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linux/fs/btrfs/backref.c
Qu Wenruo 789d6a3a87 btrfs: concentrate all tree block parentness check parameters into one structure 
There are several different tree block parentness check parameters used
across several helpers:

- level
  Mandatory

- transid
  Under most cases it's mandatory, but there are several backref cases
  which skips this check.

- owner_root
- first_key
  Utilized by most top-down tree search routine. Otherwise can be
  skipped.

Those four members are not always mandatory checks, and some of them are
the same u64, which means if some arguments got swapped compiler will
not catch it.

Furthermore if we're going to further expand the parentness check, we
need to modify quite some helpers just to add one more parameter.

This patch will concentrate all these members into a structure called
btrfs_tree_parent_check, and pass that structure for the following
helpers:

- btrfs_read_extent_buffer()
- read_tree_block()

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05 18:00:56 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2011 STRATO. All rights reserved.
*/
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <trace/events/btrfs.h>
#include "ctree.h"
#include "disk-io.h"
#include "backref.h"
#include "ulist.h"
#include "transaction.h"
#include "delayed-ref.h"
#include "locking.h"
#include "misc.h"
#include "tree-mod-log.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
#include "relocation.h"
/* Just arbitrary numbers so we can be sure one of these happened. */
#define BACKREF_FOUND_SHARED 6
#define BACKREF_FOUND_NOT_SHARED 7
struct extent_inode_elem {
u64 inum;
u64 offset;
u64 num_bytes;
struct extent_inode_elem *next;
};
static int check_extent_in_eb(struct btrfs_backref_walk_ctx *ctx,
const struct btrfs_key *key,
const struct extent_buffer *eb,
const struct btrfs_file_extent_item *fi,
struct extent_inode_elem **eie)
{
const u64 data_len = btrfs_file_extent_num_bytes(eb, fi);
u64 offset = key->offset;
struct extent_inode_elem *e;
const u64 *root_ids;
int root_count;
bool cached;
if (!btrfs_file_extent_compression(eb, fi) &&
!btrfs_file_extent_encryption(eb, fi) &&
!btrfs_file_extent_other_encoding(eb, fi)) {
u64 data_offset;
data_offset = btrfs_file_extent_offset(eb, fi);
if (ctx->extent_item_pos < data_offset ||
ctx->extent_item_pos >= data_offset + data_len)
return 1;
offset += ctx->extent_item_pos - data_offset;
}
if (!ctx->indirect_ref_iterator || !ctx->cache_lookup)
goto add_inode_elem;
cached = ctx->cache_lookup(eb->start, ctx->user_ctx, &root_ids,
&root_count);
if (!cached)
goto add_inode_elem;
for (int i = 0; i < root_count; i++) {
int ret;
ret = ctx->indirect_ref_iterator(key->objectid, offset,
data_len, root_ids[i],
ctx->user_ctx);
if (ret)
return ret;
}
add_inode_elem:
e = kmalloc(sizeof(*e), GFP_NOFS);
if (!e)
return -ENOMEM;
e->next = *eie;
e->inum = key->objectid;
e->offset = offset;
e->num_bytes = data_len;
*eie = e;
return 0;
}
static void free_inode_elem_list(struct extent_inode_elem *eie)
{
struct extent_inode_elem *eie_next;
for (; eie; eie = eie_next) {
eie_next = eie->next;
kfree(eie);
}
}
static int find_extent_in_eb(struct btrfs_backref_walk_ctx *ctx,
const struct extent_buffer *eb,
struct extent_inode_elem **eie)
{
u64 disk_byte;
struct btrfs_key key;
struct btrfs_file_extent_item *fi;
int slot;
int nritems;
int extent_type;
int ret;
/*
* from the shared data ref, we only have the leaf but we need
* the key. thus, we must look into all items and see that we
* find one (some) with a reference to our extent item.
*/
nritems = btrfs_header_nritems(eb);
for (slot = 0; slot < nritems; ++slot) {
btrfs_item_key_to_cpu(eb, &key, slot);
if (key.type != BTRFS_EXTENT_DATA_KEY)
continue;
fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
extent_type = btrfs_file_extent_type(eb, fi);
if (extent_type == BTRFS_FILE_EXTENT_INLINE)
continue;
/* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
if (disk_byte != ctx->bytenr)
continue;
ret = check_extent_in_eb(ctx, &key, eb, fi, eie);
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
return ret;
}
return 0;
}
struct preftree {
struct rb_root_cached root;
unsigned int count;
};
#define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 }
struct preftrees {
struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */
struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */
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 {
struct btrfs_backref_share_check_ctx *ctx;
struct btrfs_root *root;
u64 inum;
u64 data_bytenr;
u64 data_extent_gen;
/*
* Counts number of inodes that refer to an extent (different inodes in
* the same root or different roots) that we could find. The sharedness
* check typically stops once this counter gets greater than 1, so it
* may not reflect the total number of inodes.
*/
int share_count;
/*
* The number of times we found our inode refers to the data extent we
* are determining the sharedness. In other words, how many file extent
* items we could find for our inode that point to our target data
* extent. The value we get here after finishing the extent sharedness
* check may be smaller than reality, but if it ends up being greater
* than 1, then we know for sure the inode has multiple file extent
* items that point to our inode, and we can safely assume it's useful
* to cache the sharedness check result.
*/
int self_ref_count;
bool have_delayed_delete_refs;
};
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)
{
btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
sizeof(struct prelim_ref),
0,
SLAB_MEM_SPREAD,
NULL);
if (!btrfs_prelim_ref_cache)
return -ENOMEM;
return 0;
}
void __cold btrfs_prelim_ref_exit(void)
{
kmem_cache_destroy(btrfs_prelim_ref_cache);
}
static void free_pref(struct prelim_ref *ref)
{
kmem_cache_free(btrfs_prelim_ref_cache, ref);
}
/*
* Return 0 when both refs are for the same block (and can be merged).
* A -1 return indicates ref1 is a 'lower' block than ref2, while 1
* indicates a 'higher' block.
*/
static int prelim_ref_compare(struct prelim_ref *ref1,
struct prelim_ref *ref2)
{
if (ref1->level < ref2->level)
return -1;
if (ref1->level > ref2->level)
return 1;
if (ref1->root_id < ref2->root_id)
return -1;
if (ref1->root_id > ref2->root_id)
return 1;
if (ref1->key_for_search.type < ref2->key_for_search.type)
return -1;
if (ref1->key_for_search.type > ref2->key_for_search.type)
return 1;
if (ref1->key_for_search.objectid < ref2->key_for_search.objectid)
return -1;
if (ref1->key_for_search.objectid > ref2->key_for_search.objectid)
return 1;
if (ref1->key_for_search.offset < ref2->key_for_search.offset)
return -1;
if (ref1->key_for_search.offset > ref2->key_for_search.offset)
return 1;
if (ref1->parent < ref2->parent)
return -1;
if (ref1->parent > ref2->parent)
return 1;
return 0;
}
static void update_share_count(struct share_check *sc, int oldcount,
int newcount, struct prelim_ref *newref)
{
if ((!sc) || (oldcount == 0 && newcount < 1))
return;
if (oldcount > 0 && newcount < 1)
sc->share_count--;
else if (oldcount < 1 && newcount > 0)
sc->share_count++;
if (newref->root_id == sc->root->root_key.objectid &&
newref->wanted_disk_byte == sc->data_bytenr &&
newref->key_for_search.objectid == sc->inum)
sc->self_ref_count += newref->count;
}
/*
* Add @newref to the @root rbtree, merging identical refs.
*
* 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 share_check *sc)
{
struct rb_root_cached *root;
struct rb_node **p;
struct rb_node *parent = NULL;
struct prelim_ref *ref;
int result;
bool leftmost = true;
root = &preftree->root;
p = &root->rb_root.rb_node;
while (*p) {
parent = *p;
ref = rb_entry(parent, struct prelim_ref, rbnode);
result = prelim_ref_compare(ref, newref);
if (result < 0) {
p = &(*p)->rb_left;
} else if (result > 0) {
p = &(*p)->rb_right;
leftmost = false;
} else {
/* Identical refs, merge them and free @newref */
struct extent_inode_elem *eie = ref->inode_list;
while (eie && eie->next)
eie = eie->next;
if (!eie)
ref->inode_list = newref->inode_list;
else
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, newref);
ref->count += newref->count;
free_pref(newref);
return;
}
}
update_share_count(sc, 0, newref->count, newref);
preftree->count++;
trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count);
rb_link_node(&newref->rbnode, parent, p);
rb_insert_color_cached(&newref->rbnode, root, leftmost);
}
/*
* Release the entire tree. We don't care about internal consistency so
* just free everything and then reset the tree root.
*/
static void prelim_release(struct preftree *preftree)
{
struct prelim_ref *ref, *next_ref;
rbtree_postorder_for_each_entry_safe(ref, next_ref,
&preftree->root.rb_root, rbnode) {
free_inode_elem_list(ref->inode_list);
free_pref(ref);
}
preftree->root = RB_ROOT_CACHED;
preftree->count = 0;
}
/*
* the rules for all callers of this function are:
* - obtaining the parent is the goal
* - if you add a key, you must know that it is a correct key
* - if you cannot add the parent or a correct key, then we will look into the
* block later to set a correct key
*
* delayed refs
* ============
* backref type | shared | indirect | shared | indirect
* information | tree | tree | data | data
* --------------------+--------+----------+--------+----------
* parent logical | y | - | - | -
* key to resolve | - | y | y | y
* tree block logical | - | - | - | -
* root for resolving | y | y | y | y
*
* - column 1: we've the parent -> done
* - column 2, 3, 4: we use the key to find the parent
*
* on disk refs (inline or keyed)
* ==============================
* backref type | shared | indirect | shared | indirect
* information | tree | tree | data | data
* --------------------+--------+----------+--------+----------
* parent logical | y | - | y | -
* key to resolve | - | - | - | y
* tree block logical | y | y | y | y
* root for resolving | - | y | y | y
*
* - column 1, 3: we've the parent -> done
* - column 2: we take the first key from the block to find the parent
* (see add_missing_keys)
* - column 4: we use the key to find the parent
*
* additional information that's available but not required to find the parent
* block might help in merging entries to gain some speed.
*/
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,
struct share_check *sc, gfp_t gfp_mask)
{
struct prelim_ref *ref;
if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
return 0;
ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
if (!ref)
return -ENOMEM;
ref->root_id = root_id;
if (key)
ref->key_for_search = *key;
else
memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
ref->inode_list = NULL;
ref->level = level;
ref->count = count;
ref->parent = parent;
ref->wanted_disk_byte = wanted_disk_byte;
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,
struct share_check *sc, gfp_t gfp_mask)
{
return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level,
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,
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, sc, gfp_mask);
}
static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr)
{
struct rb_node **p = &preftrees->direct.root.rb_root.rb_node;
struct rb_node *parent = NULL;
struct prelim_ref *ref = NULL;
struct prelim_ref target = {};
int result;
target.parent = bytenr;
while (*p) {
parent = *p;
ref = rb_entry(parent, struct prelim_ref, rbnode);
result = prelim_ref_compare(ref, &target);
if (result < 0)
p = &(*p)->rb_left;
else if (result > 0)
p = &(*p)->rb_right;
else
return 1;
}
return 0;
}
static int add_all_parents(struct btrfs_backref_walk_ctx *ctx,
struct btrfs_root *root, struct btrfs_path *path,
struct ulist *parents,
struct preftrees *preftrees, struct prelim_ref *ref,
int level)
{
int ret = 0;
int slot;
struct extent_buffer *eb;
struct btrfs_key key;
struct btrfs_key *key_for_search = &ref->key_for_search;
struct btrfs_file_extent_item *fi;
struct extent_inode_elem *eie = NULL, *old = NULL;
u64 disk_byte;
u64 wanted_disk_byte = ref->wanted_disk_byte;
u64 count = 0;
u64 data_offset;
if (level != 0) {
eb = path->nodes[level];
ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
if (ret < 0)
return ret;
return 0;
}
/*
* 1. We normally enter this function with the path already pointing to
* the first item to check. But sometimes, we may enter it with
* slot == nritems.
