/*
* reads the tree block backref for an extent. tree level and root are returned
* through out_level and out_root. ptr must point to a 0 value for the first
* call and may be modified (see __get_extent_inline_ref comment).
* returns 0 if data was provided, 1 if there was no more data to provide or
* <0 on error.
*/
int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
struct btrfs_extent_item *ei, u32 item_size,
u64 *out_root, u8 *out_level)
{
int ret;
int type;
struct btrfs_tree_block_info *info;
struct btrfs_extent_inline_ref *eiref;
if (*ptr == (unsigned long)-1)
return 1;
while (1) {
ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
&eiref, &type);
if (ret < 0)
return ret;
if (type == BTRFS_TREE_BLOCK_REF_KEY ||
type == BTRFS_SHARED_BLOCK_REF_KEY)
break;
if (ret == 1)
return 1;
}
/* we can treat both ref types equally here */
info = (struct btrfs_tree_block_info *)(ei + 1);
*out_root = btrfs_extent_inline_ref_offset(eb, eiref);
*out_level = btrfs_tree_block_level(eb, info);
if (ret == 1)
*ptr = (unsigned long)-1;
return 0;
}
/*
* calls iterate() for every inode that references the extent identified by
* the given parameters. will use the path given as a parameter and return it
* released.
* when the iterator function returns a non-zero value, iteration stops.
*/
int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
u64 extent_item_objectid,
u64 extent_offset,
iterate_extent_inodes_t *iterate, void *ctx)
{
unsigned long ptr = 0;
int last;
int ret;
int type;
u64 logical;
u32 item_size;
struct btrfs_extent_inline_ref *eiref;
struct btrfs_extent_data_ref *dref;
struct extent_buffer *eb;
struct btrfs_extent_item *ei;
struct btrfs_key key;
struct list_head data_refs = LIST_HEAD_INIT(data_refs);
struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
struct __data_ref *ref_d;
struct __shared_ref *ref_s;
eb = path->nodes[0];
ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
item_size = btrfs_item_size_nr(eb, path->slots[0]);
/* first we iterate the inline refs, ... */
do {
last = __get_extent_inline_ref(&ptr, eb, ei, item_size,
&eiref, &type);
if (last == -ENOENT) {
ret = 0;
break;
}
if (last < 0) {
ret = last;
break;
}
if (type == BTRFS_EXTENT_DATA_REF_KEY) {
dref = (struct btrfs_extent_data_ref *)(&eiref->offset);
ret = __data_list_add_eb(&data_refs, eb, dref);
} else if (type == BTRFS_SHARED_DATA_REF_KEY) {
logical = btrfs_extent_inline_ref_offset(eb, eiref);
ret = __shared_list_add(&shared_refs, logical);
}
} while (!ret && !last);
/* ... then we proceed to in-tree references and ... */
while (!ret) {
++path->slots[0];
if (path->slots[0] > btrfs_header_nritems(eb)) {
ret = btrfs_next_leaf(fs_info->extent_root, path);
if (ret) {
if (ret == 1)
ret = 0; /* we're done */
break;
}
eb = path->nodes[0];
}
btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
if (key.objectid != extent_item_objectid)
break;
if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
dref = btrfs_item_ptr(eb, path->slots[0],
struct btrfs_extent_data_ref);
ret = __data_list_add_eb(&data_refs, eb, dref);
} else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
static int __iter_shared_inline_ref_inodes(struct btrfs_fs_info *fs_info,
u64 logical, u64 inum,
u64 extent_data_item_offset,
u64 extent_offset,
struct btrfs_path *path,
struct list_head *data_refs,
iterate_extent_inodes_t *iterate,
void *ctx)
{
u64 ref_root;
u32 item_size;
struct btrfs_key key;
struct extent_buffer *eb;
struct btrfs_extent_item *ei;
struct btrfs_extent_inline_ref *eiref;
struct __data_ref *ref;
int ret;
int type;
int last;
unsigned long ptr = 0;
WARN_ON(!list_empty(data_refs));
ret = extent_from_logical(fs_info, logical, path, &key);
if (ret & BTRFS_EXTENT_FLAG_DATA)
ret = -EIO;
if (ret < 0)
goto out;
eb = path->nodes[0];
ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
item_size = btrfs_item_size_nr(eb, path->slots[0]);
ret = 0;
ref_root = 0;
/*
* as done in iterate_extent_inodes, we first build a list of refs to
* iterate, then free the path and then iterate them to avoid deadlocks.
*/
do {
last = __get_extent_inline_ref(&ptr, eb, ei, item_size,
&eiref, &type);
if (last < 0) {
ret = last;
goto out;
}
if (type == BTRFS_TREE_BLOCK_REF_KEY ||
type == BTRFS_SHARED_BLOCK_REF_KEY) {
ref_root = btrfs_extent_inline_ref_offset(eb, eiref);
ret = __data_list_add(data_refs, inum,
extent_data_item_offset,
ref_root);
}
} while (!ret && !last);
btrfs_release_path(path);
if (ref_root == 0) {
printk(KERN_ERR "btrfs: failed to find tree block ref "
"for shared data backref %llu\n", logical);
WARN_ON(1);
ret = -EIO;
}
out:
while (!list_empty(data_refs)) {
ref = list_first_entry(data_refs, struct __data_ref, list);
list_del(&ref->list);
if (!ret)
ret = iterate(ref->inum, extent_offset +
ref->extent_data_item_offset,
ref->root, ctx);
kfree(ref);
}
return ret;
}
