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linux/fs/btrfs/backref.c
Filipe Manana 765f828902 btrfs: pass fs_info to functions that search for delayed ref heads 
One of the following patches in the series will need to access fs_info in
the function find_ref_head(), so pass a fs_info argument to it as well as
to the functions btrfs_select_ref_head() and btrfs_find_delayed_ref_head()
which call find_ref_head().

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:20 +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"
#include "tree-checker.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 (!ctx->ignore_extent_item_pos &&
!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, 0, 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(const struct prelim_ref *ref1,
const 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, const 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 == btrfs_root_id(sc->root) &&
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;
u8 type;
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);
type = btrfs_file_extent_type(eb, fi);
if (type == BTRFS_FILE_EXTENT_INLINE)
goto next;
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->skip_inode_ref_list) {
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->skip_inode_ref_list) {
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 != btrfs_root_id(sc->root)) {
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_key *key_ptr = NULL;
/* The owner of a tree block ref is the level. */
int level = btrfs_delayed_ref_owner(node);
if (head->extent_op && head->extent_op->update_key) {
btrfs_disk_key_to_cpu(&key, &head->extent_op->key);
key_ptr = &key;
}
ret = add_indirect_ref(fs_info, preftrees, node->ref_root,
key_ptr, level + 1, node->bytenr,
count, sc, GFP_ATOMIC);
break;
}
case BTRFS_SHARED_BLOCK_REF_KEY: {
/*
* SHARED DIRECT METADATA backref
*
* The owner of a tree block ref is the level.
*/
int level = btrfs_delayed_ref_owner(node);
ret = add_direct_ref(fs_info, preftrees, level + 1,
node->parent, node->bytenr, count,
sc, GFP_ATOMIC);
break;
}
case BTRFS_EXTENT_DATA_REF_KEY: {
/* NORMAL INDIRECT DATA backref */
key.objectid = btrfs_delayed_ref_owner(node);
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = btrfs_delayed_ref_offset(node);
/*
* 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, node->ref_root,
&key, 0, node->bytenr, count, sc,
GFP_ATOMIC);
break;
}
case BTRFS_SHARED_DATA_REF_KEY: {
/* SHARED DIRECT FULL backref */
ret = add_direct_ref(fs_info, preftrees, 0, node->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);
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;
}
case BTRFS_EXTENT_OWNER_REF_KEY:
ASSERT(btrfs_fs_incompat(ctx->fs_info, SIMPLE_QUOTA));
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)
{
const struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_backref_shared_cache_entry *entry;
if (!current->journal_info)
lockdep_assert_held(&fs_info->commit_root_sem);
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(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)
{
const struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_backref_shared_cache_entry *entry;
u64 gen;
if (!current->journal_info)
lockdep_assert_held(&fs_info->commit_root_sem);
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(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) {
/*
* Key with offset -1 found, there would have to exist an extent
* item with such offset, but this is out of the valid range.
*/
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(ctx->fs_info, 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->skip_inode_ref_list && !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->skip_inode_ref_list) {
/*
* 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_skip_inode_ref_list = ctx->skip_inode_ref_list;
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->skip_inode_ref_list = 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->skip_inode_ref_list = orig_skip_inode_ref_list;
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;
bool leaf_cached;
bool leaf_is_shared;
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;
}
ctx->use_path_cache = true;
/*
* We may have previously determined that the current leaf is shared.
* If it is, then we have a data extent that is shared due to a shared
* subtree (caused by snapshotting) and we don't need to check for data
* backrefs. If the leaf is not shared, then we must do backref walking
* to determine if the data extent is shared through reflinks.
*/
leaf_cached = lookup_backref_shared_cache(ctx, root,
ctx->curr_leaf_bytenr, 0,
&leaf_is_shared);
if (leaf_cached && leaf_is_shared) {
ret = 1;
goto out_trans;
}
walk_ctx.skip_inode_ref_list = 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);
while (1) {
const unsigned long prev_ref_count = ctx->refs.nnodes;
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;
/*
* More than one extent buffer (bytenr) may have been added to
* the ctx->refs ulist, in which case we have to check multiple
* tree paths in case the first one is not shared, so we can not
* use the path cache which is made for a single path. Multiple
* extent buffers at the current level happen when:
*
* 1) level -1, the data extent: If our data extent was not
* directly shared (without multiple reference items), then
* 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).
*
* 2) level >= 0, a tree node/leaf: We can have a mix of direct
* and indirect references on a b+tree node/leaf, so we have
* to check multiple paths, and the extent buffer (the
* current bytenr) may be shared or not. One example is
* during relocation as we may get a shared tree block ref
* (direct ref) and a non-shared tree block ref (indirect
* ref) for the same node/leaf.
