linux/fs/btrfs/delayed-ref.c
Filipe Manana 8949b9a114 btrfs: fix lock inversion problem when doing qgroup extent tracing
At btrfs_qgroup_trace_extent_post() we call btrfs_find_all_roots() with a
NULL value as the transaction handle argument, which makes that function
take the commit_root_sem semaphore, which is necessary when we don't hold
a transaction handle or any other mechanism to prevent a transaction
commit from wiping out commit roots.

However btrfs_qgroup_trace_extent_post() can be called in a context where
we are holding a write lock on an extent buffer from a subvolume tree,
namely from btrfs_truncate_inode_items(), called either during truncate
or unlink operations. In this case we end up with a lock inversion problem
because the commit_root_sem is a higher level lock, always supposed to be
acquired before locking any extent buffer.

Lockdep detects this lock inversion problem since we switched the extent
buffer locks from custom locks to semaphores, and when running btrfs/158
from fstests, it reported the following trace:

[ 9057.626435] ======================================================
[ 9057.627541] WARNING: possible circular locking dependency detected
[ 9057.628334] 5.14.0-rc2-btrfs-next-93 #1 Not tainted
[ 9057.628961] ------------------------------------------------------
[ 9057.629867] kworker/u16:4/30781 is trying to acquire lock:
[ 9057.630824] ffff8e2590f58760 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 9057.632542]
               but task is already holding lock:
[ 9057.633551] ffff8e25582d4b70 (&fs_info->commit_root_sem){++++}-{3:3}, at: iterate_extent_inodes+0x10b/0x280 [btrfs]
[ 9057.635255]
               which lock already depends on the new lock.

[ 9057.636292]
               the existing dependency chain (in reverse order) is:
[ 9057.637240]
               -> #1 (&fs_info->commit_root_sem){++++}-{3:3}:
[ 9057.638138]        down_read+0x46/0x140
[ 9057.638648]        btrfs_find_all_roots+0x41/0x80 [btrfs]
[ 9057.639398]        btrfs_qgroup_trace_extent_post+0x37/0x70 [btrfs]
[ 9057.640283]        btrfs_add_delayed_data_ref+0x418/0x490 [btrfs]
[ 9057.641114]        btrfs_free_extent+0x35/0xb0 [btrfs]
[ 9057.641819]        btrfs_truncate_inode_items+0x424/0xf70 [btrfs]
[ 9057.642643]        btrfs_evict_inode+0x454/0x4f0 [btrfs]
[ 9057.643418]        evict+0xcf/0x1d0
[ 9057.643895]        do_unlinkat+0x1e9/0x300
[ 9057.644525]        do_syscall_64+0x3b/0xc0
[ 9057.645110]        entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 9057.645835]
               -> #0 (btrfs-tree-00){++++}-{3:3}:
[ 9057.646600]        __lock_acquire+0x130e/0x2210
[ 9057.647248]        lock_acquire+0xd7/0x310
[ 9057.647773]        down_read_nested+0x4b/0x140
[ 9057.648350]        __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 9057.649175]        btrfs_read_lock_root_node+0x31/0x40 [btrfs]
[ 9057.650010]        btrfs_search_slot+0x537/0xc00 [btrfs]
[ 9057.650849]        scrub_print_warning_inode+0x89/0x370 [btrfs]
[ 9057.651733]        iterate_extent_inodes+0x1e3/0x280 [btrfs]
[ 9057.652501]        scrub_print_warning+0x15d/0x2f0 [btrfs]
[ 9057.653264]        scrub_handle_errored_block.isra.0+0x135f/0x1640 [btrfs]
[ 9057.654295]        scrub_bio_end_io_worker+0x101/0x2e0 [btrfs]
[ 9057.655111]        btrfs_work_helper+0xf8/0x400 [btrfs]
[ 9057.655831]        process_one_work+0x247/0x5a0
[ 9057.656425]        worker_thread+0x55/0x3c0
[ 9057.656993]        kthread+0x155/0x180
[ 9057.657494]        ret_from_fork+0x22/0x30
[ 9057.658030]
               other info that might help us debug this:

[ 9057.659064]  Possible unsafe locking scenario:

[ 9057.659824]        CPU0                    CPU1
[ 9057.660402]        ----                    ----
[ 9057.660988]   lock(&fs_info->commit_root_sem);
[ 9057.661581]                                lock(btrfs-tree-00);
[ 9057.662348]                                lock(&fs_info->commit_root_sem);
[ 9057.663254]   lock(btrfs-tree-00);
[ 9057.663690]
                *** DEADLOCK ***

[ 9057.664437] 4 locks held by kworker/u16:4/30781:
[ 9057.665023]  #0: ffff8e25922a1148 ((wq_completion)btrfs-scrub){+.+.}-{0:0}, at: process_one_work+0x1c7/0x5a0
