Limit the number of zones reclaimed in flush_space()'s RECLAIM_ZONES
state.
This prevents possibly long running reclaim sweeps to block other tasks in
the system, while the system is under pressure anyways, causing the
tasks to hang.
An example of this can be seen here, triggered by fstests generic/551:
generic/551 [ 27.042349] run fstests generic/551 at 2026-02-27 11:05:30
BTRFS: device fsid
78c16e29-20d9-4c8e-bc04-
7ba431be38ff devid 1 transid 8 /dev/vdb (254:16) scanned by mount (806)
BTRFS info (device vdb): first mount of filesystem
78c16e29-20d9-4c8e-bc04-
7ba431be38ff
BTRFS info (device vdb): using crc32c checksum algorithm
BTRFS info (device vdb): host-managed zoned block device /dev/vdb, 64 zones of
268435456 bytes
BTRFS info (device vdb): zoned mode enabled with zone size
268435456
BTRFS info (device vdb): checking UUID tree
BTRFS info (device vdb): enabling free space tree
INFO: task kworker/u38:1:90 blocked for more than 120 seconds.
Not tainted 7.0.0-rc1+ #345
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u38:1 state:D stack:0 pid:90 tgid:90 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound btrfs_async_reclaim_data_space
Call Trace:
<TASK>
__schedule+0x34f/0xe70
schedule+0x41/0x140
schedule_timeout+0xa3/0x110
? mark_held_locks+0x40/0x70
? lockdep_hardirqs_on_prepare+0xd8/0x1c0
? trace_hardirqs_on+0x18/0x100
? lockdep_hardirqs_on+0x84/0x130
? _raw_spin_unlock_irq+0x33/0x50
wait_for_completion+0xa4/0x150
? __flush_work+0x24c/0x550
__flush_work+0x339/0x550
? __pfx_wq_barrier_func+0x10/0x10
? wait_for_completion+0x39/0x150
flush_space+0x243/0x660
? find_held_lock+0x2b/0x80
? kvm_sched_clock_read+0x11/0x20
? local_clock_noinstr+0x17/0x110
? local_clock+0x15/0x30
? lock_release+0x1b7/0x4b0
do_async_reclaim_data_space+0xe8/0x160
btrfs_async_reclaim_data_space+0x19/0x30
process_one_work+0x20a/0x5f0
? lock_is_held_type+0xcd/0x130
worker_thread+0x1e2/0x3c0
? __pfx_worker_thread+0x10/0x10
kthread+0x103/0x150
? __pfx_kthread+0x10/0x10
ret_from_fork+0x20d/0x320
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/67:
#0:
ffffffff824d58e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x194
2 locks held by kworker/u38:1/90:
#0:
ffff8881000aa158 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x3c4/0x5f0
#1:
ffffc90000c17e58 ((work_completion)(&fs_info->async_data_reclaim_work)){+.+.}-{0:0}, at: process_one_work+0x1c0/0x5f0
5 locks held by kworker/u39:1/191:
#0:
ffff8881000aa158 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x3c4/0x5f0
#1:
ffffc90000dfbe58 ((work_completion)(&fs_info->reclaim_bgs_work)){+.+.}-{0:0}, at: process_one_work+0x1c0/0x5f0
#2:
ffff888101da0420 (sb_writers#9){.+.+}-{0:0}, at: process_one_work+0x20a/0x5f0
#3:
ffff88811040a648 (&fs_info->reclaim_bgs_lock){+.+.}-{4:4}, at: btrfs_reclaim_bgs_work+0x1de/0x770
#4:
ffff888110408a18 (&fs_info->cleaner_mutex){+.+.}-{4:4}, at: btrfs_relocate_block_group+0x95a/0x20f0
1 lock held by aio-dio-write-v/980:
#0:
ffff888110093008 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: btrfs_inode_lock+0x51/0xb0
=============================================
To prevent these long running reclaims from blocking the system, only
reclaim 5 block_groups in the RECLAIM_ZONES state of flush_space(). Also
as these reclaims are now constrained, it opens up the use for a
synchronous call to brtfs_reclaim_block_groups(), eliminating the need
to place the reclaim task on a workqueue and then flushing the workqueue
again.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
return true;
}
-static int btrfs_reclaim_block_group(struct btrfs_block_group *bg)
+static int btrfs_reclaim_block_group(struct btrfs_block_group *bg, int *reclaimed)
{
struct btrfs_fs_info *fs_info = bg->fs_info;
struct btrfs_space_info *space_info = bg->space_info;
if (space_info->total_bytes < old_total)
btrfs_set_periodic_reclaim_ready(space_info, true);
spin_unlock(&space_info->lock);
+ if (!ret)
+ (*reclaimed)++;
return ret;
}
-static void btrfs_reclaim_block_groups(struct btrfs_fs_info *fs_info)
+void btrfs_reclaim_block_groups(struct btrfs_fs_info *fs_info, unsigned int limit)
{
struct btrfs_block_group *bg;
struct btrfs_space_info *space_info;
LIST_HEAD(retry_list);
+ int reclaimed = 0;
if (!btrfs_should_reclaim(fs_info))
return;
space_info = bg->space_info;
spin_unlock(&fs_info->unused_bgs_lock);
- ret = btrfs_reclaim_block_group(bg);
+ ret = btrfs_reclaim_block_group(bg, &reclaimed);
if (ret && !READ_ONCE(space_info->periodic_reclaim))
btrfs_link_bg_list(bg, &retry_list);
if (!mutex_trylock(&fs_info->reclaim_bgs_lock))
goto end;
spin_lock(&fs_info->unused_bgs_lock);
+ if (reclaimed >= limit)
+ break;
}
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
struct btrfs_fs_info *fs_info =
container_of(work, struct btrfs_fs_info, reclaim_bgs_work);
- btrfs_reclaim_block_groups(fs_info);
+ btrfs_reclaim_block_groups(fs_info, -1);
}
void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info)
struct btrfs_chunk_map *map);
void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info);
void btrfs_mark_bg_unused(struct btrfs_block_group *bg);
+void btrfs_reclaim_block_groups(struct btrfs_fs_info *fs_info, unsigned int limit);
void btrfs_reclaim_bgs_work(struct work_struct *work);
void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info);
void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg);
#define BTRFS_UNALLOC_BLOCK_GROUP_TARGET (10ULL)
+#define BTRFS_ZONED_SYNC_RECLAIM_BATCH (5)
+
/*
* Calculate chunk size depending on volume type (regular or zoned).
*/
if (btrfs_is_zoned(fs_info)) {
btrfs_reclaim_sweep(fs_info);
btrfs_delete_unused_bgs(fs_info);
- btrfs_reclaim_bgs(fs_info);
- flush_work(&fs_info->reclaim_bgs_work);
+ btrfs_reclaim_block_groups(fs_info,
+ BTRFS_ZONED_SYNC_RECLAIM_BATCH);
ASSERT(current->journal_info == NULL);
ret = btrfs_commit_current_transaction(root);
} else {
projects / thirdparty / kernel / linux.git / commitdiff