* 2. We are searching for normal backref but bytenr of this leaf
* matches shared data backref
* 3. The leaf owner is not equal to the root we are searching
*
* For these cases, go to the next leaf before we continue.
*/
eb = path->nodes[0];
if (path->slots[0] >= btrfs_header_nritems(eb) ||
is_shared_data_backref(preftrees, eb->start) ||
ref->root_id != btrfs_header_owner(eb)) {
if (ctx->time_seq == BTRFS_SEQ_LAST)
ret = btrfs_next_leaf(root, path);
else
ret = btrfs_next_old_leaf(root, path, ctx->time_seq);
}
while (!ret && count < ref->count) {
eb = path->nodes[0];
slot = path->slots[0];
btrfs_item_key_to_cpu(eb, &key, slot);
if (key.objectid != key_for_search->objectid ||
key.type != BTRFS_EXTENT_DATA_KEY)
break;
/*
* We are searching for normal backref but bytenr of this leaf
* matches shared data backref, OR
* the leaf owner is not equal to the root we are searching for
*/
if (slot == 0 &&
(is_shared_data_backref(preftrees, eb->start) ||
ref->root_id != btrfs_header_owner(eb))) {
if (ctx->time_seq == BTRFS_SEQ_LAST)
ret = btrfs_next_leaf(root, path);
else
ret = btrfs_next_old_leaf(root, path, ctx->time_seq);
continue;
}
fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
data_offset = btrfs_file_extent_offset(eb, fi);
if (disk_byte == wanted_disk_byte) {
eie = NULL;
old = NULL;
if (ref->key_for_search.offset == key.offset - data_offset)
count++;
else
goto next;
if (!ctx->ignore_extent_item_pos) {
ret = check_extent_in_eb(ctx, &key, eb, fi, &eie);
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
ret < 0)
break;
}
if (ret > 0)
goto next;
ret = ulist_add_merge_ptr(parents, eb->start,
eie, (void **)&old, GFP_NOFS);
if (ret < 0)
break;
if (!ret && !ctx->ignore_extent_item_pos) {
while (old->next)
old = old->next;
old->next = eie;
}
eie = NULL;
}
next:
if (ctx->time_seq == BTRFS_SEQ_LAST)
ret = btrfs_next_item(root, path);
else
ret = btrfs_next_old_item(root, path, ctx->time_seq);
}
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
free_inode_elem_list(eie);
else if (ret > 0)
ret = 0;
return ret;
}
/*
* resolve an indirect backref in the form (root_id, key, level)
* to a logical address
*/
static int resolve_indirect_ref(struct btrfs_backref_walk_ctx *ctx,
struct btrfs_path *path,
struct preftrees *preftrees,
struct prelim_ref *ref, struct ulist *parents)
{
struct btrfs_root *root;
struct extent_buffer *eb;
int ret = 0;
int root_level;
int level = ref->level;
struct btrfs_key search_key = ref->key_for_search;
/*
* If we're search_commit_root we could possibly be holding locks on
* other tree nodes. This happens when qgroups does backref walks when
* adding new delayed refs. To deal with this we need to look in cache
* for the root, and if we don't find it then we need to search the
* tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage
* here.
*/
if (path->search_commit_root)
root = btrfs_get_fs_root_commit_root(ctx->fs_info, path, ref->root_id);
else
root = btrfs_get_fs_root(ctx->fs_info, ref->root_id, false);
if (IS_ERR(root)) {
ret = PTR_ERR(root);
goto out_free;
}
if (!path->search_commit_root &&
test_bit(BTRFS_ROOT_DELETING, &root->state)) {
ret = -ENOENT;
goto out;
}
if (btrfs_is_testing(ctx->fs_info)) {
ret = -ENOENT;
goto out;
}
if (path->search_commit_root)
root_level = btrfs_header_level(root->commit_root);
else if (ctx->time_seq == BTRFS_SEQ_LAST)
root_level = btrfs_header_level(root->node);
else
root_level = btrfs_old_root_level(root, ctx->time_seq);
if (root_level + 1 == level)
goto out;
/*
* We can often find data backrefs with an offset that is too large
* (>= LLONG_MAX, maximum allowed file offset) due to underflows when
* subtracting a file's offset with the data offset of its
* corresponding extent data item. This can happen for example in the
* clone ioctl.
*
* So if we detect such case we set the search key's offset to zero to
* make sure we will find the matching file extent item at
* add_all_parents(), otherwise we will miss it because the offset
* taken form the backref is much larger then the offset of the file
* extent item. This can make us scan a very large number of file
* extent items, but at least it will not make us miss any.
*
* This is an ugly workaround for a behaviour that should have never
* existed, but it does and a fix for the clone ioctl would touch a lot
* of places, cause backwards incompatibility and would not fix the
* problem for extents cloned with older kernels.
*/
if (search_key.type == BTRFS_EXTENT_DATA_KEY &&
search_key.offset >= LLONG_MAX)
search_key.offset = 0;
path->lowest_level = level;
if (ctx->time_seq == BTRFS_SEQ_LAST)
ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
else
ret = btrfs_search_old_slot(root, &search_key, path, ctx->time_seq);
btrfs_debug(ctx->fs_info,
"search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)",
ref->root_id, level, ref->count, ret,
ref->key_for_search.objectid, ref->key_for_search.type,
ref->key_for_search.offset);
if (ret < 0)
goto out;
eb = path->nodes[level];
while (!eb) {
if (WARN_ON(!level)) {
ret = 1;
goto out;
}
level--;
eb = path->nodes[level];
}
ret = add_all_parents(ctx, root, path, parents, preftrees, ref, level);
out:
btrfs_put_root(root);
out_free:
path->lowest_level = 0;
btrfs_release_path(path);
return ret;
}
static struct extent_inode_elem *
unode_aux_to_inode_list(struct ulist_node *node)
{
if (!node)
return NULL;
return (struct extent_inode_elem *)(uintptr_t)node->aux;
}
static void free_leaf_list(struct ulist *ulist)
{
struct ulist_node *node;
struct ulist_iterator uiter;
ULIST_ITER_INIT(&uiter);
while ((node = ulist_next(ulist, &uiter)))
free_inode_elem_list(unode_aux_to_inode_list(node));
ulist_free(ulist);
}
/*
* We maintain three separate rbtrees: one for direct refs, one for
* indirect refs which have a key, and one for indirect refs which do not
* have a key. Each tree does merge on insertion.
*
* Once all of the references are located, we iterate over the tree of
* indirect refs with missing keys. An appropriate key is located and
* the ref is moved onto the tree for indirect refs. After all missing
* keys are thus located, we iterate over the indirect ref tree, resolve
* each reference, and then insert the resolved reference onto the
* direct tree (merging there too).
*
* New backrefs (i.e., for parent nodes) are added to the appropriate
* rbtree as they are encountered. The new backrefs are subsequently
* resolved as above.
*/
static int resolve_indirect_refs(struct btrfs_backref_walk_ctx *ctx,
struct btrfs_path *path,
struct preftrees *preftrees,
struct share_check *sc)
{
int err;
int ret = 0;
struct ulist *parents;
struct ulist_node *node;
struct ulist_iterator uiter;
struct rb_node *rnode;
parents = ulist_alloc(GFP_NOFS);
if (!parents)
return -ENOMEM;
/*
* We could trade memory usage for performance here by iterating
* the tree, allocating new refs for each insertion, and then
* freeing the entire indirect tree when we're done. In some test
* cases, the tree can grow quite large (~200k objects).
*/
while ((rnode = rb_first_cached(&preftrees->indirect.root))) {
struct prelim_ref *ref;
ref = rb_entry(rnode, struct prelim_ref, rbnode);
if (WARN(ref->parent,
"BUG: direct ref found in indirect tree")) {
ret = -EINVAL;
goto out;
}
rb_erase_cached(&ref->rbnode, &preftrees->indirect.root);
preftrees->indirect.count--;
if (ref->count == 0) {
free_pref(ref);
continue;
}
if (sc && ref->root_id != sc->root->root_key.objectid) {
free_pref(ref);
ret = BACKREF_FOUND_SHARED;
goto out;
}
err = resolve_indirect_ref(ctx, path, preftrees, ref, parents);
/*
* we can only tolerate ENOENT,otherwise,we should catch error
* and return directly.
*/
if (err == -ENOENT) {
prelim_ref_insert(ctx->fs_info, &preftrees->direct, ref,
NULL);
continue;
} else if (err) {
free_pref(ref);
ret = err;
goto out;
}
/* we put the first parent into the ref at hand */
ULIST_ITER_INIT(&uiter);
node = ulist_next(parents, &uiter);
ref->parent = node ? node->val : 0;
ref->inode_list = unode_aux_to_inode_list(node);
/* Add a prelim_ref(s) for any other parent(s). */
while ((node = ulist_next(parents, &uiter))) {
struct prelim_ref *new_ref;
new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
GFP_NOFS);
if (!new_ref) {
free_pref(ref);
ret = -ENOMEM;
goto out;
}
memcpy(new_ref, ref, sizeof(*ref));
new_ref->parent = node->val;
new_ref->inode_list = unode_aux_to_inode_list(node);
prelim_ref_insert(ctx->fs_info, &preftrees->direct,
new_ref, NULL);
}
/*
* Now it's a direct ref, put it in the direct tree. We must
* do this last because the ref could be merged/freed here.
*/
prelim_ref_insert(ctx->fs_info, &preftrees->direct, ref, NULL);
ulist_reinit(parents);
cond_resched();
}
out:
/*
* We may have inode lists attached to refs in the parents ulist, so we
* must free them before freeing the ulist and its refs.
*/
free_leaf_list(parents);
return ret;
}
/*
* read tree blocks and add keys where required.
*/
static int add_missing_keys(struct btrfs_fs_info *fs_info,
struct preftrees *preftrees, bool lock)
{
struct prelim_ref *ref;
struct extent_buffer *eb;
struct preftree *tree = &preftrees->indirect_missing_keys;
struct rb_node *node;
while ((node = rb_first_cached(&tree->root))) {
struct btrfs_tree_parent_check check = { 0 };
ref = rb_entry(node, struct prelim_ref, rbnode);
rb_erase_cached(node, &tree->root);
BUG_ON(ref->parent); /* should not be a direct ref */
BUG_ON(ref->key_for_search.type);
BUG_ON(!ref->wanted_disk_byte);
check.level = ref->level - 1;
check.owner_root = ref->root_id;
eb = read_tree_block(fs_info, ref->wanted_disk_byte, &check);
if (IS_ERR(eb)) {
free_pref(ref);
return PTR_ERR(eb);
}
if (!extent_buffer_uptodate(eb)) {
free_pref(ref);
free_extent_buffer(eb);
return -EIO;
}
if (lock)
btrfs_tree_read_lock(eb);
if (btrfs_header_level(eb) == 0)
btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
else
btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
if (lock)
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL);
cond_resched();
}
return 0;
}
/*
* add all currently queued delayed refs from this head whose seq nr is
* smaller or equal that seq to the list
*/
static int add_delayed_refs(const struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_head *head, u64 seq,
struct preftrees *preftrees, struct share_check *sc)
{
struct btrfs_delayed_ref_node *node;
struct btrfs_key key;
struct rb_node *n;
int count;
int ret = 0;
spin_lock(&head->lock);
for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {
node = rb_entry(n, struct btrfs_delayed_ref_node,
ref_node);
if (node->seq > seq)
continue;
switch (node->action) {
case BTRFS_ADD_DELAYED_EXTENT:
case BTRFS_UPDATE_DELAYED_HEAD:
WARN_ON(1);
continue;
case BTRFS_ADD_DELAYED_REF:
count = node->ref_mod;
break;
case BTRFS_DROP_DELAYED_REF:
count = node->ref_mod * -1;
break;
default:
BUG();
}
switch (node->type) {
case BTRFS_TREE_BLOCK_REF_KEY: {
/* NORMAL INDIRECT METADATA backref */
struct btrfs_delayed_tree_ref *ref;
struct btrfs_key *key_ptr = NULL;
if (head->extent_op && head->extent_op->update_key) {
btrfs_disk_key_to_cpu(&key, &head->extent_op->key);
key_ptr = &key;
}
ref = btrfs_delayed_node_to_tree_ref(node);
ret = add_indirect_ref(fs_info, preftrees, ref->root,
key_ptr, ref->level + 1,
node->bytenr, count, sc,
GFP_ATOMIC);
break;
}
case BTRFS_SHARED_BLOCK_REF_KEY: {
/* SHARED DIRECT METADATA backref */
struct btrfs_delayed_tree_ref *ref;
ref = btrfs_delayed_node_to_tree_ref(node);
ret = add_direct_ref(fs_info, preftrees, ref->level + 1,
ref->parent, node->bytenr, count,
sc, GFP_ATOMIC);
break;
}
case BTRFS_EXTENT_DATA_REF_KEY: {
/* NORMAL INDIRECT DATA backref */
struct btrfs_delayed_data_ref *ref;
ref = btrfs_delayed_node_to_data_ref(node);
key.objectid = ref->objectid;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = ref->offset;
/*
* If we have a share check context and a reference for
* another inode, we can't exit immediately. This is
* because even if this is a BTRFS_ADD_DELAYED_REF
* reference we may find next a BTRFS_DROP_DELAYED_REF
* which cancels out this ADD reference.
