Commit 7a3ae2f8 authored by Jan Schmidt's avatar Jan Schmidt
Browse files

Btrfs: fix regression in scrub path resolving 



In commit 4692cf58 we introduced new backref walking code for btrfs. This
assumes we're searching live roots, which requires a transaction context.
While scrubbing, however, we must not join a transaction because this could
deadlock with the commit path. Additionally, what scrub really wants to do
is resolving a logical address in the commit root it's currently checking.

This patch adds support for logical to path resolving on commit roots and
makes scrub use that.

Signed-off-by: default avatarJan Schmidt <list.btrfs@jan-o-sch.net>
parent 103e9766

fs/btrfs/backref.c

+66 −49
Original line number Diff line number Diff line
@@ -116,6 +116,7 @@ add_parent: 
 * to a logical address

 */

static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,

					int search_commit_root,

					struct __prelim_ref *ref,

					struct ulist *parents)

{
@@ -131,6 +132,7 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, 
	path = btrfs_alloc_path();

	if (!path)

		return -ENOMEM;

	path->search_commit_root = !!search_commit_root;



	root_key.objectid = ref->root_id;

	root_key.type = BTRFS_ROOT_ITEM_KEY;
@@ -188,6 +190,7 @@ out: 
 * resolve all indirect backrefs from the list

 */

static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,

				   int search_commit_root,

				   struct list_head *head)

{

	int err;
@@ -212,7 +215,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, 
			continue;

		if (ref->count == 0)

			continue;

		err = __resolve_indirect_ref(fs_info, ref, parents);

		err = __resolve_indirect_ref(fs_info, search_commit_root,

					     ref, parents);

		if (err) {

			if (ret == 0)

				ret = err;
@@ -586,6 +590,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans, 
	struct btrfs_delayed_ref_head *head;

	int info_level = 0;

	int ret;

	int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT);

	struct list_head prefs_delayed;

	struct list_head prefs;

	struct __prelim_ref *ref;
@@ -600,6 +605,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans, 
	path = btrfs_alloc_path();

	if (!path)

		return -ENOMEM;

	path->search_commit_root = !!search_commit_root;



	/*

	 * grab both a lock on the path and a lock on the delayed ref head.
@@ -614,8 +620,10 @@ again: 
		goto out;

	BUG_ON(ret == 0);



	if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {

		/*

	 * look if there are updates for this ref queued and lock the head

		 * look if there are updates for this ref queued and lock the

		 * head

		 */

		delayed_refs = &trans->transaction->delayed_refs;

		spin_lock(&delayed_refs->lock);
@@ -636,13 +644,15 @@ again: 
				btrfs_put_delayed_ref(&head->node);

				goto again;

			}

		ret = __add_delayed_refs(head, seq, &info_key, &prefs_delayed);

			ret = __add_delayed_refs(head, seq, &info_key,

						 &prefs_delayed);

			if (ret) {

				spin_unlock(&delayed_refs->lock);

				goto out;

			}

		}

		spin_unlock(&delayed_refs->lock);

	}



	if (path->slots[0]) {

		struct extent_buffer *leaf;
@@ -679,7 +689,7 @@ again: 
	if (ret)

		goto out;



	ret = __resolve_indirect_refs(fs_info, &prefs);

	ret = __resolve_indirect_refs(fs_info, search_commit_root, &prefs);

	if (ret)

		goto out;
@@ -1074,8 +1084,7 @@ int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, 
	return 0;

}



static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,

				struct btrfs_path *path, u64 logical,

static int iterate_leaf_refs(struct btrfs_fs_info *fs_info, u64 logical,

				u64 orig_extent_item_objectid,

				u64 extent_item_pos, u64 root,

				iterate_extent_inodes_t *iterate, void *ctx)
@@ -1143,35 +1152,38 @@ static int iterate_leaf_refs(struct btrfs_fs_info *fs_info, 
 * calls iterate() for every inode that references the extent identified by

 * the given parameters.

 * when the iterator function returns a non-zero value, iteration stops.

 * path is guaranteed to be in released state when iterate() is called.