[ 9057.666260]  #1: ffffabb3451ffe70 ((work_completion)(&work->normal_work)){+.+.}-{0:0}, at: process_one_work+0x1c7/0x5a0
[ 9057.667639]  #2: ffff8e25922da198 (&ret->mutex){+.+.}-{3:3}, at: scrub_handle_errored_block.isra.0+0x5d2/0x1640 [btrfs]
[ 9057.669017]  #3: ffff8e25582d4b70 (&fs_info->commit_root_sem){++++}-{3:3}, at: iterate_extent_inodes+0x10b/0x280 [btrfs]
[ 9057.670408]
               stack backtrace:
[ 9057.670976] CPU: 7 PID: 30781 Comm: kworker/u16:4 Not tainted 5.14.0-rc2-btrfs-next-93 #1
[ 9057.672030] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 9057.673492] Workqueue: btrfs-scrub btrfs_work_helper [btrfs]
[ 9057.674258] Call Trace:
[ 9057.674588]  dump_stack_lvl+0x57/0x72
[ 9057.675083]  check_noncircular+0xf3/0x110
[ 9057.675611]  __lock_acquire+0x130e/0x2210
[ 9057.676132]  lock_acquire+0xd7/0x310
[ 9057.676605]  ? __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 9057.677313]  ? lock_is_held_type+0xe8/0x140
[ 9057.677849]  down_read_nested+0x4b/0x140
[ 9057.678349]  ? __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 9057.679068]  __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 9057.679760]  btrfs_read_lock_root_node+0x31/0x40 [btrfs]
[ 9057.680458]  btrfs_search_slot+0x537/0xc00 [btrfs]
[ 9057.681083]  ? _raw_spin_unlock+0x29/0x40
[ 9057.681594]  ? btrfs_find_all_roots_safe+0x11f/0x140 [btrfs]
[ 9057.682336]  scrub_print_warning_inode+0x89/0x370 [btrfs]
[ 9057.683058]  ? btrfs_find_all_roots_safe+0x11f/0x140 [btrfs]
[ 9057.683834]  ? scrub_write_block_to_dev_replace+0xb0/0xb0 [btrfs]
[ 9057.684632]  iterate_extent_inodes+0x1e3/0x280 [btrfs]
[ 9057.685316]  scrub_print_warning+0x15d/0x2f0 [btrfs]
[ 9057.685977]  ? ___ratelimit+0xa4/0x110
[ 9057.686460]  scrub_handle_errored_block.isra.0+0x135f/0x1640 [btrfs]
[ 9057.687316]  scrub_bio_end_io_worker+0x101/0x2e0 [btrfs]
[ 9057.688021]  btrfs_work_helper+0xf8/0x400 [btrfs]
[ 9057.688649]  ? lock_is_held_type+0xe8/0x140
[ 9057.689180]  process_one_work+0x247/0x5a0
[ 9057.689696]  worker_thread+0x55/0x3c0
[ 9057.690175]  ? process_one_work+0x5a0/0x5a0
[ 9057.690731]  kthread+0x155/0x180
[ 9057.691158]  ? set_kthread_struct+0x40/0x40
[ 9057.691697]  ret_from_fork+0x22/0x30

Fix this by making btrfs_find_all_roots() never attempt to lock the
commit_root_sem when it is called from btrfs_qgroup_trace_extent_post().

We can't just pass a non-NULL transaction handle to btrfs_find_all_roots()
from btrfs_qgroup_trace_extent_post(), because that would make backref
lookup not use commit roots and acquire read locks on extent buffers, and
therefore could deadlock when btrfs_qgroup_trace_extent_post() is called
from the btrfs_truncate_inode_items() code path which has acquired a write
lock on an extent buffer of the subvolume btree.

CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-07-22 15:50:07 +02:00

1163 lines
31 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2009 Oracle. All rights reserved.
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include "ctree.h"
#include "delayed-ref.h"
#include "transaction.h"
#include "qgroup.h"
#include "space-info.h"
#include "tree-mod-log.h"
struct kmem_cache *btrfs_delayed_ref_head_cachep;
struct kmem_cache *btrfs_delayed_tree_ref_cachep;
struct kmem_cache *btrfs_delayed_data_ref_cachep;
struct kmem_cache *btrfs_delayed_extent_op_cachep;
/*
* delayed back reference update tracking. For subvolume trees
* we queue up extent allocations and backref maintenance for
* delayed processing. This avoids deep call chains where we
* add extents in the middle of btrfs_search_slot, and it allows
* us to buffer up frequently modified backrefs in an rb tree instead
* of hammering updates on the extent allocation tree.
*/
bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info)
{
struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
bool ret = false;
u64 reserved;
spin_lock(&global_rsv->lock);
reserved = global_rsv->reserved;
spin_unlock(&global_rsv->lock);
/*
* Since the global reserve is just kind of magic we don't really want
* to rely on it to save our bacon, so if our size is more than the
* delayed_refs_rsv and the global rsv then it's time to think about
* bailing.