*
* If this is a DROP reference and there was no previous
* ADD reference, then we need to signal that when we
* process references from the extent tree (through
* add_inline_refs() and add_keyed_refs()), we should
* not exit early if we find a reference for another
* inode, because one of the delayed DROP references
* may cancel that reference in the extent tree.
*/
if (sc && count < 0)
sc->have_delayed_delete_refs = true;
ret = add_indirect_ref(fs_info, preftrees, ref->root,
&key, 0, node->bytenr, count, sc,
GFP_ATOMIC);
break;
}
case BTRFS_SHARED_DATA_REF_KEY: {
/* SHARED DIRECT FULL backref */
struct btrfs_delayed_data_ref *ref;
ref = btrfs_delayed_node_to_data_ref(node);
ret = add_direct_ref(fs_info, preftrees, 0, ref->parent,
node->bytenr, count, sc,
GFP_ATOMIC);
break;
}
default:
WARN_ON(1);
}
/*
* 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);
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(struct btrfs_backref_walk_ctx *ctx,
struct btrfs_path *path,
int *info_level, struct preftrees *preftrees,
struct share_check *sc)
{
int ret = 0;
int slot;
struct extent_buffer *leaf;
struct btrfs_key key;
struct btrfs_key found_key;
unsigned long ptr;
unsigned long end;
struct btrfs_extent_item *ei;
u64 flags;
u64 item_size;
/*
* enumerate all inline refs
*/
leaf = path->nodes[0];
slot = path->slots[0];
item_size = btrfs_item_size(leaf, slot);
BUG_ON(item_size < sizeof(*ei));
ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
if (ctx->check_extent_item) {
ret = ctx->check_extent_item(ctx->bytenr, ei, leaf, ctx->user_ctx);
if (ret)
return ret;
}
flags = btrfs_extent_flags(leaf, ei);
btrfs_item_key_to_cpu(leaf, &found_key, slot);
ptr = (unsigned long)(ei + 1);
end = (unsigned long)ei + item_size;
if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
struct btrfs_tree_block_info *info;
info = (struct btrfs_tree_block_info *)ptr;
*info_level = btrfs_tree_block_level(leaf, info);
ptr += sizeof(struct btrfs_tree_block_info);
BUG_ON(ptr > end);
} else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
*info_level = found_key.offset;
} else {
BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
}
while (ptr < end) {
struct btrfs_extent_inline_ref *iref;
u64 offset;
int type;
iref = (struct btrfs_extent_inline_ref *)ptr;
type = btrfs_get_extent_inline_ref_type(leaf, iref,
BTRFS_REF_TYPE_ANY);
if (type == BTRFS_REF_TYPE_INVALID)
return -EUCLEAN;
offset = btrfs_extent_inline_ref_offset(leaf, iref);
switch (type) {
case BTRFS_SHARED_BLOCK_REF_KEY:
ret = add_direct_ref(ctx->fs_info, preftrees,
*info_level + 1, offset,
ctx->bytenr, 1, NULL, GFP_NOFS);
break;
case BTRFS_SHARED_DATA_REF_KEY: {
struct btrfs_shared_data_ref *sdref;
int count;
sdref = (struct btrfs_shared_data_ref *)(iref + 1);
count = btrfs_shared_data_ref_count(leaf, sdref);
ret = add_direct_ref(ctx->fs_info, preftrees, 0, offset,
ctx->bytenr, count, sc, GFP_NOFS);
break;
}
case BTRFS_TREE_BLOCK_REF_KEY:
ret = add_indirect_ref(ctx->fs_info, preftrees, offset,
NULL, *info_level + 1,
ctx->bytenr, 1, NULL, GFP_NOFS);
break;
case BTRFS_EXTENT_DATA_REF_KEY: {
struct btrfs_extent_data_ref *dref;
int count;
u64 root;
dref = (struct btrfs_extent_data_ref *)(&iref->offset);
count = btrfs_extent_data_ref_count(leaf, dref);
key.objectid = btrfs_extent_data_ref_objectid(leaf,
dref);
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = btrfs_extent_data_ref_offset(leaf, dref);
if (sc && key.objectid != sc->inum &&
!sc->have_delayed_delete_refs) {
ret = BACKREF_FOUND_SHARED;
break;
}
root = btrfs_extent_data_ref_root(leaf, dref);
if (!ctx->skip_data_ref ||
!ctx->skip_data_ref(root, key.objectid, key.offset,
ctx->user_ctx))
ret = add_indirect_ref(ctx->fs_info, preftrees,
root, &key, 0, ctx->bytenr,
count, sc, GFP_NOFS);
break;
}
default:
WARN_ON(1);
}
if (ret)
return ret;
ptr += btrfs_extent_inline_ref_size(type);
}
return 0;
}
/*
* 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_backref_walk_ctx *ctx,
struct btrfs_root *extent_root,
struct btrfs_path *path,
int info_level, struct preftrees *preftrees,
struct share_check *sc)
{
struct btrfs_fs_info *fs_info = extent_root->fs_info;
int ret;
int slot;
struct extent_buffer *leaf;
struct btrfs_key key;
while (1) {
ret = btrfs_next_item(extent_root, path);
if (ret < 0)
break;
if (ret) {
ret = 0;
break;
}
slot = path->slots[0];
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != ctx->bytenr)
break;
if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
continue;
if (key.type > BTRFS_SHARED_DATA_REF_KEY)
break;
switch (key.type) {
case BTRFS_SHARED_BLOCK_REF_KEY:
/* SHARED DIRECT METADATA backref */
ret = add_direct_ref(fs_info, preftrees,
info_level + 1, key.offset,
ctx->bytenr, 1, NULL, GFP_NOFS);
break;
case BTRFS_SHARED_DATA_REF_KEY: {
/* SHARED DIRECT FULL backref */
struct btrfs_shared_data_ref *sdref;
int count;
sdref = btrfs_item_ptr(leaf, slot,
struct btrfs_shared_data_ref);
count = btrfs_shared_data_ref_count(leaf, sdref);
ret = add_direct_ref(fs_info, preftrees, 0,
key.offset, ctx->bytenr, count,
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, ctx->bytenr,
1, NULL, GFP_NOFS);
break;
case BTRFS_EXTENT_DATA_REF_KEY: {
/* NORMAL INDIRECT DATA backref */
struct btrfs_extent_data_ref *dref;
int count;
u64 root;
dref = btrfs_item_ptr(leaf, slot,
struct btrfs_extent_data_ref);
count = btrfs_extent_data_ref_count(leaf, dref);
key.objectid = btrfs_extent_data_ref_objectid(leaf,
dref);
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = btrfs_extent_data_ref_offset(leaf, dref);
if (sc && key.objectid != sc->inum &&
!sc->have_delayed_delete_refs) {
ret = BACKREF_FOUND_SHARED;
break;
}
root = btrfs_extent_data_ref_root(leaf, dref);
if (!ctx->skip_data_ref ||
!ctx->skip_data_ref(root, key.objectid, key.offset,
ctx->user_ctx))
ret = add_indirect_ref(fs_info, preftrees, root,
&key, 0, ctx->bytenr,
count, sc, GFP_NOFS);
break;
}
default:
WARN_ON(1);
}
if (ret)
return ret;
}
return ret;
}
/*
* The caller has joined a transaction or is holding a read lock on the
* fs_info->commit_root_sem semaphore, so no need to worry about the root's last
* snapshot field changing while updating or checking the cache.
*/
static bool lookup_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx,
struct btrfs_root *root,
u64 bytenr, int level, bool *is_shared)
{
struct btrfs_backref_shared_cache_entry *entry;
if (!ctx->use_path_cache)
return false;
if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
return false;
/*
* Level -1 is used for the data extent, which is not reliable to cache
* because its reference count can increase or decrease without us
* realizing. We cache results only for extent buffers that lead from
* the root node down to the leaf with the file extent item.
*/
ASSERT(level >= 0);
entry = &ctx->path_cache_entries[level];
/* Unused cache entry or being used for some other extent buffer. */
if (entry->bytenr != bytenr)
return false;
/*
* We cached a false result, but the last snapshot generation of the
* root changed, so we now have a snapshot. Don't trust the result.
*/
if (!entry->is_shared &&
entry->gen != btrfs_root_last_snapshot(&root->root_item))
return false;
/*
* If we cached a true result and the last generation used for dropping
* a root changed, we can not trust the result, because the dropped root
* could be a snapshot sharing this extent buffer.
*/
if (entry->is_shared &&
entry->gen != btrfs_get_last_root_drop_gen(root->fs_info))
return false;
*is_shared = entry->is_shared;
/*
* If the node at this level is shared, than all nodes below are also
* shared. Currently some of the nodes below may be marked as not shared
* because we have just switched from one leaf to another, and switched
* also other nodes above the leaf and below the current level, so mark
* them as shared.
*/
if (*is_shared) {
for (int i = 0; i < level; i++) {
ctx->path_cache_entries[i].is_shared = true;
ctx->path_cache_entries[i].gen = entry->gen;
}
}
return true;
}
/*
* The caller has joined a transaction or is holding a read lock on the
* fs_info->commit_root_sem semaphore, so no need to worry about the root's last
* snapshot field changing while updating or checking the cache.
*/
static void store_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx,
struct btrfs_root *root,
u64 bytenr, int level, bool is_shared)
{
struct btrfs_backref_shared_cache_entry *entry;
u64 gen;
if (!ctx->use_path_cache)
return;
if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL))
return;
/*
* Level -1 is used for the data extent, which is not reliable to cache
* because its reference count can increase or decrease without us
* realizing. We cache results only for extent buffers that lead from
* the root node down to the leaf with the file extent item.
*/
ASSERT(level >= 0);
if (is_shared)
gen = btrfs_get_last_root_drop_gen(root->fs_info);
else
gen = btrfs_root_last_snapshot(&root->root_item);
entry = &ctx->path_cache_entries[level];
entry->bytenr = bytenr;
entry->is_shared = is_shared;
entry->gen = gen;
/*
* If we found an extent buffer is shared, set the cache result for all
* extent buffers below it to true. As nodes in the path are COWed,
* their sharedness is moved to their children, and if a leaf is COWed,
* then the sharedness of a data extent becomes direct, the refcount of
* data extent is increased in the extent item at the extent tree.
