Commit 1baea6f1 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: reuse roots ulist on each leaf iteration for iterate_extent_inodes() 



At iterate_extent_inodes() we collect a ulist of leaves for a given extent
with a call to btrfs_find_all_leafs() and then we enter a loop where we
iterate over all the collected leaves. Each iteration of that loop does a
call to btrfs_find_all_roots_safe(), to determine all roots from which a
leaf is accessible, and that results in allocating and releasing a ulist
to store the root IDs.

Instead of allocating and releasing the roots ulist on every iteration,
allocate a ulist before entering the loop and keep using it on each
iteration, reinitializing the ulist at the end of each iteration.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent a2c8d27e

fs/btrfs/backref.c

+31 −15
Original line number Diff line number Diff line
@@ -1674,33 +1674,37 @@ int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx) 
 * the current while iterating. The process stops when we reach the end of the

 * list.

 *

 * Found roots are added to @ctx->roots, which is allocated by this function and

 * @ctx->roots should be NULL when calling this function. This function also

 * requires @ctx->refs to be NULL, as it uses it for allocating a ulist to do

 * temporary work, and frees it before returning.

 * Found roots are added to @ctx->roots, which is allocated by this function if

 * it points to NULL, in which case the caller is responsible for freeing it

 * after it's not needed anymore.

 * This function requires @ctx->refs to be NULL, as it uses it for allocating a

 * ulist to do temporary work, and frees it before returning.

 *

 * Returns 0 on success, < 0 on error. On error @ctx->roots is always NULL.

 * Returns 0 on success, < 0 on error.

 */

static int btrfs_find_all_roots_safe(struct btrfs_backref_walk_ctx *ctx)

{

	const u64 orig_bytenr = ctx->bytenr;

	const bool orig_ignore_extent_item_pos = ctx->ignore_extent_item_pos;

	bool roots_ulist_allocated = false;

	struct ulist_iterator uiter;

	int ret = 0;



	ASSERT(ctx->refs == NULL);

	ASSERT(ctx->roots == NULL);



	ctx->refs = ulist_alloc(GFP_NOFS);

	if (!ctx->refs)

		return -ENOMEM;



	if (!ctx->roots) {

		ctx->roots = ulist_alloc(GFP_NOFS);

		if (!ctx->roots) {

			ulist_free(ctx->refs);

			ctx->refs = NULL;

			return -ENOMEM;

		}

		roots_ulist_allocated = true;

	}



	ctx->ignore_extent_item_pos = true;
@@ -1710,8 +1714,10 @@ static int btrfs_find_all_roots_safe(struct btrfs_backref_walk_ctx *ctx) 


		ret = find_parent_nodes(ctx, NULL);

		if (ret < 0 && ret != -ENOENT) {

			if (roots_ulist_allocated) {

				ulist_free(ctx->roots);

				ctx->roots = NULL;

			}

			break;

		}

		ret = 0;
@@ -2295,6 +2301,11 @@ int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx, 
		    ctx->bytenr);



	ASSERT(ctx->trans == NULL);

	ASSERT(ctx->roots == NULL);



	ctx->roots = ulist_alloc(GFP_NOFS);

	if (!ctx->roots)

		return -ENOMEM;



	if (!search_commit_root) {

		struct btrfs_trans_handle *trans;
@@ -2302,8 +2313,11 @@ int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx, 
		trans = btrfs_attach_transaction(ctx->fs_info->tree_root);

		if (IS_ERR(trans)) {

			if (PTR_ERR(trans) != -ENOENT &&

			    PTR_ERR(trans) != -EROFS)

			    PTR_ERR(trans) != -EROFS) {

				ulist_free(ctx->roots);

				ctx->roots = NULL;

				return PTR_ERR(trans);

			}

			trans = NULL;

		}

		ctx->trans = trans;
@@ -2344,8 +2358,7 @@ int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx, 
						root_node->val, ctx->bytenr,

						iterate, user_ctx);

		}

		ulist_free(ctx->roots);

		ctx->roots = NULL;

		ulist_reinit(ctx->roots);

	}



	free_leaf_list(refs);
@@ -2358,6 +2371,9 @@ int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx, 
		up_read(&ctx->fs_info->commit_root_sem);

	}



	ulist_free(ctx->roots);

	ctx->roots = NULL;



	return ret;

}