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-rw-r--r--fs/btrfs/backref.c164
1 files changed, 115 insertions, 49 deletions
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 9593102bdc2c..2a983a640069 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -134,6 +134,25 @@ struct preftrees {
struct preftree indirect_missing_keys;
};
+/*
+ * Checks for a shared extent during backref search.
+ *
+ * The share_count tracks prelim_refs (direct and indirect) having a
+ * ref->count >0:
+ * - incremented when a ref->count transitions to >0
+ * - decremented when a ref->count transitions to <1
+ */
+struct share_check {
+ u64 root_objectid;
+ u64 inum;
+ int share_count;
+};
+
+static inline int extent_is_shared(struct share_check *sc)
+{
+ return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0;
+}
+
static struct kmem_cache *btrfs_prelim_ref_cache;
int __init btrfs_prelim_ref_init(void)
@@ -194,14 +213,26 @@ static int prelim_ref_compare(struct prelim_ref *ref1,
return 0;
}
+void update_share_count(struct share_check *sc, int oldcount, int newcount)
+{
+ if ((!sc) || (oldcount == 0 && newcount < 1))
+ return;
+
+ if (oldcount > 0 && newcount < 1)
+ sc->share_count--;
+ else if (oldcount < 1 && newcount > 0)
+ sc->share_count++;
+}
+
/*
* Add @newref to the @root rbtree, merging identical refs.
*
- * Callers should assumed that newref has been freed after calling.
+ * Callers should assume that newref has been freed after calling.
*/
static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
struct preftree *preftree,
- struct prelim_ref *newref)
+ struct prelim_ref *newref,
+ struct share_check *sc)
{
struct rb_root *root;
struct rb_node **p;
@@ -233,12 +264,20 @@ static void prelim_ref_insert(const struct btrfs_fs_info *fs_info,
eie->next = newref->inode_list;
trace_btrfs_prelim_ref_merge(fs_info, ref, newref,
preftree->count);
+ /*
+ * A delayed ref can have newref->count < 0.
+ * The ref->count is updated to follow any
+ * BTRFS_[ADD|DROP]_DELAYED_REF actions.
+ */
+ update_share_count(sc, ref->count,
+ ref->count + newref->count);
ref->count += newref->count;
free_pref(newref);
return;
}
}
+ update_share_count(sc, 0, newref->count);
preftree->count++;
trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
rb_link_node(&newref->rbnode, parent, p);
@@ -302,7 +341,8 @@ static void prelim_release(struct preftree *preftree)
static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
struct preftree *preftree, u64 root_id,
const struct btrfs_key *key, int level, u64 parent,
- u64 wanted_disk_byte, int count, gfp_t gfp_mask)
+ u64 wanted_disk_byte, int count,
+ struct share_check *sc, gfp_t gfp_mask)
{
struct prelim_ref *ref;
@@ -347,32 +387,33 @@ static int add_prelim_ref(const struct btrfs_fs_info *fs_info,
ref->count = count;
ref->parent = parent;
ref->wanted_disk_byte = wanted_disk_byte;
- prelim_ref_insert(fs_info, preftree, ref);
-
- return 0;
+ prelim_ref_insert(fs_info, preftree, ref, sc);
+ return extent_is_shared(sc);
}
/* direct refs use root == 0, key == NULL */
static int add_direct_ref(const struct btrfs_fs_info *fs_info,
struct preftrees *preftrees, int level, u64 parent,
- u64 wanted_disk_byte, int count, gfp_t gfp_mask)
+ u64 wanted_disk_byte, int count,
+ struct share_check *sc, gfp_t gfp_mask)
{
return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
- parent, wanted_disk_byte, count, gfp_mask);
+ parent, wanted_disk_byte, count, sc, gfp_mask);
}
/* indirect refs use parent == 0 */
static int add_indirect_ref(const struct btrfs_fs_info *fs_info,
struct preftrees *preftrees, u64 root_id,
const struct btrfs_key *key, int level,
- u64 wanted_disk_byte, int count, gfp_t gfp_mask)
+ u64 wanted_disk_byte, int count,
+ struct share_check *sc, gfp_t gfp_mask)
{
struct preftree *tree = &preftrees->indirect;
if (!key)
tree = &preftrees->indirect_missing_keys;
return add_prelim_ref(fs_info, tree, root_id, key, level, 0,
- wanted_disk_byte, count, gfp_mask);
+ wanted_disk_byte, count, sc, gfp_mask);
}
static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
@@ -575,7 +616,7 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
struct btrfs_path *path, u64 time_seq,
struct preftrees *preftrees,
const u64 *extent_item_pos, u64 total_refs,
- u64 root_objectid)
+ struct share_check *sc)
{
int err;
int ret = 0;
@@ -612,7 +653,8 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
continue;
}
- if (root_objectid && ref->root_id != root_objectid) {
+ if (sc && sc->root_objectid &&
+ ref->root_id != sc->root_objectid) {
free_pref(ref);
ret = BACKREF_FOUND_SHARED;
goto out;
@@ -625,7 +667,8 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
* and return directly.