*/
if (is_shared) {
for (int i = 0; i < level; i++) {
entry = &ctx->path_cache_entries[i];
entry->is_shared = is_shared;
entry->gen = gen;
}
}
}
/*
* this adds all existing backrefs (inline backrefs, backrefs and delayed
* refs) for the given bytenr to the refs list, merges duplicates and resolves
* indirect refs to their parent bytenr.
* When roots are found, they're added to the roots list
*
* @ctx: Backref walking context object, must be not NULL.
* @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_backref_walk_ctx *ctx,
struct share_check *sc)
{
struct btrfs_root *root = btrfs_extent_root(ctx->fs_info, ctx->bytenr);
struct btrfs_key key;
struct btrfs_path *path;
struct btrfs_delayed_ref_root *delayed_refs = NULL;
struct btrfs_delayed_ref_head *head;
int info_level = 0;
int ret;
struct prelim_ref *ref;
struct rb_node *node;
struct extent_inode_elem *eie = NULL;
struct preftrees preftrees = {
.direct = PREFTREE_INIT,
.indirect = PREFTREE_INIT,
.indirect_missing_keys = PREFTREE_INIT
};
/* Roots ulist is not needed when using a sharedness check context. */
if (sc)
ASSERT(ctx->roots == NULL);
key.objectid = ctx->bytenr;
key.offset = (u64)-1;
if (btrfs_fs_incompat(ctx->fs_info, SKINNY_METADATA))
key.type = BTRFS_METADATA_ITEM_KEY;
else
key.type = BTRFS_EXTENT_ITEM_KEY;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
if (!ctx->trans) {
path->search_commit_root = 1;
path->skip_locking = 1;
}
if (ctx->time_seq == BTRFS_SEQ_LAST)
path->skip_locking = 1;
again:
head = NULL;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
goto out;
if (ret == 0) {
/* This shouldn't happen, indicates a bug or fs corruption. */
ASSERT(ret != 0);
ret = -EUCLEAN;
goto out;
}
if (ctx->trans && likely(ctx->trans->type != __TRANS_DUMMY) &&
ctx->time_seq != BTRFS_SEQ_LAST) {
/*
* We have a specific time_seq we care about and trans which
* means we have the path lock, we need to grab the ref head and
* lock it so we have a consistent view of the refs at the given
* time.
*/
delayed_refs = &ctx->trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
head = btrfs_find_delayed_ref_head(delayed_refs, ctx->bytenr);
if (head) {
if (!mutex_trylock(&head->mutex)) {
refcount_inc(&head->refs);
spin_unlock(&delayed_refs->lock);
btrfs_release_path(path);
/*
* Mutex was contended, block until it's
* released and try again
*/
mutex_lock(&head->mutex);
mutex_unlock(&head->mutex);
btrfs_put_delayed_ref_head(head);
goto again;
}
spin_unlock(&delayed_refs->lock);
ret = add_delayed_refs(ctx->fs_info, head, ctx->time_seq,
&preftrees, sc);
mutex_unlock(&head->mutex);
if (ret)
goto out;
} else {
spin_unlock(&delayed_refs->lock);
}
}
if (path->slots[0]) {
struct extent_buffer *leaf;
int slot;
path->slots[0]--;
leaf = path->nodes[0];
slot = path->slots[0];
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid == ctx->bytenr &&
(key.type == BTRFS_EXTENT_ITEM_KEY ||
key.type == BTRFS_METADATA_ITEM_KEY)) {
ret = add_inline_refs(ctx, path, &info_level,
&preftrees, sc);
if (ret)
goto out;
ret = add_keyed_refs(ctx, root, path, info_level,
&preftrees, sc);
if (ret)
goto out;
}
}
/*
* If we have a share context and we reached here, it means the extent
* is not directly shared (no multiple reference items for it),
* otherwise we would have exited earlier with a return value of
* BACKREF_FOUND_SHARED after processing delayed references or while
* processing inline or keyed references from the extent tree.
* The extent may however be indirectly shared through shared subtrees
* as a result from creating snapshots, so we determine below what is
* its parent node, in case we are dealing with a metadata extent, or
* what's the leaf (or leaves), from a fs tree, that has a file extent
* item pointing to it in case we are dealing with a data extent.
*/
ASSERT(extent_is_shared(sc) == 0);
/*
* If we are here for a data extent and we have a share_check structure
* it means the data extent is not directly shared (does not have
* multiple reference items), so we have to check if a path in the fs
* tree (going from the root node down to the leaf that has the file
* extent item pointing to the data extent) is shared, that is, if any
* of the extent buffers in the path is referenced by other trees.
*/
if (sc && ctx->bytenr == sc->data_bytenr) {
/*
* If our data extent is from a generation more recent than the
* last generation used to snapshot the root, then we know that
* it can not be shared through subtrees, so we can skip
* resolving indirect references, there's no point in
* determining the extent buffers for the path from the fs tree
* root node down to the leaf that has the file extent item that
* points to the data extent.
*/
if (sc->data_extent_gen >
btrfs_root_last_snapshot(&sc->root->root_item)) {
ret = BACKREF_FOUND_NOT_SHARED;
goto out;
}
/*
* If we are only determining if a data extent is shared or not
* and the corresponding file extent item is located in the same
* leaf as the previous file extent item, we can skip resolving
* indirect references for a data extent, since the fs tree path
* is the same (same leaf, so same path). We skip as long as the
* cached result for the leaf is valid and only if there's only
* one file extent item pointing to the data extent, because in
* the case of multiple file extent items, they may be located
* in different leaves and therefore we have multiple paths.
*/
if (sc->ctx->curr_leaf_bytenr == sc->ctx->prev_leaf_bytenr &&
sc->self_ref_count == 1) {
bool cached;
bool is_shared;
cached = lookup_backref_shared_cache(sc->ctx, sc->root,
sc->ctx->curr_leaf_bytenr,
0, &is_shared);
if (cached) {
if (is_shared)
ret = BACKREF_FOUND_SHARED;
else
ret = BACKREF_FOUND_NOT_SHARED;
goto out;
}
}
}
btrfs_release_path(path);
ret = add_missing_keys(ctx->fs_info, &preftrees, path->skip_locking == 0);
if (ret)
goto out;
WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root));
ret = resolve_indirect_refs(ctx, path, &preftrees, sc);
if (ret)
goto out;
WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root));
/*
* This walks the tree of merged and resolved refs. Tree blocks are
* read in as needed. Unique entries are added to the ulist, and
* the list of found roots is updated.
*
* We release the entire tree in one go before returning.
*/
node = rb_first_cached(&preftrees.direct.root);
while (node) {
ref = rb_entry(node, struct prelim_ref, rbnode);
node = rb_next(&ref->rbnode);
/*
* ref->count < 0 can happen here if there are delayed
* refs with a node->action of BTRFS_DROP_DELAYED_REF.
* prelim_ref_insert() relies on this when merging
* identical refs to keep the overall count correct.
* prelim_ref_insert() will merge only those refs
* which compare identically. Any refs having
* e.g. different offsets would not be merged,
* and would retain their original ref->count < 0.
*/
if (ctx->roots && ref->count && ref->root_id && ref->parent == 0) {
/* no parent == root of tree */
ret = ulist_add(ctx->roots, ref->root_id, 0, GFP_NOFS);
if (ret < 0)
goto out;
}
if (ref->count && ref->parent) {
if (!ctx->ignore_extent_item_pos && !ref->inode_list &&
ref->level == 0) {
struct btrfs_tree_parent_check check = { 0 };
struct extent_buffer *eb;
check.level = ref->level;
eb = read_tree_block(ctx->fs_info, ref->parent,
&check);
if (IS_ERR(eb)) {
ret = PTR_ERR(eb);
goto out;
}
if (!extent_buffer_uptodate(eb)) {
free_extent_buffer(eb);
ret = -EIO;
goto out;
}
if (!path->skip_locking)
btrfs_tree_read_lock(eb);
ret = find_extent_in_eb(ctx, eb, &eie);
if (!path->skip_locking)
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
ret < 0)
goto out;
ref->inode_list = eie;
/*
* We transferred the list ownership to the ref,
* so set to NULL to avoid a double free in case
* an error happens after this.
*/
eie = NULL;
}
ret = ulist_add_merge_ptr(ctx->refs, ref->parent,
ref->inode_list,
(void **)&eie, GFP_NOFS);
if (ret < 0)
goto out;
if (!ret && !ctx->ignore_extent_item_pos) {
/*
* We've recorded that parent, so we must extend
* its inode list here.
*
* However if there was corruption we may not
* have found an eie, return an error in this
* case.
*/
ASSERT(eie);
if (!eie) {
ret = -EUCLEAN;
goto out;
}
while (eie->next)
eie = eie->next;
eie->next = ref->inode_list;
}
eie = NULL;
/*
* We have transferred the inode list ownership from
* this ref to the ref we added to the 'refs' ulist.
* So set this ref's inode list to NULL to avoid
* use-after-free when our caller uses it or double
* frees in case an error happens before we return.
*/
ref->inode_list = NULL;
}
cond_resched();
}
out:
btrfs_free_path(path);
prelim_release(&preftrees.direct);
prelim_release(&preftrees.indirect);
prelim_release(&preftrees.indirect_missing_keys);
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
free_inode_elem_list(eie);
return ret;
}
/*
* Finds all leaves with a reference to the specified combination of
* @ctx->bytenr and @ctx->extent_item_pos. The bytenr of the found leaves are
* added to the ulist at @ctx->refs, and that ulist is allocated by this
* function. The caller should free the ulist with free_leaf_list() if
* @ctx->ignore_extent_item_pos is false, otherwise a fimple ulist_free() is
* enough.
*
* Returns 0 on success and < 0 on error. On error @ctx->refs is not allocated.
*/
int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx)
{
int ret;
ASSERT(ctx->refs == NULL);
ctx->refs = ulist_alloc(GFP_NOFS);
if (!ctx->refs)
return -ENOMEM;
ret = find_parent_nodes(ctx, NULL);
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
(ret < 0 && ret != -ENOENT)) {
free_leaf_list(ctx->refs);
ctx->refs = NULL;
return ret;
}
return 0;
}
/*
* Walk all backrefs for a given extent to find all roots that reference this
* extent. Walking a backref means finding all extents that reference this
* extent and in turn walk the backrefs of those, too. Naturally this is a
* recursive process, but here it is implemented in an iterative fashion: We
* find all referencing extents for the extent in question and put them on a
* list. In turn, we find all referencing extents for those, further appending
* to the list. The way we iterate the list allows adding more elements after
* the current while iterating. The process stops when we reach the end of the
* list.
*
* Found roots are added to @ctx->roots, which is allocated by this function if
* it points to NULL, in which case the caller is responsible for freeing it
* after it's not needed anymore.
* This function requires @ctx->refs to be NULL, as it uses it for allocating a
* ulist to do temporary work, and frees it before returning.
*
* Returns 0 on success, < 0 on error.
