btrfs: fix check_shared for fiemap ioctl
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> Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Lu Fengqi
David Sterba
Родитель
b0de6c4c81
Коммит
afce772e87
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@ -17,6 +17,7 @@
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*/
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#include <linux/vmalloc.h>
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#include <linux/rbtree.h>
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#include "ctree.h"
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#include "disk-io.h"
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#include "backref.h"
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@ -34,6 +35,265 @@ struct extent_inode_elem {
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struct extent_inode_elem *next;
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};
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/*
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* ref_root is used as the root of the ref tree that hold a collection
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* of unique references.
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*/
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struct ref_root {
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struct rb_root rb_root;
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/*
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* The unique_refs represents the number of ref_nodes with a positive
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* count stored in the tree. Even if a ref_node (the count is greater
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* than one) is added, the unique_refs will only increase by one.
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*/
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unsigned int unique_refs;
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};
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/* ref_node is used to store a unique reference to the ref tree. */
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struct ref_node {
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struct rb_node rb_node;
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/* For NORMAL_REF, otherwise all these fields should be set to 0 */
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u64 root_id;
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u64 object_id;
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u64 offset;
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/* For SHARED_REF, otherwise parent field should be set to 0 */
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u64 parent;
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/* Ref to the ref_mod of btrfs_delayed_ref_node */
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int ref_mod;
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};
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/* Dynamically allocate and initialize a ref_root */
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static struct ref_root *ref_root_alloc(void)
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{
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struct ref_root *ref_tree;
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ref_tree = kmalloc(sizeof(*ref_tree), GFP_NOFS);
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if (!ref_tree)
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return NULL;
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ref_tree->rb_root = RB_ROOT;
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ref_tree->unique_refs = 0;
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return ref_tree;
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}
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/* Free all nodes in the ref tree, and reinit ref_root */
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static void ref_root_fini(struct ref_root *ref_tree)
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{
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struct ref_node *node;
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struct rb_node *next;
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while ((next = rb_first(&ref_tree->rb_root)) != NULL) {
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node = rb_entry(next, struct ref_node, rb_node);
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rb_erase(next, &ref_tree->rb_root);
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kfree(node);
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}
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ref_tree->rb_root = RB_ROOT;
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ref_tree->unique_refs = 0;
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}
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static void ref_root_free(struct ref_root *ref_tree)
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{
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if (!ref_tree)
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return;
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ref_root_fini(ref_tree);
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kfree(ref_tree);
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}
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/*
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* Compare ref_node with (root_id, object_id, offset, parent)
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*
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* The function compares two ref_node a and b. It returns an integer less
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* than, equal to, or greater than zero , respectively, to be less than, to
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* equal, or be greater than b.
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*/
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static int ref_node_cmp(struct ref_node *a, struct ref_node *b)
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{
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if (a->root_id < b->root_id)
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return -1;
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else if (a->root_id > b->root_id)
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return 1;
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if (a->object_id < b->object_id)
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return -1;
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else if (a->object_id > b->object_id)
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return 1;
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if (a->offset < b->offset)
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return -1;
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else if (a->offset > b->offset)
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return 1;
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if (a->parent < b->parent)
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return -1;
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else if (a->parent > b->parent)
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return 1;
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return 0;
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}
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/*
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* Search ref_node with (root_id, object_id, offset, parent) in the tree
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*
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* if found, the pointer of the ref_node will be returned;
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* if not found, NULL will be returned and pos will point to the rb_node for
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* insert, pos_parent will point to pos'parent for insert;
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*/
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static struct ref_node *__ref_tree_search(struct ref_root *ref_tree,
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struct rb_node ***pos,
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struct rb_node **pos_parent,
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u64 root_id, u64 object_id,
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u64 offset, u64 parent)
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{
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struct ref_node *cur = NULL;
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struct ref_node entry;
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int ret;
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entry.root_id = root_id;
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entry.object_id = object_id;
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entry.offset = offset;
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entry.parent = parent;
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*pos = &ref_tree->rb_root.rb_node;
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while (**pos) {
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*pos_parent = **pos;
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cur = rb_entry(*pos_parent, struct ref_node, rb_node);
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ret = ref_node_cmp(cur, &entry);
