From: Chao Yu chao@kernel.org
[ Upstream commit 9de71ede81e6d1a111fdd868b2d78d459fa77f80 ]
xfstest generic/587 reports a deadlock issue as below:
====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc1 #69 Not tainted ------------------------------------------------------ repquota/8606 is trying to acquire lock: ffff888022ac9320 (&sb->s_type->i_mutex_key#18){+.+.}-{3:3}, at: f2fs_quota_sync+0x207/0x300 [f2fs]
but task is already holding lock: ffff8880084bcde8 (&sbi->quota_sem){.+.+}-{3:3}, at: f2fs_quota_sync+0x59/0x300 [f2fs]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&sbi->quota_sem){.+.+}-{3:3}: __lock_acquire+0x648/0x10b0 lock_acquire+0x128/0x470 down_read+0x3b/0x2a0 f2fs_quota_sync+0x59/0x300 [f2fs] f2fs_quota_on+0x48/0x100 [f2fs] do_quotactl+0x5e3/0xb30 __x64_sys_quotactl+0x23a/0x4e0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #1 (&sbi->cp_rwsem){++++}-{3:3}: __lock_acquire+0x648/0x10b0 lock_acquire+0x128/0x470 down_read+0x3b/0x2a0 f2fs_unlink+0x353/0x670 [f2fs] vfs_unlink+0x1c7/0x380 do_unlinkat+0x413/0x4b0 __x64_sys_unlinkat+0x50/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #0 (&sb->s_type->i_mutex_key#18){+.+.}-{3:3}: check_prev_add+0xdc/0xb30 validate_chain+0xa67/0xb20 __lock_acquire+0x648/0x10b0 lock_acquire+0x128/0x470 down_write+0x39/0xc0 f2fs_quota_sync+0x207/0x300 [f2fs] do_quotactl+0xaff/0xb30 __x64_sys_quotactl+0x23a/0x4e0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of: &sb->s_type->i_mutex_key#18 --> &sbi->cp_rwsem --> &sbi->quota_sem
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&sbi->quota_sem); lock(&sbi->cp_rwsem); lock(&sbi->quota_sem); lock(&sb->s_type->i_mutex_key#18);
*** DEADLOCK ***
3 locks held by repquota/8606: #0: ffff88801efac0e0 (&type->s_umount_key#53){++++}-{3:3}, at: user_get_super+0xd9/0x190 #1: ffff8880084bc380 (&sbi->cp_rwsem){++++}-{3:3}, at: f2fs_quota_sync+0x3e/0x300 [f2fs] #2: ffff8880084bcde8 (&sbi->quota_sem){.+.+}-{3:3}, at: f2fs_quota_sync+0x59/0x300 [f2fs]
stack backtrace: CPU: 6 PID: 8606 Comm: repquota Not tainted 5.14.0-rc1 #69 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 Call Trace: dump_stack_lvl+0xce/0x134 dump_stack+0x17/0x20 print_circular_bug.isra.0.cold+0x239/0x253 check_noncircular+0x1be/0x1f0 check_prev_add+0xdc/0xb30 validate_chain+0xa67/0xb20 __lock_acquire+0x648/0x10b0 lock_acquire+0x128/0x470 down_write+0x39/0xc0 f2fs_quota_sync+0x207/0x300 [f2fs] do_quotactl+0xaff/0xb30 __x64_sys_quotactl+0x23a/0x4e0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f883b0b4efe
The root cause is ABBA deadlock of inode lock and cp_rwsem, reorder locks in f2fs_quota_sync() as below to fix this issue: - lock inode - lock cp_rwsem - lock quota_sem
Fixes: db6ec53b7e03 ("f2fs: add a rw_sem to cover quota flag changes") Signed-off-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/super.c | 84 ++++++++++++++++++++++++++++--------------------- 1 file changed, 48 insertions(+), 36 deletions(-)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 6d904dc9bd19..41bf656658ba 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -1994,6 +1994,33 @@ static int f2fs_enable_quotas(struct super_block *sb) return 0; }
+static int f2fs_quota_sync_file(struct f2fs_sb_info *sbi, int type) +{ + struct quota_info *dqopt = sb_dqopt(sbi->sb); + struct address_space *mapping = dqopt->files[type]->i_mapping; + int ret = 0; + + ret = dquot_writeback_dquots(sbi->sb, type); + if (ret) + goto out; + + ret = filemap_fdatawrite(mapping); + if (ret) + goto out; + + /* if we are using journalled quota */ + if (is_journalled_quota(sbi)) + goto out; + + ret = filemap_fdatawait(mapping); + + truncate_inode_pages(&dqopt->files[type]->i_data, 0); +out: + if (ret) + set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR); + return ret; +} + int f2fs_quota_sync(struct super_block *sb, int type) { struct f2fs_sb_info *sbi = F2FS_SB(sb); @@ -2001,57 +2028,42 @@ int f2fs_quota_sync(struct super_block *sb, int type) int cnt; int ret;
- /* - * do_quotactl - * f2fs_quota_sync - * down_read(quota_sem) - * dquot_writeback_dquots() - * f2fs_dquot_commit - * block_operation - * down_read(quota_sem) - */ - f2fs_lock_op(sbi); - - down_read(&sbi->quota_sem); - ret = dquot_writeback_dquots(sb, type); - if (ret) - goto out; - /* * Now when everything is written we can discard the pagecache so * that userspace sees the changes. */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { - struct address_space *mapping;
if (type != -1 && cnt != type) continue; - if (!sb_has_quota_active(sb, cnt)) - continue;
- mapping = dqopt->files[cnt]->i_mapping; + if (!sb_has_quota_active(sb, type)) + return 0;
- ret = filemap_fdatawrite(mapping); - if (ret) - goto out; + inode_lock(dqopt->files[cnt]);
- /* if we are using journalled quota */ - if (is_journalled_quota(sbi)) - continue; + /* + * do_quotactl + * f2fs_quota_sync + * down_read(quota_sem) + * dquot_writeback_dquots() + * f2fs_dquot_commit + * block_operation + * down_read(quota_sem) + */ + f2fs_lock_op(sbi); + down_read(&sbi->quota_sem);
- ret = filemap_fdatawait(mapping); - if (ret) - set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR); + ret = f2fs_quota_sync_file(sbi, cnt); + + up_read(&sbi->quota_sem); + f2fs_unlock_op(sbi);
- inode_lock(dqopt->files[cnt]); - truncate_inode_pages(&dqopt->files[cnt]->i_data, 0); inode_unlock(dqopt->files[cnt]); + + if (ret) + break; } -out: - if (ret) - set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR); - up_read(&sbi->quota_sem); - f2fs_unlock_op(sbi); return ret; }