*/
if ((ctx->refs.nnodes - prev_ref_count) > 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;
if (ctx->use_path_cache) {
bool is_shared;
bool cached;
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();
}
/*
* If the path cache is disabled, then it means at some tree level we
* got multiple parents due to a mix of direct and indirect backrefs or
* multiple leaves with file extent items pointing to the same data
* extent. We have to invalidate the cache and cache only the sharedness
* result for the levels where we got only one node/reference.
*/
if (!ctx->use_path_cache) {
int i = 0;
level--;
if (ret >= 0 && level >= 0) {
bytenr = ctx->path_cache_entries[level].bytenr;
ctx->use_path_cache = true;
store_backref_shared_cache(ctx, root, bytenr, level, ret);
i = level + 1;
}
for ( ; i < BTRFS_MAX_LEVEL; i++)
ctx->path_cache_entries[i].bytenr = 0;
}
/*
* 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;
}
out_trans:
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;
if (ret == 0) {
/*
* Key with offset -1 found, there would have to exist an extent
* item with such offset, but this is out of the valid range.
*/
return -EUCLEAN;
}
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]);
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,
btrfs_root_id(fs_root));
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 = kvzalloc(alloc_bytes, GFP_KERNEL);
if (!data)
return ERR_PTR(-ENOMEM);
if (total_bytes >= sizeof(*data))
data->bytes_left = total_bytes - sizeof(*data);
else
data->bytes_missing = sizeof(*data) - total_bytes;
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;
}
static void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
{
iter->bytenr = 0;
iter->item_ptr = 0;
iter->cur_ptr = 0;
iter->end_ptr = 0;
btrfs_release_path(iter->path);
memset(&iter->cur_key, 0, sizeof(iter->cur_key));
}
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) {
/*
* Key with offset -1 found, there would have to exist an extent
* item with such offset, but this is out of the valid range.
*/
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;
}
static bool btrfs_backref_iter_is_inline_ref(struct btrfs_backref_iter *iter)
{
if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
return true;
return false;
}
/*
* 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 = iter->path->nodes[0];
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, bool 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;
}
void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *node)
{
if (node) {
ASSERT(list_empty(&node->list));
ASSERT(list_empty(&node->lower));
ASSERT(node->eb == NULL);
cache->nr_nodes--;
btrfs_put_root(node->root);
kfree(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;
}
void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
struct btrfs_backref_edge *edge)
{
if (edge) {
cache->nr_edges--;
kfree(edge);
}
}
void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node)
{
if (node->locked) {
btrfs_tree_unlock(node->eb);
node->locked = 0;
}
}
void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node)
{
if (node->eb) {
btrfs_backref_unlock_node_buffer(node);
free_extent_buffer(node->eb);
node->eb = NULL;
}
}
/*
* Drop the backref node from cache without cleaning up its children
* edges.
*
* This can only be called on node without parent edges.
* The children edges are still kept as is.
*/
void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
struct btrfs_backref_node *node)
{
ASSERT(list_empty(&node->upper));
btrfs_backref_drop_node_buffer(node);
list_del_init(&node->list);
list_del_init(&node->lower);
if (!RB_EMPTY_NODE(&node->rb_node))
rb_erase(&node->rb_node, &tree->rb_root);
btrfs_backref_free_node(tree, node);
}
/*
* 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);
}
for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
while (!list_empty(&cache->pending[i])) {
node = list_first_entry(&cache->pending[i],
struct btrfs_backref_node,
list);
btrfs_backref_cleanup_node(cache, node);
}
}
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);
}
void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
struct btrfs_backref_node *lower,
struct btrfs_backref_node *upper,
int link_which)
{
ASSERT(upper && lower && upper->level == lower->level + 1);
edge->node[LOWER] = lower;
edge->node[UPPER] = upper;
if (link_which & LINK_LOWER)
list_add_tail(&edge->list[LOWER], &lower->upper);
if (link_which & LINK_UPPER)
list_add_tail(&edge->list[UPPER], &upper->lower);
}
/*
* 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).
*
* @trans: Transaction handle.
* @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_trans_handle *trans,
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, btrfs_root_id(root),
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(trans, 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.
*
* @trans: Transaction handle.
* @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_trans_handle *trans,
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_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 = iter->path->nodes[0];
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;
} else if (key.type == BTRFS_TREE_BLOCK_REF_KEY) {
/*
* 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(trans, cache, path,
&key, node_key, cur);
if (ret < 0)
goto out;
}
/*
* Unrecognized tree backref items (if it can pass tree-checker)
* would be ignored.
*/
}
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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