*/
if (err == -ENOENT) {
- prelim_ref_insert(fs_info, &preftrees->direct, ref);
+ prelim_ref_insert(fs_info, &preftrees->direct, ref,
+ NULL);
continue;
} else if (err) {
free_pref(ref);
@@ -653,11 +696,15 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
memcpy(new_ref, ref, sizeof(*ref));
new_ref->parent = node->val;
new_ref->inode_list = unode_aux_to_inode_list(node);
- prelim_ref_insert(fs_info, &preftrees->direct, new_ref);
+ prelim_ref_insert(fs_info, &preftrees->direct,
+ new_ref, NULL);
}
- /* Now it's a direct ref, put it in the the direct tree */
- prelim_ref_insert(fs_info, &preftrees->direct, ref);
+ /*
+ * Now it's a direct ref, put it in the the direct tree. We must
+ * do this last because the ref could be merged/freed here.
+ */
+ prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL);
ulist_reinit(parents);
cond_resched();
@@ -702,7 +749,7 @@ static int add_missing_keys(struct btrfs_fs_info *fs_info,
btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
- prelim_ref_insert(fs_info, &preftrees->indirect, ref);
+ prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
cond_resched();
}
return 0;
@@ -715,7 +762,7 @@ static int add_missing_keys(struct btrfs_fs_info *fs_info,
static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_head *head, u64 seq,
struct preftrees *preftrees, u64 *total_refs,
- u64 inum)
+ struct share_check *sc)
{
struct btrfs_delayed_ref_node *node;
struct btrfs_delayed_extent_op *extent_op = head->extent_op;
@@ -760,7 +807,7 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
&tmp_op_key, ref->level + 1,
node->bytenr,
node->ref_mod * sgn,
- GFP_ATOMIC);
+ sc, GFP_ATOMIC);
break;
}
case BTRFS_SHARED_BLOCK_REF_KEY: {
@@ -772,7 +819,7 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
ret = add_direct_ref(fs_info, preftrees,
ref->level + 1, ref->parent,
node->bytenr, node->ref_mod * sgn,
- GFP_ATOMIC);
+ sc, GFP_ATOMIC);
break;
}
case BTRFS_EXTENT_DATA_REF_KEY: {
@@ -788,15 +835,15 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
* Found a inum that doesn't match our known inum, we
* know it's shared.
*/
- if (inum && ref->objectid != inum) {
+ if (sc && sc->inum && ref->objectid != sc->inum) {
ret = BACKREF_FOUND_SHARED;
- break;
+ goto out;
}
ret = add_indirect_ref(fs_info, preftrees, ref->root,
&key, 0, node->bytenr,
node->ref_mod * sgn,
- GFP_ATOMIC);
+ sc, GFP_ATOMIC);
break;
}
case BTRFS_SHARED_DATA_REF_KEY: {
@@ -808,26 +855,35 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
ret = add_direct_ref(fs_info, preftrees, 0,
ref->parent, node->bytenr,
node->ref_mod * sgn,
- GFP_ATOMIC);
+ sc, GFP_ATOMIC);
break;
}
default:
WARN_ON(1);
}
- if (ret)
+ /*
+ * We must ignore BACKREF_FOUND_SHARED until all delayed
+ * refs have been checked.