*/
spin_lock(&delayed_refs_rsv->lock);
reserved += delayed_refs_rsv->reserved;
if (delayed_refs_rsv->size >= reserved)
ret = true;
spin_unlock(&delayed_refs_rsv->lock);
return ret;
}
int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans)
{
u64 num_entries =
atomic_read(&trans->transaction->delayed_refs.num_entries);
u64 avg_runtime;
u64 val;
smp_mb();
avg_runtime = trans->fs_info->avg_delayed_ref_runtime;
val = num_entries * avg_runtime;
if (val >= NSEC_PER_SEC)
return 1;
if (val >= NSEC_PER_SEC / 2)
return 2;
return btrfs_check_space_for_delayed_refs(trans->fs_info);
}
/**
* Release a ref head's reservation
*
* @fs_info: the filesystem
* @nr: number of items to drop
*
* This drops the delayed ref head's count from the delayed refs rsv and frees
* any excess reservation we had.
*/
void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr)
{
struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
u64 num_bytes = btrfs_calc_insert_metadata_size(fs_info, nr);
u64 released = 0;
released = btrfs_block_rsv_release(fs_info, block_rsv, num_bytes, NULL);
if (released)
trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
0, released, 0);
}
/*
* btrfs_update_delayed_refs_rsv - adjust the size of the delayed refs rsv
* @trans - the trans that may have generated delayed refs
*
* This is to be called anytime we may have adjusted trans->delayed_ref_updates,
* it'll calculate the additional size and add it to the delayed_refs_rsv.
*/
void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
u64 num_bytes;
if (!trans->delayed_ref_updates)
return;
num_bytes = btrfs_calc_insert_metadata_size(fs_info,
trans->delayed_ref_updates);
spin_lock(&delayed_rsv->lock);
delayed_rsv->size += num_bytes;
delayed_rsv->full = 0;
spin_unlock(&delayed_rsv->lock);
trans->delayed_ref_updates = 0;
}
/**
* Transfer bytes to our delayed refs rsv
*
* @fs_info: the filesystem
* @src: source block rsv to transfer from
* @num_bytes: number of bytes to transfer
*
* This transfers up to the num_bytes amount from the src rsv to the
* delayed_refs_rsv. Any extra bytes are returned to the space info.
*/
void btrfs_migrate_to_delayed_refs_rsv(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *src,
u64 num_bytes)
{
struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
u64 to_free = 0;
spin_lock(&src->lock);
src->reserved -= num_bytes;
src->size -= num_bytes;
spin_unlock(&src->lock);
spin_lock(&delayed_refs_rsv->lock);
if (delayed_refs_rsv->size > delayed_refs_rsv->reserved) {
u64 delta = delayed_refs_rsv->size -
delayed_refs_rsv->reserved;
if (num_bytes > delta) {
to_free = num_bytes - delta;
num_bytes = delta;
}
} else {
to_free = num_bytes;
num_bytes = 0;
}
if (num_bytes)
delayed_refs_rsv->reserved += num_bytes;
if (delayed_refs_rsv->reserved >= delayed_refs_rsv->size)
delayed_refs_rsv->full = 1;
spin_unlock(&delayed_refs_rsv->lock);
if (num_bytes)
trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
0, num_bytes, 1);
if (to_free)
btrfs_space_info_free_bytes_may_use(fs_info,
delayed_refs_rsv->space_info, to_free);
}
/**
* Refill based on our delayed refs usage
*
* @fs_info: the filesystem
* @flush: control how we can flush for this reservation.
*
* This will refill the delayed block_rsv up to 1 items size worth of space and
* will return -ENOSPC if we can't make the reservation.
*/
int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
enum btrfs_reserve_flush_enum flush)
{
struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
u64 limit = btrfs_calc_insert_metadata_size(fs_info, 1);
u64 num_bytes = 0;
int ret = -ENOSPC;
spin_lock(&block_rsv->lock);
if (block_rsv->reserved < block_rsv->size) {
num_bytes = block_rsv->size - block_rsv->reserved;
num_bytes = min(num_bytes, limit);
}
spin_unlock(&block_rsv->lock);
if (!num_bytes)
return 0;
ret = btrfs_reserve_metadata_bytes(fs_info->extent_root, block_rsv,
num_bytes, flush);
if (ret)
return ret;
btrfs_block_rsv_add_bytes(block_rsv, num_bytes, 0);
trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
0, num_bytes, 1);
return 0;
}
/*
* compare two delayed tree backrefs with same bytenr and type
*/
static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref1,
struct btrfs_delayed_tree_ref *ref2)
{
if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
if (ref1->root < ref2->root)
return -1;
if (ref1->root > ref2->root)
return 1;
} else {
if (ref1->parent < ref2->parent)
return -1;
if (ref1->parent > ref2->parent)
return 1;
}
return 0;
}
/*
* compare two delayed data backrefs with same bytenr and type
*/
static int comp_data_refs(struct btrfs_delayed_data_ref *ref1,
struct btrfs_delayed_data_ref *ref2)
{
if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) {
if (ref1->root < ref2->root)
return -1;
if (ref1->root > ref2->root)
return 1;
if (ref1->objectid < ref2->objectid)
return -1;
if (ref1->objectid > ref2->objectid)
return 1;
if (ref1->offset < ref2->offset)
return -1;
if (ref1->offset > ref2->offset)
