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: Jan Schmidt <list.btrfs@jan-o-sch.net>
This commit is contained in:
Jan Schmidt 2012-03-23 17:32:28 +01:00
parent 103e976616
commit 7a3ae2f8c8
4 changed files with 71 additions and 53 deletions

View file

@ -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.
@ -614,35 +620,39 @@ again:
goto out;
BUG_ON(ret == 0);
/*
* look if there are updates for this ref queued and lock the head
*/
delayed_refs = &trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
head = btrfs_find_delayed_ref_head(trans, bytenr);
if (head) {
if (!mutex_trylock(&head->mutex)) {
atomic_inc(&head->node.refs);
spin_unlock(&delayed_refs->lock);
if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) {
/*
* look if there are updates for this ref queued and lock the
* head
*/
delayed_refs = &trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
head = btrfs_find_delayed_ref_head(trans, bytenr);
if (head) {
if (!mutex_trylock(&head->mutex)) {
atomic_inc(&head->node.refs);
spin_unlock(&delayed_refs->lock);
btrfs_release_path(path);
btrfs_release_path(path);
/*
* Mutex was contended, block until it's
* released and try again
*/
mutex_lock(&head->mutex);
mutex_unlock(&head->mutex);
btrfs_put_delayed_ref(&head->node);
goto again;
}
ret = __add_delayed_refs(head, seq, &info_key, &prefs_delayed);
if (ret) {
spin_unlock(&delayed_refs->lock);
goto out;
/*
* Mutex was contended, block until it's
* released and try again
*/
mutex_lock(&head->mutex);
mutex_unlock(&head->mutex);
btrfs_put_delayed_ref(&head->node);
goto again;
}
ret = __add_delayed_refs(head, seq, &info_key,
&prefs_delayed);
if (ret) {
spin_unlock(&delayed_refs->lock);
goto out;
}
}
spin_unlock(&delayed_refs->lock);
}
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;
trans = btrfs_join_transaction(fs_info->extent_root);
if (IS_ERR(trans))
return PTR_ERR(trans);
struct btrfs_delayed_ref_root *delayed_refs = NULL;
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);
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);
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:
btrfs_put_delayed_seq(delayed_refs, &seq_elem);
btrfs_end_transaction(trans, fs_info->extent_root);
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;
}

View file

@ -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,

View file

@ -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)

View file

@ -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);
}