@@ -17,6 +17,7 @@
*/
#include <linux/vmalloc.h>
+#include <linux/rbtree.h>
#include "ctree.h"
#include "disk-io.h"
#include "backref.h"
@@ -34,6 +35,266 @@ struct extent_inode_elem {
struct extent_inode_elem *next;
};
+/*
+ * ref_root is used as the root of the ref tree that hold a collection
+ * of unique references.
+ */
+struct ref_root {
+ struct rb_root rb_root;
+
+ /*
+ * The unique_refs represents the number of ref_nodes with a positive
+ * count stored in the tree. Even if a ref_node(the count is greater
+ * than one) is added, the unique_refs will only increase one.
+ */
+ unsigned int unique_refs;
+};
+
+/* ref_node is used to store a unique reference to the ref tree. */
+struct ref_node {
+ struct rb_node rb_node;
+
+ /* For NORMAL_REF, otherwise all these fields should be set to 0 */
+ u64 root_id;
+ u64 object_id;
+ u64 offset;
+
+ /* For SHARED_REF, otherwise parent field should be set to 0 */
+ u64 parent;
+
+ /* Ref to the ref_mod of btrfs_delayed_ref_node(delayed-ref.h) */
+ int ref_mod;
+};
+
+/* Dynamically allocate and initialize a ref_root */
+static struct ref_root *ref_root_alloc(void)
+{
+ struct ref_root *ref_tree;
+
+ ref_tree = kmalloc(sizeof(*ref_tree), GFP_NOFS);
+ if (!ref_tree)
+ return NULL;
+
+ ref_tree->rb_root = RB_ROOT;
+ ref_tree->unique_refs = 0;
+
+ return ref_tree;
+}
+
+/* Free all nodes in the ref tree, and reinit ref_root */
+static void ref_root_fini(struct ref_root *ref_tree)
+{
+ struct ref_node *node;
+ struct rb_node *next;
+
+ while ((next = rb_first(&ref_tree->rb_root)) != NULL) {
+ node = rb_entry(next, struct ref_node, rb_node);
+ rb_erase(next, &ref_tree->rb_root);
+ kfree(node);
+ }
+
+ ref_tree->rb_root = RB_ROOT;
+ ref_tree->unique_refs = 0;
+}
+
+/* Free dynamically allocated ref_root */
+static void ref_root_free(struct ref_root *ref_tree)
+{
+ if (!ref_tree)
+ return;
+
+ ref_root_fini(ref_tree);
+ kfree(ref_tree);
+}
+
+/*
+ * Compare ref_node with (root_id, object_id, offset, parent)
+ *
+ * The function compares the two ref_node a and b. It returns an integer less
+ * than, equal to, or greater than zero , respectively, to be less than, to
+ * equal, or be greater than b.
+ */
+static int ref_node_cmp(struct ref_node *a, struct ref_node *b)
+{
+ if (a->root_id < b->root_id)
+ return -1;
+ else if (a->root_id > b->root_id)
+ return 1;
+
+ if (a->object_id < b->object_id)
+ return -1;
+ else if (a->object_id > b->object_id)
+ return 1;
+
+ if (a->offset < b->offset)
+ return -1;
+ else if (a->offset > b->offset)
+ return 1;
+
+ if (a->parent < b->parent)
+ return -1;
+ else if (a->parent > b->parent)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Search ref_node with (root_id, object_id, offset, parent) in the tree
+ *
+ * if found, the pointer of the ref_node will be returned;
+ * if not found, NULL will be returned and pos will point to the rb_node for
+ * insert, pos_parent will point to pos'parent for insert;
+*/
+static struct ref_node *__ref_tree_search(struct ref_root *ref_tree,
+ struct rb_node ***pos,
+ struct rb_node **pos_parent,
+ u64 root_id, u64 object_id,
+ u64 offset, u64 parent)
+{
+ struct ref_node *cur = NULL;
+ struct ref_node entry;
+ int ret;
+
+ entry.root_id = root_id;
+ entry.object_id = object_id;
+ entry.offset = offset;
+ entry.parent = parent;
+
+ *pos = &ref_tree->rb_root.rb_node;
+
+ while (**pos) {
+ *pos_parent = **pos;
+ cur = rb_entry(*pos_parent, struct ref_node, rb_node);