return 1;
} else {
if (ref1->parent < ref2->parent)
return -1;
if (ref1->parent > ref2->parent)
return 1;
}
return 0;
}
static int comp_refs(struct btrfs_delayed_ref_node *ref1,
struct btrfs_delayed_ref_node *ref2,
bool check_seq)
{
int ret = 0;
if (ref1->type < ref2->type)
return -1;
if (ref1->type > ref2->type)
return 1;
if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
ref1->type == BTRFS_SHARED_BLOCK_REF_KEY)
ret = comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref1),
btrfs_delayed_node_to_tree_ref(ref2));
else
ret = comp_data_refs(btrfs_delayed_node_to_data_ref(ref1),
btrfs_delayed_node_to_data_ref(ref2));
if (ret)
return ret;
if (check_seq) {
if (ref1->seq < ref2->seq)
return -1;
if (ref1->seq > ref2->seq)
return 1;
}
return 0;
}
/* insert a new ref to head ref rbtree */
static struct btrfs_delayed_ref_head *htree_insert(struct rb_root_cached *root,
struct rb_node *node)
{
struct rb_node **p = &root->rb_root.rb_node;
struct rb_node *parent_node = NULL;
struct btrfs_delayed_ref_head *entry;
struct btrfs_delayed_ref_head *ins;
u64 bytenr;
bool leftmost = true;
ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
bytenr = ins->bytenr;
while (*p) {
parent_node = *p;
entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
href_node);
if (bytenr < entry->bytenr) {
p = &(*p)->rb_left;
} else if (bytenr > entry->bytenr) {
p = &(*p)->rb_right;
leftmost = false;
} else {
return entry;
}
}
rb_link_node(node, parent_node, p);
rb_insert_color_cached(node, root, leftmost);
return NULL;
}
static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,
struct btrfs_delayed_ref_node *ins)
{
struct rb_node **p = &root->rb_root.rb_node;
struct rb_node *node = &ins->ref_node;
struct rb_node *parent_node = NULL;
struct btrfs_delayed_ref_node *entry;
bool leftmost = true;
while (*p) {
int comp;
parent_node = *p;
entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
ref_node);
comp = comp_refs(ins, entry, true);
if (comp < 0) {
p = &(*p)->rb_left;
} else if (comp > 0) {
p = &(*p)->rb_right;
leftmost = false;
} else {
return entry;
}
}
rb_link_node(node, parent_node, p);
rb_insert_color_cached(node, root, leftmost);
return NULL;
}
static struct btrfs_delayed_ref_head *find_first_ref_head(
struct btrfs_delayed_ref_root *dr)
{
struct rb_node *n;
struct btrfs_delayed_ref_head *entry;
n = rb_first_cached(&dr->href_root);
if (!n)
return NULL;
entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
return entry;
}
/*
* Find a head entry based on bytenr. This returns the delayed ref head if it
* was able to find one, or NULL if nothing was in that spot. If return_bigger
* is given, the next bigger entry is returned if no exact match is found.
*/
static struct btrfs_delayed_ref_head *find_ref_head(
struct btrfs_delayed_ref_root *dr, u64 bytenr,
bool return_bigger)
{
struct rb_root *root = &dr->href_root.rb_root;
struct rb_node *n;
struct btrfs_delayed_ref_head *entry;
n = root->rb_node;
entry = NULL;
while (n) {
entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
if (bytenr < entry->bytenr)
n = n->rb_left;
else if (bytenr > entry->bytenr)
n = n->rb_right;
else
return entry;
}
if (entry && return_bigger) {
if (bytenr > entry->bytenr) {
n = rb_next(&entry->href_node);
if (!n)
return NULL;
entry = rb_entry(n, struct btrfs_delayed_ref_head,
href_node);
}
return entry;
}
return NULL;
}
int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head)
{
lockdep_assert_held(&delayed_refs->lock);
if (mutex_trylock(&head->mutex))
return 0;
refcount_inc(&head->refs);
spin_unlock(&delayed_refs->lock);
mutex_lock(&head->mutex);
spin_lock(&delayed_refs->lock);
if (RB_EMPTY_NODE(&head->href_node)) {
mutex_unlock(&head->mutex);
btrfs_put_delayed_ref_head(head);
return -EAGAIN;
}
btrfs_put_delayed_ref_head(head);
return 0;
}
static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head,
struct btrfs_delayed_ref_node *ref)
{
lockdep_assert_held(&head->lock);
rb_erase_cached(&ref->ref_node, &head->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);
ref->in_tree = 0;
btrfs_put_delayed_ref(ref);
atomic_dec(&delayed_refs->num_entries);
}
static bool merge_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head,
struct btrfs_delayed_ref_node *ref,
u64 seq)
{
struct btrfs_delayed_ref_node *next;
struct rb_node *node = rb_next(&ref->ref_node);
bool done = false;
while (!done && node) {
int mod;
next = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
node = rb_next(node);
if (seq && next->seq >= seq)
break;
if (comp_refs(ref, next, false))
break;
if (ref->action == next->action) {
mod = next->ref_mod;
} else {
if (ref->ref_mod < next->ref_mod) {
swap(ref, next);
done = true;
}
mod = -next->ref_mod;
}
drop_delayed_ref(trans, delayed_refs, head, next);
ref->ref_mod += mod;
if (ref->ref_mod == 0) {
drop_delayed_ref(trans, delayed_refs, head, ref);
done = true;
} else {
/*
* Can't have multiples of the same ref on a tree block.