+ */
+ if (ret && (ret != BACKREF_FOUND_SHARED))
break;
}
+ if (!ret)
+ ret = extent_is_shared(sc);
+out:
spin_unlock(&head->lock);
return ret;
}
/*
* add all inline backrefs for bytenr to the list
+ *
+ * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
*/
static int add_inline_refs(const struct btrfs_fs_info *fs_info,
struct btrfs_path *path, u64 bytenr,
int *info_level, struct preftrees *preftrees,
- u64 *total_refs, u64 inum)
+ u64 *total_refs, struct share_check *sc)
{
int ret = 0;
int slot;
@@ -884,7 +940,7 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
case BTRFS_SHARED_BLOCK_REF_KEY:
ret = add_direct_ref(fs_info, preftrees,
*info_level + 1, offset,
- bytenr, 1, GFP_NOFS);
+ bytenr, 1, NULL, GFP_NOFS);
break;
case BTRFS_SHARED_DATA_REF_KEY: {
struct btrfs_shared_data_ref *sdref;
@@ -894,13 +950,13 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
count = btrfs_shared_data_ref_count(leaf, sdref);
ret = add_direct_ref(fs_info, preftrees, 0, offset,
- bytenr, count, GFP_NOFS);
+ bytenr, count, sc, GFP_NOFS);
break;
}
case BTRFS_TREE_BLOCK_REF_KEY:
ret = add_indirect_ref(fs_info, preftrees, offset,
NULL, *info_level + 1,
- bytenr, 1, GFP_NOFS);
+ bytenr, 1, NULL, GFP_NOFS);
break;
case BTRFS_EXTENT_DATA_REF_KEY: {
struct btrfs_extent_data_ref *dref;
@@ -914,7 +970,7 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = btrfs_extent_data_ref_offset(leaf, dref);
- if (inum && key.objectid != inum) {
+ if (sc && sc->inum && key.objectid != sc->inum) {
ret = BACKREF_FOUND_SHARED;
break;
}
@@ -923,7 +979,7 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
ret = add_indirect_ref(fs_info, preftrees, root,
&key, 0, bytenr, count,
- GFP_NOFS);
+ sc, GFP_NOFS);
break;
}
default:
@@ -939,11 +995,13 @@ static int add_inline_refs(const struct btrfs_fs_info *fs_info,
/*
* add all non-inline backrefs for bytenr to the list
+ *
+ * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED.
*/
static int add_keyed_refs(struct btrfs_fs_info *fs_info,
struct btrfs_path *path, u64 bytenr,
int info_level, struct preftrees *preftrees,
- u64 inum)
+ struct share_check *sc)
{
struct btrfs_root *extent_root = fs_info->extent_root;
int ret;
@@ -976,7 +1034,7 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
/* SHARED DIRECT METADATA backref */
ret = add_direct_ref(fs_info, preftrees,
info_level + 1, key.offset,
- bytenr, 1, GFP_NOFS);
+ bytenr, 1, NULL, GFP_NOFS);
break;
case BTRFS_SHARED_DATA_REF_KEY: {
/* SHARED DIRECT FULL backref */
@@ -988,14 +1046,14 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
count = btrfs_shared_data_ref_count(leaf, sdref);
ret = add_direct_ref(fs_info, preftrees, 0,
key.offset, bytenr, count,
- GFP_NOFS);
+ sc, GFP_NOFS);
break;
}
case BTRFS_TREE_BLOCK_REF_KEY:
/* NORMAL INDIRECT METADATA backref */
ret = add_indirect_ref(fs_info, preftrees, key.offset,
NULL, info_level + 1, bytenr,
- 1, GFP_NOFS);
+ 1, NULL, GFP_NOFS);
break;
case BTRFS_EXTENT_DATA_REF_KEY: {
/* NORMAL INDIRECT DATA backref */
@@ -1011,7 +1069,7 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = btrfs_extent_data_ref_offset(leaf, dref);
- if (inum && key.objectid != inum) {
+ if (sc && sc->inum && key.objectid != sc->inum) {
ret = BACKREF_FOUND_SHARED;
break;
}
@@ -1019,7 +1077,7 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
root = btrfs_extent_data_ref_root(leaf, dref);
ret = add_indirect_ref(fs_info, preftrees, root,
&key, 0, bytenr, count,
- GFP_NOFS);
+ sc, GFP_NOFS);
break;
}
default:
@@ -1039,20 +1097,23 @@ static int add_keyed_refs(struct btrfs_fs_info *fs_info,
* indirect refs to their parent bytenr.