+
+ ret = ref_node_cmp(cur, &entry);
+ if (ret > 0)
+ *pos = &(**pos)->rb_left;
+ else if (ret < 0)
+ *pos = &(**pos)->rb_right;
+ else
+ return cur;
+ }
+
+ return NULL;
+}
+
+/*
+ * Insert a ref_node to the ref tree
+ * @pos used for specifiy the position to insert
+ * @pos_parent for specifiy pos's parent
+ *
+ * success, return 0;
+ * ref_node already exists, return -EEXIST;
+*/
+static int ref_tree_insert(struct ref_root *ref_tree, struct rb_node **pos,
+ struct rb_node *pos_parent, struct ref_node *ins)
+{
+ struct rb_node **p = NULL;
+ struct rb_node *parent = NULL;
+ struct ref_node *cur = NULL;
+
+ if (!pos) {
+ cur = __ref_tree_search(ref_tree, &p, &parent, ins->root_id,
+ ins->object_id, ins->offset,
+ ins->parent);
+ if (cur)
+ return -EEXIST;
+ } else {
+ p = pos;
+ parent = pos_parent;
+ }
+
+ rb_link_node(&ins->rb_node, parent, p);
+ rb_insert_color(&ins->rb_node, &ref_tree->rb_root);
+
+ return 0;
+}
+
+/* Erase and free ref_node, caller should update ref_root->unique_refs */
+static void ref_tree_remove(struct ref_root *ref_tree, struct ref_node *node)
+{
+ rb_erase(&node->rb_node, &ref_tree->rb_root);
+ kfree(node);
+}
+
+/*
+ * Update ref_root->unique_refs
+ *
+ * Call __ref_tree_search
+ * 1. if ref_node doesn't exist, ref_tree_insert this node, and update
+ * ref_root->unique_refs:
+ * if ref_node->ref_mod > 0, ref_root->unique_refs++;
+ * if ref_node->ref_mod < 0, do noting;
+ *
+ * 2. if ref_node is found, then get origin ref_node->ref_mod, and update
+ * ref_node->ref_mod.
+ * if ref_node->ref_mod is equal to 0,then call ref_tree_remove
+ *
+ * according to origin_mod and new_mod, update ref_root->items
+ * +----------------+--------------+-------------+
+ * | |new_count <= 0|new_count > 0|
+ * +----------------+--------------+-------------+
+ * |origin_count < 0| 0 | 1 |
+ * +----------------+--------------+-------------+
+ * |origin_count > 0| -1 | 0 |
+ * +----------------+--------------+-------------+
+ *
+ * In case of allocation failure, -ENOMEM is returned and the ref_tree stays
+ * unaltered.
+ * Success, return 0
+ */
+static int ref_tree_add(struct ref_root *ref_tree, u64 root_id, u64 object_id,
+ u64 offset, u64 parent, int count)
+{
+ struct ref_node *node = NULL;
+ struct rb_node **pos = NULL;
+ struct rb_node *pos_parent = NULL;
+ int origin_count;
+ int ret;
+
+ if (!count)
+ return 0;
+
+ node = __ref_tree_search(ref_tree, &pos, &pos_parent, root_id,
+ object_id, offset, parent);
+ if (node == NULL) {
+ node = kmalloc(sizeof(*node), GFP_NOFS);
+ if (!node)
+ return -ENOMEM;
+
+ node->root_id = root_id;
+ node->object_id = object_id;
+ node->offset = offset;
+ node->parent = parent;
+ node->ref_mod = count;
+
+ ret = ref_tree_insert(ref_tree, pos, pos_parent, node);
+ ASSERT(!ret);
+ if (ret) {
+ kfree(node);
+ return ret;
+ }
+
+ ref_tree->unique_refs += node->ref_mod > 0 ? 1 : 0;
+
+ return 0;
+ }
+
+ origin_count = node->ref_mod;
+ node->ref_mod += count;
+
+ if (node->ref_mod > 0)
+ ref_tree->unique_refs += origin_count > 0 ? 0 : 1;
+ else if (node->ref_mod <= 0)
+ ref_tree->unique_refs += origin_count > 0 ? -1 : 0;
+
+ if (!node->ref_mod)
+ ref_tree_remove(ref_tree, node);
+
+ return 0;
+}
+
static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
struct btrfs_file_extent_item *fi,
u64 extent_item_pos,
@@ -703,6 +964,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
static int __add_inline_refs(struct btrfs_fs_info *fs_info,
