From: Chao Yu yuchao0@huawei.com
[ Upstream commit 466357dc9b5ff555d16b7f9a0ff264eb9d5d908b ]
generic/232 reports below deadlock:
fsstress D 0 96980 96969 0x00084000 Call Trace: schedule+0x4a/0xb0 io_schedule+0x12/0x40 __lock_page+0x127/0x1d0 pagecache_get_page+0x1d8/0x250 prepare_compress_overwrite+0xe0/0x490 [f2fs] f2fs_prepare_compress_overwrite+0x5d/0x80 [f2fs] f2fs_write_begin+0x833/0xb90 [f2fs] f2fs_quota_write+0x145/0x1e0 [f2fs] write_blk+0x36/0x80 [quota_tree] do_insert_tree+0x2ac/0x4a0 [quota_tree] do_insert_tree+0x26e/0x4a0 [quota_tree] qtree_write_dquot+0x70/0x190 [quota_tree] v2_write_dquot+0x43/0x90 [quota_v2] dquot_acquire+0x77/0x100 f2fs_dquot_acquire+0x2f/0x60 [f2fs] dqget+0x310/0x450 dquot_transfer+0xb2/0x120 f2fs_setattr+0x11a/0x4a0 [f2fs] notify_change+0x349/0x480 chown_common+0x168/0x1c0 do_fchownat+0xbc/0xf0 __x64_sys_lchown+0x21/0x30 do_syscall_64+0x5f/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9
task PC stack pid father kworker/u256:0 D 0 103444 2 0x80084000 Workqueue: writeback wb_workfn (flush-251:1) Call Trace: schedule+0x4a/0xb0 schedule_timeout+0x15e/0x2f0 io_schedule_timeout+0x19/0x40 congestion_wait+0x7e/0x120 f2fs_write_multi_pages+0x12a/0x840 [f2fs] f2fs_write_cache_pages+0x48f/0x790 [f2fs] f2fs_write_data_pages+0x2db/0x330 [f2fs] do_writepages+0x1a/0x60 __writeback_single_inode+0x3d/0x340 writeback_sb_inodes+0x225/0x4a0 wb_writeback+0xf7/0x320 wb_workfn+0xba/0x470 process_one_work+0x16c/0x3f0 worker_thread+0x4c/0x440 kthread+0xf8/0x130 ret_from_fork+0x35/0x40
fsstress D 0 5277 5266 0x00084000 Call Trace: schedule+0x4a/0xb0 rwsem_down_write_slowpath+0x29d/0x540 block_operations+0x105/0x360 [f2fs] f2fs_write_checkpoint+0x101/0x1010 [f2fs] f2fs_sync_fs+0xa8/0x130 [f2fs] f2fs_do_sync_file+0x1ad/0x890 [f2fs] do_fsync+0x38/0x60 __x64_sys_fdatasync+0x13/0x20 do_syscall_64+0x5f/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9
The root cause is there is potential deadlock between quota data update and writeback.
Kworker Thread B Thread C - f2fs_write_cache_pages - lock whole cluster --- A - f2fs_write_multi_pages - f2fs_write_raw_pages - f2fs_write_single_data_page - f2fs_do_write_data_page - f2fs_setattr - f2fs_lock_op --- B - f2fs_write_checkpoint - block_operations - f2fs_lock_all --- B - dquot_transfer - f2fs_quota_write - f2fs_prepare_compress_overwrite - pagecache_get_page --- A - f2fs_trylock_op failed --- B - congestion_wait - goto rewrite
To fix this issue, during quota file writeback, just redirty all pages left in cluster rather holding pages' lock in cluster and looping retrying lock cp_rwsem.
Signed-off-by: Chao Yu yuchao0@huawei.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/compress.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index eb84c13c1182c..ad8e25a1fbc26 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -988,6 +988,15 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, unlock_page(cc->rpages[i]); ret = 0; } else if (ret == -EAGAIN) { + /* + * for quota file, just redirty left pages to + * avoid deadlock caused by cluster update race + * from foreground operation. + */ + if (IS_NOQUOTA(cc->inode)) { + err = 0; + goto out_err; + } ret = 0; cond_resched(); congestion_wait(BLK_RW_ASYNC, HZ/50); @@ -996,16 +1005,12 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, goto retry_write; } err = ret; - goto out_fail; + goto out_err; }
*submitted += _submitted; } return 0; - -out_fail: - /* TODO: revoke partially updated block addresses */ - BUG_ON(compr_blocks); out_err: for (++i; i < cc->cluster_size; i++) { if (!cc->rpages[i])