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if (ret > 0)
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*pos = &(**pos)->rb_left;
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else if (ret < 0)
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*pos = &(**pos)->rb_right;
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else
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return cur;
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}
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return NULL;
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}
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/*
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* Insert a ref_node to the ref tree
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* @pos used for specifiy the position to insert
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* @pos_parent for specifiy pos's parent
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*
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* success, return 0;
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* ref_node already exists, return -EEXIST;
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*/
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static int ref_tree_insert(struct ref_root *ref_tree, struct rb_node **pos,
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struct rb_node *pos_parent, struct ref_node *ins)
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{
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struct rb_node **p = NULL;
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struct rb_node *parent = NULL;
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struct ref_node *cur = NULL;
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if (!pos) {
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cur = __ref_tree_search(ref_tree, &p, &parent, ins->root_id,
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ins->object_id, ins->offset,
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ins->parent);
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if (cur)
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return -EEXIST;
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} else {
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p = pos;
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parent = pos_parent;
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}
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rb_link_node(&ins->rb_node, parent, p);
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rb_insert_color(&ins->rb_node, &ref_tree->rb_root);
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return 0;
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}
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/* Erase and free ref_node, caller should update ref_root->unique_refs */
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static void ref_tree_remove(struct ref_root *ref_tree, struct ref_node *node)
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{
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rb_erase(&node->rb_node, &ref_tree->rb_root);
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kfree(node);
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}
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/*
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* Update ref_root->unique_refs
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*
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* Call __ref_tree_search
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* 1. if ref_node doesn't exist, ref_tree_insert this node, and update
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* ref_root->unique_refs:
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* if ref_node->ref_mod > 0, ref_root->unique_refs++;
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* if ref_node->ref_mod < 0, do noting;
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*
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* 2. if ref_node is found, then get origin ref_node->ref_mod, and update
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* ref_node->ref_mod.
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* if ref_node->ref_mod is equal to 0,then call ref_tree_remove
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*
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* according to origin_mod and new_mod, update ref_root->items
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* +----------------+--------------+-------------+
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* | |new_count <= 0|new_count > 0|
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* +----------------+--------------+-------------+
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* |origin_count < 0| 0 | 1 |
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* +----------------+--------------+-------------+
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* |origin_count > 0| -1 | 0 |
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* +----------------+--------------+-------------+
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*
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* In case of allocation failure, -ENOMEM is returned and the ref_tree stays
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* unaltered.
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* Success, return 0
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*/
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static int ref_tree_add(struct ref_root *ref_tree, u64 root_id, u64 object_id,
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u64 offset, u64 parent, int count)
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{
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struct ref_node *node = NULL;
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struct rb_node **pos = NULL;
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struct rb_node *pos_parent = NULL;
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int origin_count;
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int ret;
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if (!count)
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return 0;
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node = __ref_tree_search(ref_tree, &pos, &pos_parent, root_id,
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object_id, offset, parent);
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if (node == NULL) {
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node = kmalloc(sizeof(*node), GFP_NOFS);
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if (!node)
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return -ENOMEM;
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node->root_id = root_id;
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node->object_id = object_id;
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node->offset = offset;
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node->parent = parent;
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node->ref_mod = count;
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ret = ref_tree_insert(ref_tree, pos, pos_parent, node);
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ASSERT(!ret);
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if (ret) {
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kfree(node);
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return ret;
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}
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ref_tree->unique_refs += node->ref_mod > 0 ? 1 : 0;
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return 0;
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}
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origin_count = node->ref_mod;
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node->ref_mod += count;
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if (node->ref_mod > 0)
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ref_tree->unique_refs += origin_count > 0 ? 0 : 1;
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else if (node->ref_mod <= 0)
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ref_tree->unique_refs += origin_count > 0 ? -1 : 0;
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if (!node->ref_mod)
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ref_tree_remove(ref_tree, node);
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return 0;
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}
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static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
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struct btrfs_file_extent_item *fi,
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u64 extent_item_pos,
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@ -700,6 +960,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
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static int __add_inline_refs(struct btrfs_fs_info *fs_info,
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struct btrfs_path *path, u64 bytenr,
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int *info_level, struct list_head *prefs,
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struct ref_root *ref_tree,
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u64 *total_refs, u64 inum)
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{