*/
static int btrfs_find_all_roots_safe(struct btrfs_backref_walk_ctx *ctx)
{
const u64 orig_bytenr = ctx->bytenr;
const bool orig_ignore_extent_item_pos = ctx->ignore_extent_item_pos;
bool roots_ulist_allocated = false;
struct ulist_iterator uiter;
int ret = 0;
ASSERT(ctx->refs == NULL);
ctx->refs = ulist_alloc(GFP_NOFS);
if (!ctx->refs)
return -ENOMEM;
if (!ctx->roots) {
ctx->roots = ulist_alloc(GFP_NOFS);
if (!ctx->roots) {
ulist_free(ctx->refs);
ctx->refs = NULL;
return -ENOMEM;
}
roots_ulist_allocated = true;
}
ctx->ignore_extent_item_pos = true;
ULIST_ITER_INIT(&uiter);
while (1) {
struct ulist_node *node;
ret = find_parent_nodes(ctx, NULL);
if (ret < 0 && ret != -ENOENT) {
if (roots_ulist_allocated) {
ulist_free(ctx->roots);
ctx->roots = NULL;
}
break;
}
ret = 0;
node = ulist_next(ctx->refs, &uiter);
if (!node)
break;
ctx->bytenr = node->val;
cond_resched();
}
ulist_free(ctx->refs);
ctx->refs = NULL;
ctx->bytenr = orig_bytenr;
ctx->ignore_extent_item_pos = orig_ignore_extent_item_pos;
return ret;
}
int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
bool skip_commit_root_sem)
{
int ret;
if (!ctx->trans && !skip_commit_root_sem)
down_read(&ctx->fs_info->commit_root_sem);
ret = btrfs_find_all_roots_safe(ctx);
if (!ctx->trans && !skip_commit_root_sem)
up_read(&ctx->fs_info->commit_root_sem);
return ret;
}
struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void)
{
struct btrfs_backref_share_check_ctx *ctx;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return NULL;
ulist_init(&ctx->refs);
return ctx;
}
void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx)
{
if (!ctx)
return;
ulist_release(&ctx->refs);
kfree(ctx);
}
/*
* Check if a data extent is shared or not.
*
* @inode: The inode whose extent we are checking.
* @bytenr: Logical bytenr of the extent we are checking.
* @extent_gen: Generation of the extent (file extent item) or 0 if it is
* not known.
* @ctx: A backref sharedness check context.
*
* btrfs_is_data_extent_shared uses the backref walking code but will short
* circuit as soon as it finds a root or inode that doesn't match the
* one passed in. This provides a significant performance benefit for
* callers (such as fiemap) which want to know whether the extent is
* shared but do not need a ref count.
*
* This attempts to attach to the running transaction in order to account for
* delayed refs, but continues on even when no running transaction exists.
*
* Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
*/
int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
u64 extent_gen,
struct btrfs_backref_share_check_ctx *ctx)
{
struct btrfs_backref_walk_ctx walk_ctx = { 0 };
struct btrfs_root *root = inode->root;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_trans_handle *trans;
struct ulist_iterator uiter;
struct ulist_node *node;
struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem);
int ret = 0;
struct share_check shared = {
.ctx = ctx,
.root = root,
.inum = btrfs_ino(inode),
.data_bytenr = bytenr,
.data_extent_gen = extent_gen,
.share_count = 0,
.self_ref_count = 0,
.have_delayed_delete_refs = false,
};
int level;
for (int i = 0; i < BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE; i++) {
if (ctx->prev_extents_cache[i].bytenr == bytenr)
return ctx->prev_extents_cache[i].is_shared;
}
ulist_init(&ctx->refs);
trans = btrfs_join_transaction_nostart(root);
if (IS_ERR(trans)) {
if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) {
ret = PTR_ERR(trans);
goto out;
}
trans = NULL;
down_read(&fs_info->commit_root_sem);
} else {
btrfs_get_tree_mod_seq(fs_info, &elem);
walk_ctx.time_seq = elem.seq;
}
walk_ctx.ignore_extent_item_pos = true;
walk_ctx.trans = trans;
walk_ctx.fs_info = fs_info;
walk_ctx.refs = &ctx->refs;
/* -1 means we are in the bytenr of the data extent. */
level = -1;
ULIST_ITER_INIT(&uiter);
ctx->use_path_cache = true;
while (1) {
bool is_shared;
bool cached;
walk_ctx.bytenr = bytenr;
ret = find_parent_nodes(&walk_ctx, &shared);
if (ret == BACKREF_FOUND_SHARED ||
ret == BACKREF_FOUND_NOT_SHARED) {
/* If shared must return 1, otherwise return 0. */
ret = (ret == BACKREF_FOUND_SHARED) ? 1 : 0;
if (level >= 0)
store_backref_shared_cache(ctx, root, bytenr,
level, ret == 1);
break;
}
if (ret < 0 && ret != -ENOENT)
break;
ret = 0;
/*
* If our data extent was not directly shared (without multiple
* reference items), than it might have a single reference item
* with a count > 1 for the same offset, which means there are 2
* (or more) file extent items that point to the data extent -
* this happens when a file extent item needs to be split and
* then one item gets moved to another leaf due to a b+tree leaf
* split when inserting some item. In this case the file extent
* items may be located in different leaves and therefore some
* of the leaves may be referenced through shared subtrees while
* others are not. Since our extent buffer cache only works for
* a single path (by far the most common case and simpler to
* deal with), we can not use it if we have multiple leaves
* (which implies multiple paths).
*/
if (level == -1 && ctx->refs.nnodes > 1)
ctx->use_path_cache = false;
if (level >= 0)
store_backref_shared_cache(ctx, root, bytenr,
level, false);
node = ulist_next(&ctx->refs, &uiter);
if (!node)
break;
bytenr = node->val;
level++;
cached = lookup_backref_shared_cache(ctx, root, bytenr, level,
&is_shared);
if (cached) {
ret = (is_shared ? 1 : 0);
break;
}
shared.share_count = 0;
shared.have_delayed_delete_refs = false;
cond_resched();
}
/*
* Cache the sharedness result for the data extent if we know our inode
* has more than 1 file extent item that refers to the data extent.
*/
if (ret >= 0 && shared.self_ref_count > 1) {
int slot = ctx->prev_extents_cache_slot;
ctx->prev_extents_cache[slot].bytenr = shared.data_bytenr;
ctx->prev_extents_cache[slot].is_shared = (ret == 1);
slot = (slot + 1) % BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE;
ctx->prev_extents_cache_slot = slot;
}
if (trans) {
btrfs_put_tree_mod_seq(fs_info, &elem);
btrfs_end_transaction(trans);
} else {
up_read(&fs_info->commit_root_sem);
}
out:
ulist_release(&ctx->refs);
ctx->prev_leaf_bytenr = ctx->curr_leaf_bytenr;
return ret;
}
int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
u64 start_off, struct btrfs_path *path,
struct btrfs_inode_extref **ret_extref,
u64 *found_off)
{
int ret, slot;
struct btrfs_key key;
struct btrfs_key found_key;
struct btrfs_inode_extref *extref;
const struct extent_buffer *leaf;
unsigned long ptr;
key.objectid = inode_objectid;
key.type = BTRFS_INODE_EXTREF_KEY;
key.offset = start_off;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
return ret;
while (1) {
leaf = path->nodes[0];
slot = path->slots[0];
if (slot >= btrfs_header_nritems(leaf)) {
/*
* If the item at offset is not found,
* btrfs_search_slot will point us to the slot
* where it should be inserted. In our case
* that will be the slot directly before the
* next INODE_REF_KEY_V2 item. In the case
* that we're pointing to the last slot in a
* leaf, we must move one leaf over.
*/
ret = btrfs_next_leaf(root, path);
if (ret) {
if (ret >= 1)
ret = -ENOENT;
break;
}
continue;
}
btrfs_item_key_to_cpu(leaf, &found_key, slot);
/*
* Check that we're still looking at an extended ref key for
* this particular objectid. If we have different
* objectid or type then there are no more to be found
* in the tree and we can exit.
*/
ret = -ENOENT;
if (found_key.objectid != inode_objectid)
break;
if (found_key.type != BTRFS_INODE_EXTREF_KEY)
break;
ret = 0;
ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
extref = (struct btrfs_inode_extref *)ptr;
*ret_extref = extref;
if (found_off)
*found_off = found_key.offset;
break;
}
return ret;
}
/*
* this iterates to turn a name (from iref/extref) into a full filesystem path.
* Elements of the path are separated by '/' and the path is guaranteed to be
* 0-terminated. the path is only given within the current file system.
* Therefore, it never starts with a '/'. the caller is responsible to provide
* "size" bytes in "dest". the dest buffer will be filled backwards. finally,
* the start point of the resulting string is returned. this pointer is within
* dest, normally.
* in case the path buffer would overflow, the pointer is decremented further
* as if output was written to the buffer, though no more output is actually
* generated. that way, the caller can determine how much space would be
* required for the path to fit into the buffer. in that case, the returned
* value will be smaller than dest. callers must check this!
*/
char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
u32 name_len, unsigned long name_off,
struct extent_buffer *eb_in, u64 parent,
char *dest, u32 size)
{
int slot;
u64 next_inum;
int ret;
s64 bytes_left = ((s64)size) - 1;
struct extent_buffer *eb = eb_in;
struct btrfs_key found_key;
struct btrfs_inode_ref *iref;
if (bytes_left >= 0)
dest[bytes_left] = '\0';
while (1) {
bytes_left -= name_len;
if (bytes_left >= 0)
read_extent_buffer(eb, dest + bytes_left,
name_off, name_len);
if (eb != eb_in) {
if (!path->skip_locking)
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
}
ret = btrfs_find_item(fs_root, path, parent, 0,
BTRFS_INODE_REF_KEY, &found_key);
if (ret > 0)
ret = -ENOENT;
if (ret)
break;
next_inum = found_key.offset;
/* regular exit ahead */
if (parent == next_inum)
break;
slot = path->slots[0];
eb = path->nodes[0];
/* make sure we can use eb after releasing the path */
if (eb != eb_in) {
path->nodes[0] = NULL;
path->locks[0] = 0;
}
btrfs_release_path(path);
iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
name_len = btrfs_inode_ref_name_len(eb, iref);
name_off = (unsigned long)(iref + 1);
parent = next_inum;
--bytes_left;
if (bytes_left >= 0)
dest[bytes_left] = '/';
}
btrfs_release_path(path);
if (ret)
return ERR_PTR(ret);
return dest + bytes_left;
}
/*
* this makes the path point to (logical EXTENT_ITEM *)
* returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
* tree blocks and <0 on error.
*/
int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
struct btrfs_path *path, struct btrfs_key *found_key,
u64 *flags_ret)
{
struct btrfs_root *extent_root = btrfs_extent_root(fs_info, logical);
int ret;
u64 flags;
u64 size = 0;
u32 item_size;
const struct extent_buffer *eb;
struct btrfs_extent_item *ei;
struct btrfs_key key;
if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
key.type = BTRFS_METADATA_ITEM_KEY;
else
key.type = BTRFS_EXTENT_ITEM_KEY;
key.objectid = logical;
key.offset = (u64)-1;
ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
if (ret < 0)
return ret;
ret = btrfs_previous_extent_item(extent_root, path, 0);
if (ret) {
if (ret > 0)
ret = -ENOENT;
return ret;
}
btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
if (found_key->type == BTRFS_METADATA_ITEM_KEY)
size = fs_info->nodesize;
else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
size = found_key->offset;
if (found_key->objectid > logical ||
found_key->objectid + size <= logical) {
btrfs_debug(fs_info,
"logical %llu is not within any extent", logical);
return -ENOENT;
}
eb = path->nodes[0];
item_size = btrfs_item_size(eb, path->slots[0]);
BUG_ON(item_size < sizeof(*ei));
ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
flags = btrfs_extent_flags(eb, ei);
btrfs_debug(fs_info,
"logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u",
logical, logical - found_key->objectid, found_key->objectid,
found_key->offset, flags, item_size);
WARN_ON(!flags_ret);
if (flags_ret) {
if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
*flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
else if (flags & BTRFS_EXTENT_FLAG_DATA)
*flags_ret = BTRFS_EXTENT_FLAG_DATA;
else
BUG();
return 0;
}
return -EIO;
}
/*
* helper function to iterate extent inline refs. ptr must point to a 0 value
* for the first call and may be modified. it is used to track state.
* if more refs exist, 0 is returned and the next call to
* get_extent_inline_ref must pass the modified ptr parameter to get the
* next ref. after the last ref was processed, 1 is returned.