struct btrfs_path *path, u64 bytenr,
int *info_level, struct list_head *prefs,
+ struct ref_root *ref_tree,
u64 *total_refs, u64 inum)
{
int ret = 0;
@@ -770,6 +1032,13 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
count = btrfs_shared_data_ref_count(leaf, sdref);
ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
bytenr, count, GFP_NOFS);
+ if (ref_tree) {
+ if (!ret)
+ ret = ref_tree_add(ref_tree, 0, 0, 0,
+ bytenr, count);
+ if (!ret && ref_tree->unique_refs > 1)
+ ret = BACKREF_FOUND_SHARED;
+ }
break;
}
case BTRFS_TREE_BLOCK_REF_KEY:
@@ -797,6 +1066,15 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
root = btrfs_extent_data_ref_root(leaf, dref);
ret = __add_prelim_ref(prefs, root, &key, 0, 0,
bytenr, count, GFP_NOFS);
+ if (ref_tree) {
+ if (!ret)
+ ret = ref_tree_add(ref_tree, root,
+ key.objectid,
+ key.offset, 0,
+ count);
+ if (!ret && ref_tree->unique_refs > 1)
+ ret = BACKREF_FOUND_SHARED;
+ }
break;
}
default:
@@ -815,7 +1093,8 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
*/
static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
struct btrfs_path *path, u64 bytenr,
- int info_level, struct list_head *prefs, u64 inum)
+ int info_level, struct list_head *prefs,
+ struct ref_root *ref_tree, u64 inum)
{
struct btrfs_root *extent_root = fs_info->extent_root;
int ret;
@@ -858,6 +1137,13 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
count = btrfs_shared_data_ref_count(leaf, sdref);
ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
bytenr, count, GFP_NOFS);
+ if (ref_tree) {
+ if (!ret)
+ ret = ref_tree_add(ref_tree, 0, 0, 0,
+ bytenr, count);
+ if (!ret && ref_tree->unique_refs > 1)
+ ret = BACKREF_FOUND_SHARED;
+ }
break;
}
case BTRFS_TREE_BLOCK_REF_KEY:
@@ -886,6 +1172,15 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
root = btrfs_extent_data_ref_root(leaf, dref);
ret = __add_prelim_ref(prefs, root, &key, 0, 0,
bytenr, count, GFP_NOFS);
+ if (ref_tree) {
+ if (!ret)
+ ret = ref_tree_add(ref_tree, root,
+ key.objectid,
+ key.offset, 0,
+ count);
+ if (!ret && ref_tree->unique_refs > 1)
+ ret = BACKREF_FOUND_SHARED;
+ }
break;
}
default:
@@ -912,13 +1207,16 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
* commit root.
* The special case is for qgroup to search roots in commit_transaction().
*
+ * If check_shared is set to 1, any extent has more than one ref item, will
+ * be returned BACKREF_FOUND_SHARED immediately.
+ *
* 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)
+ u64 root_objectid, u64 inum, int check_shared)
{
struct btrfs_key key;
struct btrfs_path *path;
@@ -930,6 +1228,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
struct list_head prefs;
struct __prelim_ref *ref;
struct extent_inode_elem *eie = NULL;
+ struct ref_root *ref_tree = NULL;
u64 total_refs = 0;
INIT_LIST_HEAD(&prefs);
@@ -961,6 +1260,18 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
again:
head = NULL;
+ if (check_shared) {
+ if (!ref_tree) {
+ ref_tree = ref_root_alloc();
+ if (!ref_tree) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ } else {
+ ref_root_fini(ref_tree);
+ }
+ }
+
ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
if (ret < 0)
goto out;
@@ -1005,6 +1316,36 @@ again:
} else {
spin_unlock(&delayed_refs->lock);
}
+
+ if (check_shared && !list_empty(&prefs_delayed)) {
+ /*
+ * Add all delay_ref to the ref_tree and check if there
+ * are multiple ref items added.