*/
WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
}
}
return done;
}
void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_delayed_ref_node *ref;
struct rb_node *node;
u64 seq = 0;
lockdep_assert_held(&head->lock);
if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))
return;
/* We don't have too many refs to merge for data. */
if (head->is_data)
return;
seq = btrfs_tree_mod_log_lowest_seq(fs_info);
again:
for (node = rb_first_cached(&head->ref_tree); node;
node = rb_next(node)) {
ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
if (seq && ref->seq >= seq)
continue;
if (merge_ref(trans, delayed_refs, head, ref, seq))
goto again;
}
}
int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq)
{
int ret = 0;
u64 min_seq = btrfs_tree_mod_log_lowest_seq(fs_info);
if (min_seq != 0 && seq >= min_seq) {
btrfs_debug(fs_info,
"holding back delayed_ref %llu, lowest is %llu",
seq, min_seq);
ret = 1;
}
return ret;
}
struct btrfs_delayed_ref_head *btrfs_select_ref_head(
struct btrfs_delayed_ref_root *delayed_refs)
{
struct btrfs_delayed_ref_head *head;
again:
head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,
true);
if (!head && delayed_refs->run_delayed_start != 0) {
delayed_refs->run_delayed_start = 0;
head = find_first_ref_head(delayed_refs);
}
if (!head)
return NULL;
while (head->processing) {
struct rb_node *node;
node = rb_next(&head->href_node);
if (!node) {
if (delayed_refs->run_delayed_start == 0)
return NULL;
delayed_refs->run_delayed_start = 0;
goto again;
}
head = rb_entry(node, struct btrfs_delayed_ref_head,
href_node);
}
head->processing = 1;
WARN_ON(delayed_refs->num_heads_ready == 0);
delayed_refs->num_heads_ready--;
delayed_refs->run_delayed_start = head->bytenr +
head->num_bytes;
return head;
}
void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head)
{
lockdep_assert_held(&delayed_refs->lock);
lockdep_assert_held(&head->lock);
rb_erase_cached(&head->href_node, &delayed_refs->href_root);
RB_CLEAR_NODE(&head->href_node);
atomic_dec(&delayed_refs->num_entries);
delayed_refs->num_heads--;
if (head->processing == 0)
delayed_refs->num_heads_ready--;
}
/*
* Helper to insert the ref_node to the tail or merge with tail.
*
* Return 0 for insert.
* Return >0 for merge.
*/
static int insert_delayed_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *root,
struct btrfs_delayed_ref_head *href,
struct btrfs_delayed_ref_node *ref)
{
struct btrfs_delayed_ref_node *exist;
int mod;
int ret = 0;
spin_lock(&href->lock);
exist = tree_insert(&href->ref_tree, ref);
if (!exist)
goto inserted;
/* Now we are sure we can merge */
ret = 1;
if (exist->action == ref->action) {
mod = ref->ref_mod;
} else {
/* Need to change action */
if (exist->ref_mod < ref->ref_mod) {
exist->action = ref->action;
mod = -exist->ref_mod;
exist->ref_mod = ref->ref_mod;
if (ref->action == BTRFS_ADD_DELAYED_REF)
list_add_tail(&exist->add_list,
&href->ref_add_list);
else if (ref->action == BTRFS_DROP_DELAYED_REF) {
ASSERT(!list_empty(&exist->add_list));
list_del(&exist->add_list);
} else {
ASSERT(0);
}
} else
mod = -ref->ref_mod;
}
exist->ref_mod += mod;
/* remove existing tail if its ref_mod is zero */
if (exist->ref_mod == 0)
drop_delayed_ref(trans, root, href, exist);
spin_unlock(&href->lock);
return ret;
inserted:
if (ref->action == BTRFS_ADD_DELAYED_REF)
list_add_tail(&ref->add_list, &href->ref_add_list);
atomic_inc(&root->num_entries);
spin_unlock(&href->lock);
return ret;
}
/*
* helper function to update the accounting in the head ref
* existing and update must have the same bytenr
*/
static noinline void update_existing_head_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_head *existing,
struct btrfs_delayed_ref_head *update)
{
struct btrfs_delayed_ref_root *delayed_refs =
&trans->transaction->delayed_refs;
struct btrfs_fs_info *fs_info = trans->fs_info;
int old_ref_mod;
BUG_ON(existing->is_data != update->is_data);
spin_lock(&existing->lock);
if (update->must_insert_reserved) {
/* if the extent was freed and then
* reallocated before the delayed ref
* entries were processed, we can end up
* with an existing head ref without
* the must_insert_reserved flag set.