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int ret = 0;
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@ -767,6 +1028,13 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
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count = btrfs_shared_data_ref_count(leaf, sdref);
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ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
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bytenr, count, GFP_NOFS);
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if (ref_tree) {
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if (!ret)
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ret = ref_tree_add(ref_tree, 0, 0, 0,
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bytenr, count);
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if (!ret && ref_tree->unique_refs > 1)
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ret = BACKREF_FOUND_SHARED;
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}
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break;
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}
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case BTRFS_TREE_BLOCK_REF_KEY:
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@ -794,6 +1062,15 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
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root = btrfs_extent_data_ref_root(leaf, dref);
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ret = __add_prelim_ref(prefs, root, &key, 0, 0,
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bytenr, count, GFP_NOFS);
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if (ref_tree) {
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if (!ret)
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ret = ref_tree_add(ref_tree, root,
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key.objectid,
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key.offset, 0,
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count);
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if (!ret && ref_tree->unique_refs > 1)
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ret = BACKREF_FOUND_SHARED;
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}
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break;
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}
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default:
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@ -812,7 +1089,8 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
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*/
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static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
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struct btrfs_path *path, u64 bytenr,
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int info_level, struct list_head *prefs, u64 inum)
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int info_level, struct list_head *prefs,
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struct ref_root *ref_tree, u64 inum)
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{
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struct btrfs_root *extent_root = fs_info->extent_root;
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int ret;
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@ -855,6 +1133,13 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
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count = btrfs_shared_data_ref_count(leaf, sdref);
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ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
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bytenr, count, GFP_NOFS);
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if (ref_tree) {
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if (!ret)
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ret = ref_tree_add(ref_tree, 0, 0, 0,
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bytenr, count);
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if (!ret && ref_tree->unique_refs > 1)
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ret = BACKREF_FOUND_SHARED;
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}
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break;
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}
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case BTRFS_TREE_BLOCK_REF_KEY:
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@ -883,6 +1168,15 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
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root = btrfs_extent_data_ref_root(leaf, dref);
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ret = __add_prelim_ref(prefs, root, &key, 0, 0,
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bytenr, count, GFP_NOFS);
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if (ref_tree) {
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if (!ret)
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ret = ref_tree_add(ref_tree, root,
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key.objectid,
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key.offset, 0,
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count);
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if (!ret && ref_tree->unique_refs > 1)
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ret = BACKREF_FOUND_SHARED;
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}
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break;
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}
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default:
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@ -909,13 +1203,16 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
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* commit root.
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* The special case is for qgroup to search roots in commit_transaction().
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*
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* If check_shared is set to 1, any extent has more than one ref item, will
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* be returned BACKREF_FOUND_SHARED immediately.
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*
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* FIXME some caching might speed things up
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*/
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static int find_parent_nodes(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 bytenr,
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u64 time_seq, struct ulist *refs,
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struct ulist *roots, const u64 *extent_item_pos,
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u64 root_objectid, u64 inum)
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u64 root_objectid, u64 inum, int check_shared)
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{
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struct btrfs_key key;
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struct btrfs_path *path;
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@ -927,6 +1224,7 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
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struct list_head prefs;
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struct __prelim_ref *ref;
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struct extent_inode_elem *eie = NULL;
|
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struct ref_root *ref_tree = NULL;
|
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u64 total_refs = 0;
|
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INIT_LIST_HEAD(&prefs);
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|
|
@ -958,6 +1256,18 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
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again:
|
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head = NULL;
|
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|
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if (check_shared) {
|
||||
if (!ref_tree) {
|
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ref_tree = ref_root_alloc();
|
||||
if (!ref_tree) {
|
||||
ret = -ENOMEM;
|
||||
goto out;
|
||||
}
|
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} else {
|
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ref_root_fini(ref_tree);
|
||||
}
|
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}
|
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|
||||
ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
|
|
@ -1002,6 +1312,36 @@ again:
|
|||
} else {
|
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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]) {
|
||||
|
|
@ -1017,11 +1357,13 @@ 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;
|
||||
}
|
||||
|
|
@ -1106,6 +1448,7 @@ 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);
|
||||
|
|
@ -1159,8 +1502,8 @@ 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;
|
||||
|
|
@ -1202,8 +1545,8 @@ 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);
|
||||
|
|
@ -1273,7 +1616,7 @@ 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;
|
||||
|
|
@ -4487,11 +4488,24 @@ 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
|
||||
|
|
@ -4499,9 +4513,11 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
|
|||
* 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)
|
||||
|
|
|
|||
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Ссылка в новой задаче