Quota code itself is serializing the operations by taking mutex_lock.
It seems a below deadlock can happen if GF_NOFS is not used in
f2fs_quota_read

__switch_to+0x88
__schedule+0x5b0
schedule+0x78
schedule_preempt_disabled+0x20
__mutex_lock_slowpath+0xdc   		//mutex owner is itself
mutex_lock+0x2c
dquot_commit+0x30			//mutex_lock(&dqopt->dqio_mutex);
dqput+0xe0
__dquot_drop+0x80
dquot_drop+0x48
f2fs_evict_inode+0x218
evict+0xa8
dispose_list+0x3c
prune_icache_sb+0x58
super_cache_scan+0xf4
do_shrink_slab+0x208
shrink_slab.part.40+0xac
shrink_zone+0x1b0
do_try_to_free_pages+0x25c
try_to_free_pages+0x164
__alloc_pages_nodemask+0x534
do_read_cache_page+0x6c
read_cache_page+0x14
f2fs_quota_read+0xa4
read_blk+0x54
find_tree_dqentry+0xe4
find_tree_dqentry+0xb8
find_tree_dqentry+0xb8
find_tree_dqentry+0xb8
qtree_read_dquot+0x68
v2_read_dquot+0x24
dquot_acquire+0x5c			// mutex_lock(&dqopt->dqio_mutex);
dqget+0x238
__dquot_initialize+0xd4
dquot_initialize+0x10
dquot_file_open+0x34
f2fs_file_open+0x6c
do_dentry_open+0x1e4
vfs_open+0x6c
path_openat+0xa20
do_filp_open+0x4c
do_sys_open+0x178
Signed-off-by: NRitesh Harjani <riteshh@codeaurora.org>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>