* Set it again here
*/
existing->must_insert_reserved = update->must_insert_reserved;
/*
* update the num_bytes so we make sure the accounting
* is done correctly
*/
existing->num_bytes = update->num_bytes;
}
if (update->extent_op) {
if (!existing->extent_op) {
existing->extent_op = update->extent_op;
} else {
if (update->extent_op->update_key) {
memcpy(&existing->extent_op->key,
&update->extent_op->key,
sizeof(update->extent_op->key));
existing->extent_op->update_key = true;
}
if (update->extent_op->update_flags) {
existing->extent_op->flags_to_set |=
update->extent_op->flags_to_set;
existing->extent_op->update_flags = true;
}
btrfs_free_delayed_extent_op(update->extent_op);
}
}
/*
* update the reference mod on the head to reflect this new operation,
* only need the lock for this case cause we could be processing it
* currently, for refs we just added we know we're a-ok.
*/
old_ref_mod = existing->total_ref_mod;
existing->ref_mod += update->ref_mod;
existing->total_ref_mod += update->ref_mod;
/*
* If we are going to from a positive ref mod to a negative or vice
* versa we need to make sure to adjust pending_csums accordingly.
*/
if (existing->is_data) {
u64 csum_leaves =
btrfs_csum_bytes_to_leaves(fs_info,
existing->num_bytes);
if (existing->total_ref_mod >= 0 && old_ref_mod < 0) {
delayed_refs->pending_csums -= existing->num_bytes;
btrfs_delayed_refs_rsv_release(fs_info, csum_leaves);
}
if (existing->total_ref_mod < 0 && old_ref_mod >= 0) {
delayed_refs->pending_csums += existing->num_bytes;
trans->delayed_ref_updates += csum_leaves;
}
}
spin_unlock(&existing->lock);
}
static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
struct btrfs_qgroup_extent_record *qrecord,
u64 bytenr, u64 num_bytes, u64 ref_root,
u64 reserved, int action, bool is_data,
bool is_system)
{
int count_mod = 1;
int must_insert_reserved = 0;
/* If reserved is provided, it must be a data extent. */
BUG_ON(!is_data && reserved);
/*
* The head node stores the sum of all the mods, so dropping a ref
* should drop the sum in the head node by one.
*/
if (action == BTRFS_UPDATE_DELAYED_HEAD)
count_mod = 0;
else if (action == BTRFS_DROP_DELAYED_REF)
count_mod = -1;
/*
* BTRFS_ADD_DELAYED_EXTENT means that we need to update the reserved
* accounting when the extent is finally added, or if a later
* modification deletes the delayed ref without ever inserting the
* extent into the extent allocation tree. ref->must_insert_reserved
* is the flag used to record that accounting mods are required.
*
* Once we record must_insert_reserved, switch the action to
* BTRFS_ADD_DELAYED_REF because other special casing is not required.
*/
if (action == BTRFS_ADD_DELAYED_EXTENT)
must_insert_reserved = 1;
else
must_insert_reserved = 0;
refcount_set(&head_ref->refs, 1);
head_ref->bytenr = bytenr;
head_ref->num_bytes = num_bytes;
head_ref->ref_mod = count_mod;
head_ref->must_insert_reserved = must_insert_reserved;
head_ref->is_data = is_data;
head_ref->is_system = is_system;
head_ref->ref_tree = RB_ROOT_CACHED;
INIT_LIST_HEAD(&head_ref->ref_add_list);
RB_CLEAR_NODE(&head_ref->href_node);
head_ref->processing = 0;
head_ref->total_ref_mod = count_mod;
spin_lock_init(&head_ref->lock);
mutex_init(&head_ref->mutex);
if (qrecord) {
if (ref_root && reserved) {
qrecord->data_rsv = reserved;
qrecord->data_rsv_refroot = ref_root;
}
qrecord->bytenr = bytenr;
qrecord->num_bytes = num_bytes;
qrecord->old_roots = NULL;
}
}
/*
* helper function to actually insert a head node into the rbtree.
* this does all the dirty work in terms of maintaining the correct
* overall modification count.
*/
static noinline struct btrfs_delayed_ref_head *
add_delayed_ref_head(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_head *head_ref,
struct btrfs_qgroup_extent_record *qrecord,
int action, int *qrecord_inserted_ret)
{
struct btrfs_delayed_ref_head *existing;
struct btrfs_delayed_ref_root *delayed_refs;
int qrecord_inserted = 0;
delayed_refs = &trans->transaction->delayed_refs;
/* Record qgroup extent info if provided */
if (qrecord) {
if (btrfs_qgroup_trace_extent_nolock(trans->fs_info,
delayed_refs, qrecord))
kfree(qrecord);
else
qrecord_inserted = 1;
}
trace_add_delayed_ref_head(trans->fs_info, head_ref, action);
existing = htree_insert(&delayed_refs->href_root,
&head_ref->href_node);
if (existing) {
update_existing_head_ref(trans, existing, head_ref);
/*
* we've updated the existing ref, free the newly
* allocated ref
*/
kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
head_ref = existing;
} else {
if (head_ref->is_data && head_ref->ref_mod < 0) {
delayed_refs->pending_csums += head_ref->num_bytes;
trans->delayed_ref_updates +=
btrfs_csum_bytes_to_leaves(trans->fs_info,
head_ref->num_bytes);
}
delayed_refs->num_heads++;
delayed_refs->num_heads_ready++;
atomic_inc(&delayed_refs->num_entries);
trans->delayed_ref_updates++;
}
if (qrecord_inserted_ret)
*qrecord_inserted_ret = qrecord_inserted;
return head_ref;
}
/*
* init_delayed_ref_common - Initialize the structure which represents a
* modification to a an extent.