* When roots are found, they're added to the roots list
*
- * NOTE: This can return values > 0
- *
* If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave
* much like trans == NULL case, the difference only lies in it will not
* commit root.
* The special case is for qgroup to search roots in commit_transaction().
*
+ * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a
+ * shared extent is detected.
+ *
+ * Otherwise this returns 0 for success and <0 for an error.
+ *
* FIXME some caching might speed things up
*/
static int find_parent_nodes(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info, u64 bytenr,
u64 time_seq, struct ulist *refs,
struct ulist *roots, const u64 *extent_item_pos,
- u64 root_objectid, u64 inum)
+ struct share_check *sc)
{
struct btrfs_key key;
struct btrfs_path *path;
@@ -1133,7 +1194,7 @@ again:
}
spin_unlock(&delayed_refs->lock);
ret = add_delayed_refs(fs_info, head, time_seq,
- &preftrees, &total_refs, inum);
+ &preftrees, &total_refs, sc);
mutex_unlock(&head->mutex);
if (ret)
goto out;
@@ -1155,11 +1216,11 @@ again:
key.type == BTRFS_METADATA_ITEM_KEY)) {
ret = add_inline_refs(fs_info, path, bytenr,
&info_level, &preftrees,
- &total_refs, inum);
+ &total_refs, sc);
if (ret)
goto out;
ret = add_keyed_refs(fs_info, path, bytenr, info_level,
- &preftrees, inum);
+ &preftrees, sc);
if (ret)
goto out;
}
@@ -1174,8 +1235,7 @@ again:
WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root));
ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees,
- extent_item_pos, total_refs,
- root_objectid);
+ extent_item_pos, total_refs, sc);
if (ret)
goto out;
@@ -1194,7 +1254,8 @@ again:
node = rb_next(&ref->rbnode);
WARN_ON(ref->count < 0);
if (roots && ref->count && ref->root_id && ref->parent == 0) {
- if (root_objectid && ref->root_id != root_objectid) {
+ if (sc && sc->root_objectid &&
+ ref->root_id != sc->root_objectid) {
ret = BACKREF_FOUND_SHARED;
goto out;
}
@@ -1298,7 +1359,7 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
return -ENOMEM;
ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
- *leafs, NULL, extent_item_pos, 0, 0);
+ *leafs, NULL, extent_item_pos, NULL);
if (ret < 0 && ret != -ENOENT) {
free_leaf_list(*leafs);
return ret;
@@ -1341,7 +1402,7 @@ static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans,
ULIST_ITER_INIT(&uiter);
while (1) {
ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
- tmp, *roots, NULL, 0, 0);
+ tmp, *roots, NULL, NULL);
if (ret < 0 && ret != -ENOENT) {
ulist_free(tmp);
ulist_free(*roots);
@@ -1397,6 +1458,11 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
struct ulist_node *node;
struct seq_list elem = SEQ_LIST_INIT(elem);
int ret = 0;
+ struct share_check shared = {
+ .root_objectid = root->objectid,
+ .inum = inum,
+ .share_count = 0,
+ };
tmp = ulist_alloc(GFP_NOFS);
roots = ulist_alloc(GFP_NOFS);
@@ -1417,7 +1483,7 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
ULIST_ITER_INIT(&uiter);
while (1) {
ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
- roots, NULL, root->objectid, inum);
+ roots, NULL, &shared);
if (ret == BACKREF_FOUND_SHARED) {
/* this is the only condition under which we return 1 */
ret = 1;
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-25 10:40:33 +0300