 */

int iterate_extent_inodes(struct btrfs_fs_info *fs_info,

				struct btrfs_path *path,

				u64 extent_item_objectid, u64 extent_item_pos,

				int search_commit_root,

				iterate_extent_inodes_t *iterate, void *ctx)

{

	int ret;

	struct list_head data_refs = LIST_HEAD_INIT(data_refs);

	struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);

	struct btrfs_trans_handle *trans;

	struct ulist *refs;

	struct ulist *roots;

	struct ulist *refs = NULL;

	struct ulist *roots = NULL;

	struct ulist_node *ref_node = NULL;

	struct ulist_node *root_node = NULL;

	struct seq_list seq_elem;

	struct btrfs_delayed_ref_root *delayed_refs;

	struct btrfs_delayed_ref_root *delayed_refs = NULL;



	pr_debug("resolving all inodes for extent %llu\n",

			extent_item_objectid);



	if (search_commit_root) {

		trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT;

	} else {

		trans = btrfs_join_transaction(fs_info->extent_root);

		if (IS_ERR(trans))

			return PTR_ERR(trans);



	pr_debug("resolving all inodes for extent %llu\n",

			extent_item_objectid);



		delayed_refs = &trans->transaction->delayed_refs;

		spin_lock(&delayed_refs->lock);

		btrfs_get_delayed_seq(delayed_refs, &seq_elem);

		spin_unlock(&delayed_refs->lock);

	}



	ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,

				   extent_item_pos, seq_elem.seq,
@@ -1188,7 +1200,7 @@ int iterate_extent_inodes(struct btrfs_fs_info *fs_info, 
		while (!ret && (root_node = ulist_next(roots, root_node))) {

			pr_debug("root %llu references leaf %llu\n",

					root_node->val, ref_node->val);

			ret = iterate_leaf_refs(fs_info, path, ref_node->val,

			ret = iterate_leaf_refs(fs_info, ref_node->val,

						extent_item_objectid,

						extent_item_pos, root_node->val,

						iterate, ctx);
@@ -1198,8 +1210,11 @@ int iterate_extent_inodes(struct btrfs_fs_info *fs_info, 
	ulist_free(refs);

	ulist_free(roots);

out:

	if (!search_commit_root) {

		btrfs_put_delayed_seq(delayed_refs, &seq_elem);

		btrfs_end_transaction(trans, fs_info->extent_root);

	}



	return ret;

}
@@ -1210,6 +1225,7 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, 
	int ret;

	u64 extent_item_pos;

	struct btrfs_key found_key;

	int search_commit_root = path->search_commit_root;



	ret = extent_from_logical(fs_info, logical, path,

					&found_key);
@@ -1220,8 +1236,9 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, 
		return ret;



	extent_item_pos = logical - found_key.objectid;

	ret = iterate_extent_inodes(fs_info, path, found_key.objectid,

					extent_item_pos, iterate, ctx);

	ret = iterate_extent_inodes(fs_info, found_key.objectid,

					extent_item_pos, search_commit_root,

					iterate, ctx);



	return ret;

}

fs/btrfs/backref.h

+3 −2
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
#include "ioctl.h"

#include "ulist.h"



#define BTRFS_BACKREF_SEARCH_COMMIT_ROOT ((struct btrfs_trans_handle *)0)



struct inode_fs_paths {

	struct btrfs_path		*btrfs_path;

	struct btrfs_root		*fs_root;
@@ -44,9 +46,8 @@ int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, 
				u64 *out_root, u8 *out_level);



int iterate_extent_inodes(struct btrfs_fs_info *fs_info,

				struct btrfs_path *path,

				u64 extent_item_objectid,

				u64 extent_offset,

				u64 extent_offset, int search_commit_root,

				iterate_extent_inodes_t *iterate, void *ctx);



int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,

fs/btrfs/ioctl.c

+2 −2
Original line number Diff line number Diff line
@@ -3067,8 +3067,8 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root, 
		goto out;



	extent_item_pos = loi->logical - key.objectid;

	ret = iterate_extent_inodes(root->fs_info, path, key.objectid,

					extent_item_pos, build_ino_list,

	ret = iterate_extent_inodes(root->fs_info, key.objectid,

					extent_item_pos, 0, build_ino_list,

					inodes);



	if (ret < 0)

fs/btrfs/scrub.c

+2 −2
Original line number Diff line number Diff line
@@ -352,8 +352,8 @@ static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio, 
		} while (ret != 1);

	} else {

		swarn.path = path;

		iterate_extent_inodes(fs_info, path, found_key.objectid,

					extent_item_pos,

		iterate_extent_inodes(fs_info, found_key.objectid,

					extent_item_pos, 1,

					scrub_print_warning_inode, &swarn);

	}

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