*
* @fs_info: Internal to the mounted filesystem mount structure.
*
* @ref: The structure which is going to be initialized.
*
* @bytenr: The logical address of the extent for which a modification is
* going to be recorded.
*
* @num_bytes: Size of the extent whose modification is being recorded.
*
* @ref_root: The id of the root where this modification has originated, this
* can be either one of the well-known metadata trees or the
* subvolume id which references this extent.
*
* @action: Can be one of BTRFS_ADD_DELAYED_REF/BTRFS_DROP_DELAYED_REF or
* BTRFS_ADD_DELAYED_EXTENT
*
* @ref_type: Holds the type of the extent which is being recorded, can be
* one of BTRFS_SHARED_BLOCK_REF_KEY/BTRFS_TREE_BLOCK_REF_KEY
* when recording a metadata extent or BTRFS_SHARED_DATA_REF_KEY/
* BTRFS_EXTENT_DATA_REF_KEY when recording data extent
*/
static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_node *ref,
u64 bytenr, u64 num_bytes, u64 ref_root,
int action, u8 ref_type)
{
u64 seq = 0;
if (action == BTRFS_ADD_DELAYED_EXTENT)
action = BTRFS_ADD_DELAYED_REF;
if (is_fstree(ref_root))
seq = atomic64_read(&fs_info->tree_mod_seq);
refcount_set(&ref->refs, 1);
ref->bytenr = bytenr;
ref->num_bytes = num_bytes;
ref->ref_mod = 1;
ref->action = action;
ref->is_head = 0;
ref->in_tree = 1;
ref->seq = seq;
ref->type = ref_type;
RB_CLEAR_NODE(&ref->ref_node);
INIT_LIST_HEAD(&ref->add_list);
}
/*
* add a delayed tree ref. This does all of the accounting required
* to make sure the delayed ref is eventually processed before this
* transaction commits.
*/
int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
struct btrfs_ref *generic_ref,
struct btrfs_delayed_extent_op *extent_op)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_delayed_tree_ref *ref;
struct btrfs_delayed_ref_head *head_ref;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_qgroup_extent_record *record = NULL;
int qrecord_inserted;
bool is_system;
int action = generic_ref->action;
int level = generic_ref->tree_ref.level;
int ret;
u64 bytenr = generic_ref->bytenr;
u64 num_bytes = generic_ref->len;
u64 parent = generic_ref->parent;
u8 ref_type;
is_system = (generic_ref->real_root == BTRFS_CHUNK_TREE_OBJECTID);
ASSERT(generic_ref->type == BTRFS_REF_METADATA && generic_ref->action);
BUG_ON(extent_op && extent_op->is_data);
ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
if (!ref)
return -ENOMEM;
head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
if (!head_ref) {
kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
return -ENOMEM;
}
if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
is_fstree(generic_ref->real_root) &&
is_fstree(generic_ref->tree_ref.root) &&
!generic_ref->skip_qgroup) {
record = kzalloc(sizeof(*record), GFP_NOFS);
if (!record) {
kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
return -ENOMEM;
}
}
if (parent)
ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
else
ref_type = BTRFS_TREE_BLOCK_REF_KEY;
init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
generic_ref->tree_ref.root, action, ref_type);
ref->root = generic_ref->tree_ref.root;
ref->parent = parent;
ref->level = level;
init_delayed_ref_head(head_ref, record, bytenr, num_bytes,
generic_ref->tree_ref.root, 0, action, false,
is_system);
head_ref->extent_op = extent_op;
delayed_refs = &trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
/*
* insert both the head node and the new ref without dropping
* the spin lock
*/
head_ref = add_delayed_ref_head(trans, head_ref, record,
action, &qrecord_inserted);
ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
spin_unlock(&delayed_refs->lock);
/*
* Need to update the delayed_refs_rsv with any changes we may have
* made.
*/
btrfs_update_delayed_refs_rsv(trans);
trace_add_delayed_tree_ref(fs_info, &ref->node, ref,
action == BTRFS_ADD_DELAYED_EXTENT ?
