref code? */

		ret = -EIO;

		btrfs_err(fs_info,
@@ -1434,7 +1428,7 @@ static int find_extent_clone(struct send_ctx *sctx, 
		    "find_extent_clone: data_offset=%llu, ino=%llu, num_bytes=%llu, logical=%llu",

		    data_offset, ino, num_bytes, logical);



	if (!backref_ctx->found)

	if (!backref_ctx.found)

		btrfs_debug(fs_info, "no clones found");



	cur_clone_root = NULL;
@@ -1458,7 +1452,6 @@ static int find_extent_clone(struct send_ctx *sctx, 


out:

	btrfs_free_path(tmp_path);

	kfree(backref_ctx);

	return ret;

}