* returns <0 on error
*/
static int get_extent_inline_ref(unsigned long *ptr,
const struct extent_buffer *eb,
const struct btrfs_key *key,
const struct btrfs_extent_item *ei,
u32 item_size,
struct btrfs_extent_inline_ref **out_eiref,
int *out_type)
{
unsigned long end;
u64 flags;
struct btrfs_tree_block_info *info;
if (!*ptr) {
/* first call */
flags = btrfs_extent_flags(eb, ei);
if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
if (key->type == BTRFS_METADATA_ITEM_KEY) {
/* a skinny metadata extent */
*out_eiref =
(struct btrfs_extent_inline_ref *)(ei + 1);
} else {
WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY);
info = (struct btrfs_tree_block_info *)(ei + 1);
*out_eiref =
(struct btrfs_extent_inline_ref *)(info + 1);
}
} else {
*out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
}
*ptr = (unsigned long)*out_eiref;
if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size)
return -ENOENT;
}
end = (unsigned long)ei + item_size;
*out_eiref = (struct btrfs_extent_inline_ref *)(*ptr);
*out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref,
BTRFS_REF_TYPE_ANY);
if (*out_type == BTRFS_REF_TYPE_INVALID)
return -EUCLEAN;
*ptr += btrfs_extent_inline_ref_size(*out_type);
WARN_ON(*ptr > end);
if (*ptr == end)
return 1; /* last */
return 0;
}
/*
* 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_key *key, struct btrfs_extent_item *ei,
u32 item_size, u64 *out_root, u8 *out_level)
{
int ret;
int type;
struct btrfs_extent_inline_ref *eiref;
if (*ptr == (unsigned long)-1)
return 1;
while (1) {
ret = get_extent_inline_ref(ptr, eb, key, 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 */
*out_root = btrfs_extent_inline_ref_offset(eb, eiref);
if (key->type == BTRFS_EXTENT_ITEM_KEY) {
struct btrfs_tree_block_info *info;
info = (struct btrfs_tree_block_info *)(ei + 1);
*out_level = btrfs_tree_block_level(eb, info);
} else {
ASSERT(key->type == BTRFS_METADATA_ITEM_KEY);
*out_level = (u8)key->offset;
}
if (ret == 1)
*ptr = (unsigned long)-1;
return 0;
}
static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
struct extent_inode_elem *inode_list,
u64 root, u64 extent_item_objectid,
iterate_extent_inodes_t *iterate, void *ctx)
{
struct extent_inode_elem *eie;
int ret = 0;
for (eie = inode_list; eie; eie = eie->next) {
btrfs_debug(fs_info,
"ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu",
extent_item_objectid, eie->inum,
eie->offset, root);
ret = iterate(eie->inum, eie->offset, eie->num_bytes, root, ctx);
if (ret) {
btrfs_debug(fs_info,
"stopping iteration for %llu due to ret=%d",
extent_item_objectid, ret);
break;
}
}
return ret;
}
/*
* calls iterate() for every inode that references the extent identified by
* the given parameters.
* when the iterator function returns a non-zero value, iteration stops.
*/
int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,
bool search_commit_root,
iterate_extent_inodes_t *iterate, void *user_ctx)
{
int ret;
struct ulist *refs;
struct ulist_node *ref_node;
struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem);
struct ulist_iterator ref_uiter;
btrfs_debug(ctx->fs_info, "resolving all inodes for extent %llu",
ctx->bytenr);
ASSERT(ctx->trans == NULL);
ASSERT(ctx->roots == NULL);
if (!search_commit_root) {
struct btrfs_trans_handle *trans;
trans = btrfs_attach_transaction(ctx->fs_info->tree_root);
if (IS_ERR(trans)) {
if (PTR_ERR(trans) != -ENOENT &&
PTR_ERR(trans) != -EROFS)
return PTR_ERR(trans);
trans = NULL;
}
ctx->trans = trans;
}
if (ctx->trans) {
btrfs_get_tree_mod_seq(ctx->fs_info, &seq_elem);
ctx->time_seq = seq_elem.seq;
} else {
down_read(&ctx->fs_info->commit_root_sem);
}
ret = btrfs_find_all_leafs(ctx);
if (ret)
goto out;
refs = ctx->refs;
ctx->refs = NULL;
ULIST_ITER_INIT(&ref_uiter);
while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
const u64 leaf_bytenr = ref_node->val;
struct ulist_node *root_node;
struct ulist_iterator root_uiter;
struct extent_inode_elem *inode_list;
inode_list = (struct extent_inode_elem *)(uintptr_t)ref_node->aux;
if (ctx->cache_lookup) {
const u64 *root_ids;
int root_count;
bool cached;
cached = ctx->cache_lookup(leaf_bytenr, ctx->user_ctx,
&root_ids, &root_count);
if (cached) {
for (int i = 0; i < root_count; i++) {
ret = iterate_leaf_refs(ctx->fs_info,
inode_list,
root_ids[i],
leaf_bytenr,
iterate,
user_ctx);
if (ret)
break;
}
continue;
}
}
if (!ctx->roots) {
ctx->roots = ulist_alloc(GFP_NOFS);
if (!ctx->roots) {
ret = -ENOMEM;
break;
}
}
ctx->bytenr = leaf_bytenr;
ret = btrfs_find_all_roots_safe(ctx);
if (ret)
break;
if (ctx->cache_store)
ctx->cache_store(leaf_bytenr, ctx->roots, ctx->user_ctx);
ULIST_ITER_INIT(&root_uiter);
while (!ret && (root_node = ulist_next(ctx->roots, &root_uiter))) {
btrfs_debug(ctx->fs_info,
"root %llu references leaf %llu, data list %#llx",
root_node->val, ref_node->val,
ref_node->aux);
ret = iterate_leaf_refs(ctx->fs_info, inode_list,
root_node->val, ctx->bytenr,
iterate, user_ctx);
}
ulist_reinit(ctx->roots);
}
free_leaf_list(refs);
out:
if (ctx->trans) {
btrfs_put_tree_mod_seq(ctx->fs_info, &seq_elem);
btrfs_end_transaction(ctx->trans);
ctx->trans = NULL;
} else {
up_read(&ctx->fs_info->commit_root_sem);
}
ulist_free(ctx->roots);
ctx->roots = NULL;
if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP)
ret = 0;
return ret;
}
static int build_ino_list(u64 inum, u64 offset, u64 num_bytes, u64 root, void *ctx)
{
struct btrfs_data_container *inodes = ctx;
const size_t c = 3 * sizeof(u64);
if (inodes->bytes_left >= c) {
inodes->bytes_left -= c;
inodes->val[inodes->elem_cnt] = inum;
inodes->val[inodes->elem_cnt + 1] = offset;
inodes->val[inodes->elem_cnt + 2] = root;
inodes->elem_cnt += 3;
} else {
inodes->bytes_missing += c - inodes->bytes_left;
inodes->bytes_left = 0;
inodes->elem_missed += 3;
}
return 0;
}
int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
void *ctx, bool ignore_offset)
{
struct btrfs_backref_walk_ctx walk_ctx = { 0 };
int ret;
u64 flags = 0;
struct btrfs_key found_key;
int search_commit_root = path->search_commit_root;
ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
btrfs_release_path(path);
if (ret < 0)
return ret;
if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
return -EINVAL;
walk_ctx.bytenr = found_key.objectid;
if (ignore_offset)
walk_ctx.ignore_extent_item_pos = true;
else
walk_ctx.extent_item_pos = logical - found_key.objectid;
walk_ctx.fs_info = fs_info;
return iterate_extent_inodes(&walk_ctx, search_commit_root,
build_ino_list, ctx);
}
static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
struct extent_buffer *eb, struct inode_fs_paths *ipath);
static int iterate_inode_refs(u64 inum, struct inode_fs_paths *ipath)
{
int ret = 0;
int slot;
u32 cur;
u32 len;
u32 name_len;
u64 parent = 0;
int found = 0;
struct btrfs_root *fs_root = ipath->fs_root;
struct btrfs_path *path = ipath->btrfs_path;
struct extent_buffer *eb;
struct btrfs_inode_ref *iref;
struct btrfs_key found_key;
while (!ret) {
ret = btrfs_find_item(fs_root, path, inum,
parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY,
&found_key);
if (ret < 0)
break;
if (ret) {
ret = found ? 0 : -ENOENT;
break;
}
++found;
parent = found_key.offset;
slot = path->slots[0];
eb = btrfs_clone_extent_buffer(path->nodes[0]);
if (!eb) {
ret = -ENOMEM;
break;
}
btrfs_release_path(path);
iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
for (cur = 0; cur < btrfs_item_size(eb, slot); cur += len) {
name_len = btrfs_inode_ref_name_len(eb, iref);
/* path must be released before calling iterate()! */
btrfs_debug(fs_root->fs_info,
"following ref at offset %u for inode %llu in tree %llu",
cur, found_key.objectid,
fs_root->root_key.objectid);
ret = inode_to_path(parent, name_len,
(unsigned long)(iref + 1), eb, ipath);
if (ret)
break;
len = sizeof(*iref) + name_len;
iref = (struct btrfs_inode_ref *)((char *)iref + len);
}
free_extent_buffer(eb);
}
btrfs_release_path(path);
return ret;
}
static int iterate_inode_extrefs(u64 inum, struct inode_fs_paths *ipath)
{
int ret;
int slot;
u64 offset = 0;
u64 parent;
int found = 0;
struct btrfs_root *fs_root = ipath->fs_root;
struct btrfs_path *path = ipath->btrfs_path;
struct extent_buffer *eb;
struct btrfs_inode_extref *extref;
u32 item_size;
u32 cur_offset;
unsigned long ptr;
while (1) {
ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
&offset);
if (ret < 0)
break;
if (ret) {
ret = found ? 0 : -ENOENT;
break;
}
++found;
slot = path->slots[0];
eb = btrfs_clone_extent_buffer(path->nodes[0]);
if (!eb) {
ret = -ENOMEM;
break;
}
btrfs_release_path(path);
item_size = btrfs_item_size(eb, slot);
ptr = btrfs_item_ptr_offset(eb, slot);
cur_offset = 0;
while (cur_offset < item_size) {
u32 name_len;
extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
parent = btrfs_inode_extref_parent(eb, extref);
name_len = btrfs_inode_extref_name_len(eb, extref);
ret = inode_to_path(parent, name_len,
(unsigned long)&extref->name, eb, ipath);
if (ret)
break;
cur_offset += btrfs_inode_extref_name_len(eb, extref);
cur_offset += sizeof(*extref);
}
free_extent_buffer(eb);
offset++;
}
btrfs_release_path(path);
return ret;
}
/*
* returns 0 if the path could be dumped (probably truncated)
* returns <0 in case of an error
*/
static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
struct extent_buffer *eb, struct inode_fs_paths *ipath)
{
char *fspath;
char *fspath_min;
int i = ipath->fspath->elem_cnt;
const int s_ptr = sizeof(char *);
u32 bytes_left;
bytes_left = ipath->fspath->bytes_left > s_ptr ?
ipath->fspath->bytes_left - s_ptr : 0;
fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
name_off, eb, inum, fspath_min, bytes_left);
if (IS_ERR(fspath))
return PTR_ERR(fspath);
if (fspath > fspath_min) {
ipath->fspath->val[i] = (u64)(unsigned long)fspath;
++ipath->fspath->elem_cnt;
ipath->fspath->bytes_left = fspath - fspath_min;
} else {
++ipath->fspath->elem_missed;
ipath->fspath->bytes_missing += fspath_min - fspath;
ipath->fspath->bytes_left = 0;
}
return 0;
}
/*
* this dumps all file system paths to the inode into the ipath struct, provided
* is has been created large enough. each path is zero-terminated and accessed
* from ipath->fspath->val[i].