BTRFS_ADD_DELAYED_REF : action);
if (ret > 0)
kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
if (qrecord_inserted)
btrfs_qgroup_trace_extent_post(trans, record);
return 0;
}
/*
* add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
*/
int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
struct btrfs_ref *generic_ref,
u64 reserved)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_delayed_data_ref *ref;
struct btrfs_delayed_ref_head *head_ref;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_qgroup_extent_record *record = NULL;
int qrecord_inserted;
int action = generic_ref->action;
int ret;
u64 bytenr = generic_ref->bytenr;
u64 num_bytes = generic_ref->len;
u64 parent = generic_ref->parent;
u64 ref_root = generic_ref->data_ref.ref_root;
u64 owner = generic_ref->data_ref.ino;
u64 offset = generic_ref->data_ref.offset;
u8 ref_type;
ASSERT(generic_ref->type == BTRFS_REF_DATA && action);
ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
if (!ref)
return -ENOMEM;
if (parent)
ref_type = BTRFS_SHARED_DATA_REF_KEY;
else
ref_type = BTRFS_EXTENT_DATA_REF_KEY;
init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
ref_root, action, ref_type);
ref->root = ref_root;
ref->parent = parent;
ref->objectid = owner;
ref->offset = offset;
head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
if (!head_ref) {
kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
return -ENOMEM;
}
if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
is_fstree(ref_root) &&
is_fstree(generic_ref->real_root) &&
!generic_ref->skip_qgroup) {
record = kzalloc(sizeof(*record), GFP_NOFS);
if (!record) {
kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
kmem_cache_free(btrfs_delayed_ref_head_cachep,
head_ref);
return -ENOMEM;
}
}
init_delayed_ref_head(head_ref, record, bytenr, num_bytes, ref_root,
reserved, action, true, false);
head_ref->extent_op = NULL;
delayed_refs = &trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
/*
* insert both the head node and the new ref without dropping
* the spin lock
*/
head_ref = add_delayed_ref_head(trans, head_ref, record,
action, &qrecord_inserted);
ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
spin_unlock(&delayed_refs->lock);
/*
* Need to update the delayed_refs_rsv with any changes we may have
* made.
*/
btrfs_update_delayed_refs_rsv(trans);
trace_add_delayed_data_ref(trans->fs_info, &ref->node, ref,
action == BTRFS_ADD_DELAYED_EXTENT ?
BTRFS_ADD_DELAYED_REF : action);
if (ret > 0)
kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
if (qrecord_inserted)
return btrfs_qgroup_trace_extent_post(trans, record);
return 0;
}
int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
struct btrfs_delayed_extent_op *extent_op)
{
struct btrfs_delayed_ref_head *head_ref;
struct btrfs_delayed_ref_root *delayed_refs;
head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
if (!head_ref)
return -ENOMEM;
init_delayed_ref_head(head_ref, NULL, bytenr, num_bytes, 0, 0,
BTRFS_UPDATE_DELAYED_HEAD, extent_op->is_data,
false);
head_ref->extent_op = extent_op;
delayed_refs = &trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
add_delayed_ref_head(trans, head_ref, NULL, BTRFS_UPDATE_DELAYED_HEAD,
NULL);
spin_unlock(&delayed_refs->lock);
/*
* Need to update the delayed_refs_rsv with any changes we may have
* made.
*/
btrfs_update_delayed_refs_rsv(trans);
return 0;
}
/*
* This does a simple search for the head node for a given extent. Returns the
* head node if found, or NULL if not.
*/
struct btrfs_delayed_ref_head *
btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 bytenr)
{
lockdep_assert_held(&delayed_refs->lock);
return find_ref_head(delayed_refs, bytenr, false);
}
void __cold btrfs_delayed_ref_exit(void)
{
kmem_cache_destroy(btrfs_delayed_ref_head_cachep);
kmem_cache_destroy(btrfs_delayed_tree_ref_cachep);
kmem_cache_destroy(btrfs_delayed_data_ref_cachep);
kmem_cache_destroy(btrfs_delayed_extent_op_cachep);
}
int __init btrfs_delayed_ref_init(void)
{
btrfs_delayed_ref_head_cachep = kmem_cache_create(
"btrfs_delayed_ref_head",
sizeof(struct btrfs_delayed_ref_head), 0,
SLAB_MEM_SPREAD, NULL);
if (!btrfs_delayed_ref_head_cachep)
goto fail;
btrfs_delayed_tree_ref_cachep = kmem_cache_create(
"btrfs_delayed_tree_ref",
sizeof(struct btrfs_delayed_tree_ref), 0,
SLAB_MEM_SPREAD, NULL);
if (!btrfs_delayed_tree_ref_cachep)
goto fail;
btrfs_delayed_data_ref_cachep = kmem_cache_create(
"btrfs_delayed_data_ref",
sizeof(struct btrfs_delayed_data_ref), 0,
SLAB_MEM_SPREAD, NULL);
if (!btrfs_delayed_data_ref_cachep)
goto fail;
btrfs_delayed_extent_op_cachep = kmem_cache_create(
"btrfs_delayed_extent_op",
sizeof(struct btrfs_delayed_extent_op), 0,
SLAB_MEM_SPREAD, NULL);
if (!btrfs_delayed_extent_op_cachep)
goto fail;
return 0;
fail:
btrfs_delayed_ref_exit();
return -ENOMEM;
}