+ */
+ list_for_each_entry(ref, &prefs_delayed, list) {
+ if (ref->key_for_search.type) {
+ ret = ref_tree_add(ref_tree,
+ ref->root_id,
+ ref->key_for_search.objectid,
+ ref->key_for_search.offset,
+ 0, ref->count);
+ if (ret)
+ goto out;
+ } else {
+ ret = ref_tree_add(ref_tree, 0, 0, 0,
+ ref->parent, ref->count);
+ if (ret)
+ goto out;
+ }
+
+ }
+
+ if (ref_tree->unique_refs > 1) {
+ ret = BACKREF_FOUND_SHARED;
+ goto out;
+ }
+
+ }
}
if (path->slots[0]) {
@@ -1020,11 +1361,13 @@ again:
key.type == BTRFS_METADATA_ITEM_KEY)) {
ret = __add_inline_refs(fs_info, path, bytenr,
&info_level, &prefs,
- &total_refs, inum);
+ ref_tree, &total_refs,
+ inum);
if (ret)
goto out;
ret = __add_keyed_refs(fs_info, path, bytenr,
- info_level, &prefs, inum);
+ info_level, &prefs,
+ ref_tree, inum);
if (ret)
goto out;
}
@@ -1109,6 +1452,7 @@ again:
out:
btrfs_free_path(path);
+ ref_root_free(ref_tree);
while (!list_empty(&prefs)) {
ref = list_first_entry(&prefs, struct __prelim_ref, list);
list_del(&ref->list);
@@ -1162,8 +1506,8 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
if (!*leafs)
return -ENOMEM;
- ret = find_parent_nodes(trans, fs_info, bytenr,
- time_seq, *leafs, NULL, extent_item_pos, 0, 0);
+ ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
+ *leafs, NULL, extent_item_pos, 0, 0, 0);
if (ret < 0 && ret != -ENOENT) {
free_leaf_list(*leafs);
return ret;
@@ -1205,8 +1549,8 @@ static int __btrfs_find_all_roots(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);
+ ret = find_parent_nodes(trans, fs_info, bytenr, time_seq,
+ tmp, *roots, NULL, 0, 0, 0);
if (ret < 0 && ret != -ENOENT) {
ulist_free(tmp);
ulist_free(*roots);
@@ -1276,7 +1620,7 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
ULIST_ITER_INIT(&uiter);
while (1) {
ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
- roots, NULL, root_objectid, inum);
+ roots, NULL, root_objectid, inum, 1);
if (ret == BACKREF_FOUND_SHARED) {
/* this is the only condition under which we return 1 */
ret = 1;
@@ -20,6 +20,7 @@
#include "locking.h"
#include "rcu-string.h"
#include "backref.h"
+#include "transaction.h"
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
@@ -4498,21 +4499,36 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
flags |= (FIEMAP_EXTENT_DELALLOC |
FIEMAP_EXTENT_UNKNOWN);
} else if (fieinfo->fi_extents_max) {
+ struct btrfs_trans_handle *trans;
+
u64 bytenr = em->block_start -
(em->start - em->orig_start);
disko = em->block_start + offset_in_extent;
/*
+ * We need a trans handle to get delayed refs
+ */
+ trans = btrfs_join_transaction(root);
+ /*
+ * It's OK if we can't start a trans
+ * we can still check from commit_root
+ */
+ if (IS_ERR(trans))
+ trans = NULL;
+
+ /*
* As btrfs supports shared space, this information
* can be exported to userspace tools via
* flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0
* then we're just getting a count and we can skip the
* lookup stuff.
*/
- ret = btrfs_check_shared(NULL, root->fs_info,
+ ret = btrfs_check_shared(trans, root->fs_info,
root->objectid,
btrfs_ino(inode), bytenr);
+ if (trans)
+ btrfs_end_transaction(trans, root);
if (ret < 0)
goto out_free;
if (ret)
Only in the case of different root_id or different object_id, check_shared identified extent as the shared. However, If a extent was referred by different offset of same file, it should also be identified as shared. In addition, check_shared's loop scale is at least n^3, so if a extent has too many references, even causes soft hang up. First, add all delayed_ref to the ref_tree and calculate the unqiue_refs, if the unique_refs is greater than one, return BACKREF_FOUND_SHARED. Then individually add the on-disk reference(inline/keyed) to the ref_tree and calculate the unique_refs of the ref_tree to check if the unique_refs is greater than one.Because once there are two references to return SHARED, so the time complexity is close to the constant. Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com> --- fs/btrfs/backref.c | 362 +++++++++++++++++++++++++++++++++++++++++++++++++-- fs/btrfs/extent_io.c | 18 ++- 2 files changed, 370 insertions(+), 10 deletions(-)