* when it returns, there are ipath->fspath->elem_cnt number of paths available
* in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
* number of missed paths is recorded in ipath->fspath->elem_missed, otherwise,
* it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
* have been needed to return all paths.
*/
int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
{
int ret;
int found_refs = 0;
ret = iterate_inode_refs(inum, ipath);
if (!ret)
++found_refs;
else if (ret != -ENOENT)
return ret;
ret = iterate_inode_extrefs(inum, ipath);
if (ret == -ENOENT && found_refs)
return 0;
return ret;
}
struct btrfs_data_container *init_data_container(u32 total_bytes)
{
struct btrfs_data_container *data;
size_t alloc_bytes;
alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
data = kvmalloc(alloc_bytes, GFP_KERNEL);
if (!data)
return ERR_PTR(-ENOMEM);
if (total_bytes >= sizeof(*data)) {
data->bytes_left = total_bytes - sizeof(*data);
data->bytes_missing = 0;
} else {
data->bytes_missing = sizeof(*data) - total_bytes;
data->bytes_left = 0;
}
data->elem_cnt = 0;
data->elem_missed = 0;
return data;
}
/*
* allocates space to return multiple file system paths for an inode.
* total_bytes to allocate are passed, note that space usable for actual path
* information will be total_bytes - sizeof(struct inode_fs_paths).
* the returned pointer must be freed with free_ipath() in the end.
*/
struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
struct btrfs_path *path)
{
struct inode_fs_paths *ifp;
struct btrfs_data_container *fspath;
fspath = init_data_container(total_bytes);
if (IS_ERR(fspath))
return ERR_CAST(fspath);
ifp = kmalloc(sizeof(*ifp), GFP_KERNEL);
if (!ifp) {
kvfree(fspath);
return ERR_PTR(-ENOMEM);
}
ifp->btrfs_path = path;
ifp->fspath = fspath;
ifp->fs_root = fs_root;
return ifp;
}
void free_ipath(struct inode_fs_paths *ipath)
{
if (!ipath)
return;
kvfree(ipath->fspath);
kfree(ipath);
}
struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info)
{
struct btrfs_backref_iter *ret;
ret = kzalloc(sizeof(*ret), GFP_NOFS);
if (!ret)
return NULL;
ret->path = btrfs_alloc_path();
if (!ret->path) {
kfree(ret);
return NULL;
}
/* Current backref iterator only supports iteration in commit root */
ret->path->search_commit_root = 1;
ret->path->skip_locking = 1;
ret->fs_info = fs_info;
return ret;
}
int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
{
struct btrfs_fs_info *fs_info = iter->fs_info;
struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr);
struct btrfs_path *path = iter->path;
struct btrfs_extent_item *ei;
struct btrfs_key key;
int ret;
key.objectid = bytenr;
key.type = BTRFS_METADATA_ITEM_KEY;
key.offset = (u64)-1;
iter->bytenr = bytenr;
ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
if (ret < 0)
return ret;
if (ret == 0) {
ret = -EUCLEAN;
goto release;
}
if (path->slots[0] == 0) {
WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
ret = -EUCLEAN;
goto release;
}
path->slots[0]--;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if ((key.type != BTRFS_EXTENT_ITEM_KEY &&
key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) {
ret = -ENOENT;
goto release;
}
memcpy(&iter->cur_key, &key, sizeof(key));
iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
path->slots[0]);
iter->end_ptr = (u32)(iter->item_ptr +
btrfs_item_size(path->nodes[0], path->slots[0]));
ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_extent_item);
/*
* Only support iteration on tree backref yet.
*
* This is an extra precaution for non skinny-metadata, where
* EXTENT_ITEM is also used for tree blocks, that we can only use
* extent flags to determine if it's a tree block.
*/
if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) {
ret = -ENOTSUPP;
goto release;
}
iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei));
/* If there is no inline backref, go search for keyed backref */
if (iter->cur_ptr >= iter->end_ptr) {
ret = btrfs_next_item(extent_root, path);
/* No inline nor keyed ref */
if (ret > 0) {
ret = -ENOENT;
goto release;
}
if (ret < 0)
goto release;
btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key,
path->slots[0]);
if (iter->cur_key.objectid != bytenr ||
(iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY &&
iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) {
ret = -ENOENT;
goto release;
}
iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
path->slots[0]);
iter->item_ptr = iter->cur_ptr;
iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size(
path->nodes[0], path->slots[0]));
}
return 0;
release:
btrfs_backref_iter_release(iter);
return ret;
}
/*
* Go to the next backref item of current bytenr, can be either inlined or
* keyed.
*
* Caller needs to check whether it's inline ref or not by iter->cur_key.
*
* Return 0 if we get next backref without problem.
* Return >0 if there is no extra backref for this bytenr.
* Return <0 if there is something wrong happened.
*/
int btrfs_backref_iter_next(struct btrfs_backref_iter *iter)
{
struct extent_buffer *eb = btrfs_backref_get_eb(iter);
struct btrfs_root *extent_root;
struct btrfs_path *path = iter->path;
struct btrfs_extent_inline_ref *iref;
int ret;
u32 size;
if (btrfs_backref_iter_is_inline_ref(iter)) {
/* We're still inside the inline refs */
ASSERT(iter->cur_ptr < iter->end_ptr);
if (btrfs_backref_has_tree_block_info(iter)) {
/* First tree block info */
size = sizeof(struct btrfs_tree_block_info);
} else {
/* Use inline ref type to determine the size */
int type;
iref = (struct btrfs_extent_inline_ref *)
((unsigned long)iter->cur_ptr);
type = btrfs_extent_inline_ref_type(eb, iref);
size = btrfs_extent_inline_ref_size(type);
}
iter->cur_ptr += size;
if (iter->cur_ptr < iter->end_ptr)
return 0;
/* All inline items iterated, fall through */
}
/* We're at keyed items, there is no inline item, go to the next one */
extent_root = btrfs_extent_root(iter->fs_info, iter->bytenr);
ret = btrfs_next_item(extent_root, iter->path);
if (ret)
return ret;
btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]);
if (iter->cur_key.objectid != iter->bytenr ||
(iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY &&
iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY))
return 1;
iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0],
path->slots[0]);
iter->cur_ptr = iter->item_ptr;
iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size(path->nodes[0],
path->slots[0]);
return 0;
}
void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
struct btrfs_backref_cache *cache, int is_reloc)
{
int i;
cache->rb_root = RB_ROOT;
for (i = 0; i < BTRFS_MAX_LEVEL; i++)
INIT_LIST_HEAD(&cache->pending[i]);
INIT_LIST_HEAD(&cache->changed);
INIT_LIST_HEAD(&cache->detached);
INIT_LIST_HEAD(&cache->leaves);
INIT_LIST_HEAD(&cache->pending_edge);
INIT_LIST_HEAD(&cache->useless_node);
cache->fs_info = fs_info;
cache->is_reloc = is_reloc;
}
struct btrfs_backref_node *btrfs_backref_alloc_node(
struct btrfs_backref_cache *cache, u64 bytenr, int level)
{
struct btrfs_backref_node *node;
ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL);
node = kzalloc(sizeof(*node), GFP_NOFS);
if (!node)
return node;
INIT_LIST_HEAD(&node->list);
INIT_LIST_HEAD(&node->upper);
INIT_LIST_HEAD(&node->lower);
RB_CLEAR_NODE(&node->rb_node);
cache->nr_nodes++;
node->level = level;
node->bytenr = bytenr;
return node;
}
struct btrfs_backref_edge *btrfs_backref_alloc_edge(
struct btrfs_backref_cache *cache)
{
struct btrfs_backref_edge *edge;
edge = kzalloc(sizeof(*edge), GFP_NOFS);
if (edge)
cache->nr_edges++;
return edge;
}
/*
* Drop the backref node from cache, also cleaning up all its
* upper edges and any uncached nodes in the path.
*
* This cleanup happens bottom up, thus the node should either
* be the lowest node in the cache or a detached node.
*/
void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *node)
{
struct btrfs_backref_node *upper;
struct btrfs_backref_edge *edge;
if (!node)
return;
BUG_ON(!node->lowest && !node->detached);
while (!list_empty(&node->upper)) {
edge = list_entry(node->upper.next, struct btrfs_backref_edge,
list[LOWER]);
upper = edge->node[UPPER];
list_del(&edge->list[LOWER]);
list_del(&edge->list[UPPER]);
btrfs_backref_free_edge(cache, edge);
/*
* Add the node to leaf node list if no other child block
* cached.
*/
if (list_empty(&upper->lower)) {
list_add_tail(&upper->lower, &cache->leaves);
upper->lowest = 1;
}
}
btrfs_backref_drop_node(cache, node);
}
/*
* Release all nodes/edges from current cache
*/
void btrfs_backref_release_cache(struct btrfs_backref_cache *cache)
{
struct btrfs_backref_node *node;
int i;
while (!list_empty(&cache->detached)) {
node = list_entry(cache->detached.next,
struct btrfs_backref_node, list);
btrfs_backref_cleanup_node(cache, node);
}
while (!list_empty(&cache->leaves)) {
node = list_entry(cache->leaves.next,
struct btrfs_backref_node, lower);
btrfs_backref_cleanup_node(cache, node);
}
cache->last_trans = 0;
for (i = 0; i < BTRFS_MAX_LEVEL; i++)
ASSERT(list_empty(&cache->pending[i]));
ASSERT(list_empty(&cache->pending_edge));
ASSERT(list_empty(&cache->useless_node));
ASSERT(list_empty(&cache->changed));
ASSERT(list_empty(&cache->detached));
ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
ASSERT(!cache->nr_nodes);
ASSERT(!cache->nr_edges);
}
/*
* Handle direct tree backref
*
* Direct tree backref means, the backref item shows its parent bytenr
* directly. This is for SHARED_BLOCK_REF backref (keyed or inlined).
*
* @ref_key: The converted backref key.
* For keyed backref, it's the item key.
* For inlined backref, objectid is the bytenr,
* type is btrfs_inline_ref_type, offset is
* btrfs_inline_ref_offset.
*/
static int handle_direct_tree_backref(struct btrfs_backref_cache *cache,
struct btrfs_key *ref_key,
struct btrfs_backref_node *cur)
{
struct btrfs_backref_edge *edge;
struct btrfs_backref_node *upper;
struct rb_node *rb_node;
ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY);
/* Only reloc root uses backref pointing to itself */
if (ref_key->objectid == ref_key->offset) {
struct btrfs_root *root;
cur->is_reloc_root = 1;
/* Only reloc backref cache cares about a specific root */
if (cache->is_reloc) {
root = find_reloc_root(cache->fs_info, cur->bytenr);
if (!root)
return -ENOENT;
cur->root = root;
} else {
/*
* For generic purpose backref cache, reloc root node
* is useless.
*/
list_add(&cur->list, &cache->useless_node);
}
return 0;
}
edge = btrfs_backref_alloc_edge(cache);
if (!edge)
return -ENOMEM;
rb_node = rb_simple_search(&cache->rb_root, ref_key->offset);
if (!rb_node) {
/* Parent node not yet cached */
upper = btrfs_backref_alloc_node(cache, ref_key->offset,
cur->level + 1);
if (!upper) {
btrfs_backref_free_edge(cache, edge);
return -ENOMEM;
}
/*
* Backrefs for the upper level block isn't cached, add the
* block to pending list
*/
list_add_tail(&edge->list[UPPER], &cache->pending_edge);
} else {
/* Parent node already cached */
upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
ASSERT(upper->checked);
INIT_LIST_HEAD(&edge->list[UPPER]);
}
btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
return 0;
}
/*
* Handle indirect tree backref
*
* Indirect tree backref means, we only know which tree the node belongs to.
* We still need to do a tree search to find out the parents. This is for
* TREE_BLOCK_REF backref (keyed or inlined).
*
* @ref_key: The same as @ref_key in handle_direct_tree_backref()
* @tree_key: The first key of this tree block.
