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btrfs: allow backref search checks for shared extents

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When called with a struct share_check, find_parent_nodes()
will detect a shared extent and immediately return with
BACKREF_SHARED_FOUND.

Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Edmund Nadolski 2017-07-12 16:20:10 -06:00 committed by David Sterba
parent 9dd14fd696
commit 3ec4d3238a
1 changed files with 115 additions and 49 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

164
fs/btrfs/backref.c
View file

@ -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 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
}
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 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
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 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
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 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
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;