* @path: A clean (released) path, to avoid allocating path every time
* the function get called.
*/
static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache,
struct btrfs_path *path,
struct btrfs_key *ref_key,
struct btrfs_key *tree_key,
struct btrfs_backref_node *cur)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
struct btrfs_backref_node *upper;
struct btrfs_backref_node *lower;
struct btrfs_backref_edge *edge;
struct extent_buffer *eb;
struct btrfs_root *root;
struct rb_node *rb_node;
int level;
bool need_check = true;
int ret;
root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
if (IS_ERR(root))
return PTR_ERR(root);
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
cur->cowonly = 1;
if (btrfs_root_level(&root->root_item) == cur->level) {
/* Tree root */
ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr);
/*
* For reloc backref cache, we may ignore reloc root. But for
* general purpose backref cache, we can't rely on
* btrfs_should_ignore_reloc_root() as it may conflict with
* current running relocation and lead to missing root.
*
* For general purpose backref cache, reloc root detection is
* completely relying on direct backref (key->offset is parent
* bytenr), thus only do such check for reloc cache.
*/
if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) {
btrfs_put_root(root);
list_add(&cur->list, &cache->useless_node);
} else {
cur->root = root;
}
return 0;
}
level = cur->level + 1;
/* Search the tree to find parent blocks referring to the block */
path->search_commit_root = 1;
path->skip_locking = 1;
path->lowest_level = level;
ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0);
path->lowest_level = 0;
if (ret < 0) {
btrfs_put_root(root);
return ret;
}
if (ret > 0 && path->slots[level] > 0)
path->slots[level]--;
eb = path->nodes[level];
if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) {
btrfs_err(fs_info,
"couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
cur->bytenr, level - 1, root->root_key.objectid,
tree_key->objectid, tree_key->type, tree_key->offset);
btrfs_put_root(root);
ret = -ENOENT;
goto out;
}
lower = cur;
/* Add all nodes and edges in the path */
for (; level < BTRFS_MAX_LEVEL; level++) {
if (!path->nodes[level]) {
ASSERT(btrfs_root_bytenr(&root->root_item) ==
lower->bytenr);
/* Same as previous should_ignore_reloc_root() call */
if (btrfs_should_ignore_reloc_root(root) &&
cache->is_reloc) {
btrfs_put_root(root);
list_add(&lower->list, &cache->useless_node);
} else {
lower->root = root;
}
break;
}
edge = btrfs_backref_alloc_edge(cache);
if (!edge) {
btrfs_put_root(root);
ret = -ENOMEM;
goto out;
}
eb = path->nodes[level];
rb_node = rb_simple_search(&cache->rb_root, eb->start);
if (!rb_node) {
upper = btrfs_backref_alloc_node(cache, eb->start,
lower->level + 1);
if (!upper) {
btrfs_put_root(root);
btrfs_backref_free_edge(cache, edge);
ret = -ENOMEM;
goto out;
}
upper->owner = btrfs_header_owner(eb);
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
upper->cowonly = 1;
/*
* If we know the block isn't shared we can avoid
* checking its backrefs.
*/
if (btrfs_block_can_be_shared(root, eb))
upper->checked = 0;
else
upper->checked = 1;
/*
* Add the block to pending list if we need to check its
* backrefs, we only do this once while walking up a
* tree as we will catch anything else later on.
*/
if (!upper->checked && need_check) {
need_check = false;
list_add_tail(&edge->list[UPPER],
&cache->pending_edge);
} else {
if (upper->checked)
need_check = true;
INIT_LIST_HEAD(&edge->list[UPPER]);
}
} else {
upper = rb_entry(rb_node, struct btrfs_backref_node,
rb_node);
ASSERT(upper->checked);
INIT_LIST_HEAD(&edge->list[UPPER]);
if (!upper->owner)
upper->owner = btrfs_header_owner(eb);
}
btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
if (rb_node) {
btrfs_put_root(root);
break;
}
lower = upper;
upper = NULL;
}
out:
btrfs_release_path(path);
return ret;
}
/*
* Add backref node @cur into @cache.
*
* NOTE: Even if the function returned 0, @cur is not yet cached as its upper
* links aren't yet bi-directional. Needs to finish such links.
* Use btrfs_backref_finish_upper_links() to finish such linkage.
*
* @path: Released path for indirect tree backref lookup
* @iter: Released backref iter for extent tree search
* @node_key: The first key of the tree block
*/
int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
struct btrfs_path *path,
struct btrfs_backref_iter *iter,
struct btrfs_key *node_key,
struct btrfs_backref_node *cur)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
struct btrfs_backref_edge *edge;
struct btrfs_backref_node *exist;
int ret;
ret = btrfs_backref_iter_start(iter, cur->bytenr);
if (ret < 0)
return ret;
/*
* We skip the first btrfs_tree_block_info, as we don't use the key
* stored in it, but fetch it from the tree block
*/
if (btrfs_backref_has_tree_block_info(iter)) {
ret = btrfs_backref_iter_next(iter);
if (ret < 0)
goto out;
/* No extra backref? This means the tree block is corrupted */
if (ret > 0) {
ret = -EUCLEAN;
goto out;
}
}
WARN_ON(cur->checked);
if (!list_empty(&cur->upper)) {
/*
* The backref was added previously when processing backref of
* type BTRFS_TREE_BLOCK_REF_KEY
*/
ASSERT(list_is_singular(&cur->upper));
edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
list[LOWER]);
ASSERT(list_empty(&edge->list[UPPER]));
exist = edge->node[UPPER];
/*
* Add the upper level block to pending list if we need check
* its backrefs
*/
if (!exist->checked)
list_add_tail(&edge->list[UPPER], &cache->pending_edge);
} else {
exist = NULL;
}
for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
struct extent_buffer *eb;
struct btrfs_key key;
int type;
cond_resched();
eb = btrfs_backref_get_eb(iter);
key.objectid = iter->bytenr;
if (btrfs_backref_iter_is_inline_ref(iter)) {
struct btrfs_extent_inline_ref *iref;
/* Update key for inline backref */
iref = (struct btrfs_extent_inline_ref *)
((unsigned long)iter->cur_ptr);
type = btrfs_get_extent_inline_ref_type(eb, iref,
BTRFS_REF_TYPE_BLOCK);
if (type == BTRFS_REF_TYPE_INVALID) {
ret = -EUCLEAN;
goto out;
}
key.type = type;
key.offset = btrfs_extent_inline_ref_offset(eb, iref);
} else {
key.type = iter->cur_key.type;
key.offset = iter->cur_key.offset;
}
/*
* Parent node found and matches current inline ref, no need to
* rebuild this node for this inline ref
*/
if (exist &&
((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
exist->owner == key.offset) ||
(key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
exist->bytenr == key.offset))) {
exist = NULL;
continue;
}
/* SHARED_BLOCK_REF means key.offset is the parent bytenr */
if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
ret = handle_direct_tree_backref(cache, &key, cur);
if (ret < 0)
goto out;
continue;
} else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
ret = -EINVAL;
btrfs_print_v0_err(fs_info);
btrfs_handle_fs_error(fs_info, ret, NULL);
goto out;
} else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
continue;
}
/*
* key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
* means the root objectid. We need to search the tree to get
* its parent bytenr.
*/
ret = handle_indirect_tree_backref(cache, path, &key, node_key,
cur);
if (ret < 0)
goto out;
}
ret = 0;
cur->checked = 1;
WARN_ON(exist);
out:
btrfs_backref_iter_release(iter);
return ret;
}
/*
* Finish the upwards linkage created by btrfs_backref_add_tree_node()
*/
int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *start)
{
struct list_head *useless_node = &cache->useless_node;
struct btrfs_backref_edge *edge;
struct rb_node *rb_node;
LIST_HEAD(pending_edge);
ASSERT(start->checked);
/* Insert this node to cache if it's not COW-only */
if (!start->cowonly) {
rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
&start->rb_node);
if (rb_node)
btrfs_backref_panic(cache->fs_info, start->bytenr,
-EEXIST);
list_add_tail(&start->lower, &cache->leaves);
}
/*
* Use breadth first search to iterate all related edges.
*
* The starting points are all the edges of this node
*/
list_for_each_entry(edge, &start->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &pending_edge);
while (!list_empty(&pending_edge)) {
struct btrfs_backref_node *upper;
struct btrfs_backref_node *lower;
edge = list_first_entry(&pending_edge,
struct btrfs_backref_edge, list[UPPER]);
list_del_init(&edge->list[UPPER]);
upper = edge->node[UPPER];
lower = edge->node[LOWER];
/* Parent is detached, no need to keep any edges */
if (upper->detached) {
list_del(&edge->list[LOWER]);
btrfs_backref_free_edge(cache, edge);
/* Lower node is orphan, queue for cleanup */
if (list_empty(&lower->upper))
list_add(&lower->list, useless_node);
continue;
}
/*
* All new nodes added in current build_backref_tree() haven't
* been linked to the cache rb tree.
* So if we have upper->rb_node populated, this means a cache
* hit. We only need to link the edge, as @upper and all its
* parents have already been linked.
*/
if (!RB_EMPTY_NODE(&upper->rb_node)) {
if (upper->lowest) {
list_del_init(&upper->lower);
upper->lowest = 0;
}
list_add_tail(&edge->list[UPPER], &upper->lower);
continue;
}
/* Sanity check, we shouldn't have any unchecked nodes */
if (!upper->checked) {
ASSERT(0);
return -EUCLEAN;
}
/* Sanity check, COW-only node has non-COW-only parent */
if (start->cowonly != upper->cowonly) {
ASSERT(0);
return -EUCLEAN;
}
/* Only cache non-COW-only (subvolume trees) tree blocks */
if (!upper->cowonly) {
rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
&upper->rb_node);
if (rb_node) {
btrfs_backref_panic(cache->fs_info,
upper->bytenr, -EEXIST);
return -EUCLEAN;
}
}
list_add_tail(&edge->list[UPPER], &upper->lower);
/*
* Also queue all the parent edges of this uncached node
* to finish the upper linkage
*/
list_for_each_entry(edge, &upper->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &pending_edge);
}
return 0;
}
void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *node)
{
struct btrfs_backref_node *lower;
struct btrfs_backref_node *upper;
struct btrfs_backref_edge *edge;
while (!list_empty(&cache->useless_node)) {
lower = list_first_entry(&cache->useless_node,
struct btrfs_backref_node, list);
list_del_init(&lower->list);
}
while (!list_empty(&cache->pending_edge)) {
edge = list_first_entry(&cache->pending_edge,
struct btrfs_backref_edge, list[UPPER]);
list_del(&edge->list[UPPER]);
list_del(&edge->list[LOWER]);
lower = edge->node[LOWER];
upper = edge->node[UPPER];
btrfs_backref_free_edge(cache, edge);
/*
* Lower is no longer linked to any upper backref nodes and
* isn't in the cache, we can free it ourselves.
*/
if (list_empty(&lower->upper) &&
RB_EMPTY_NODE(&lower->rb_node))
list_add(&lower->list, &cache->useless_node);
if (!RB_EMPTY_NODE(&upper->rb_node))
continue;
/* Add this guy's upper edges to the list to process */
list_for_each_entry(edge, &upper->upper, list[LOWER])
list_add_tail(&edge->list[UPPER],
&cache->pending_edge);
if (list_empty(&upper->upper))
list_add(&upper->list, &cache->useless_node);
}
while (!list_empty(&cache->useless_node)) {
lower = list_first_entry(&cache->useless_node,
struct btrfs_backref_node, list);
list_del_init(&lower->list);
if (lower == node)
node = NULL;
btrfs_backref_drop_node(cache, lower);
}
btrfs_backref_cleanup_node(cache, node);
ASSERT(list_empty(&cache->useless_node) &&
list_empty(&cache->pending_edge));
}
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