[PATCH v2 0/2] fix two issue about quota

[PATCH v2 0/2] fix two issue about quota

[Ye Bin]

Jan Kara (1):
  quota: Properly disable quotas when add_dquot_ref() fails

Ye Bin (1):
  quota: fix warning in dqgrab()

 fs/quota/dquot.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

-- 
2.31.1

[PATCH v2 1/2] quota: Properly disable quotas when add_dquot_ref() fails

[Ye Bin]

From: Jan Kara <jack@suse.cz>

When add_dquot_ref() fails (usually due to IO error or ENOMEM), we want
to disable quotas we are trying to enable. However dquot_disable() call
was passed just the flags we are enabling so in case flags ==
DQUOT_USAGE_ENABLED dquot_disable() call will just fail with EINVAL
instead of properly disabling quotas. Fix the problem by always passing
DQUOT_LIMITS_ENABLED | DQUOT_USAGE_ENABLED to dquot_disable() in this
case.

Reported-and-tested-by: Ye Bin <yebin10@huawei.com>
Reported-by: syzbot+e633c79ceaecbf479854@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/quota/dquot.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index ffd40dc3e4e9..6beceed34e08 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2420,7 +2420,8 @@ int dquot_load_quota_sb(struct super_block *sb, int type, int format_id,
 
 	error = add_dquot_ref(sb, type);
 	if (error)
-		dquot_disable(sb, type, flags);
+		dquot_disable(sb, type,
+			      DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
 
 	return error;
 out_fmt:
-- 
2.31.1

[PATCH v2 2/2] quota: fix warning in dqgrab()

[Ye Bin]

There's issue as follows when do fault injection:
WARNING: CPU: 1 PID: 14870 at include/linux/quotaops.h:51 dquot_disable+0x13b7/0x18c0
Modules linked in:
CPU: 1 PID: 14870 Comm: fsconfig Not tainted 6.3.0-next-20230505-00006-g5107a9c821af-dirty #541
RIP: 0010:dquot_disable+0x13b7/0x18c0
RSP: 0018:ffffc9000acc79e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88825e41b980
RDX: 0000000000000000 RSI: ffff88825e41b980 RDI: 0000000000000002
RBP: ffff888179f68000 R08: ffffffff82087ca7 R09: 0000000000000000
R10: 0000000000000001 R11: ffffed102f3ed026 R12: ffff888179f68130
R13: ffff888179f68110 R14: dffffc0000000000 R15: ffff888179f68118
FS:  00007f450a073740(0000) GS:ffff88882fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe96f2efd8 CR3: 000000025c8ad000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dquot_load_quota_sb+0xd53/0x1060
 dquot_resume+0x172/0x230
 ext4_reconfigure+0x1dc6/0x27b0
 reconfigure_super+0x515/0xa90
 __x64_sys_fsconfig+0xb19/0xd20
 do_syscall_64+0x39/0xb0
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Above issue may happens as follows:
ProcessA              ProcessB                    ProcessC
sys_fsconfig
  vfs_fsconfig_locked
   reconfigure_super
     ext4_remount
      dquot_suspend -> suspend all type quota

                 sys_fsconfig
                  vfs_fsconfig_locked
                    reconfigure_super
                     ext4_remount
                      dquot_resume
                       ret = dquot_load_quota_sb
                        add_dquot_ref
                                           do_open  -> open file O_RDWR
                                            vfs_open
                                             do_dentry_open
                                              get_write_access
                                               atomic_inc_unless_negative(&inode->i_writecount)
                                              ext4_file_open
                                               dquot_file_open
                                                dquot_initialize
                                                  __dquot_initialize
                                                   dqget
						    atomic_inc(&dquot->dq_count);

                          __dquot_initialize
                           __dquot_initialize
                            dqget
                             if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
                               ext4_acquire_dquot
			        -> Return error DQ_ACTIVE_B flag isn't set
                         dquot_disable
			  invalidate_dquots
			   if (atomic_read(&dquot->dq_count))
	                    dqgrab
			     WARN_ON_ONCE(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
	                      -> Trigger warning

In the above scenario, 'dquot->dq_flags' has no DQ_ACTIVE_B is normal when
dqgrab().
To solve above issue just replace the dqgrab() use in invalidate_dquots() with
atomic_inc(&dquot->dq_count).

Signed-off-by: Ye Bin <yebin10@huawei.com>
---
 fs/quota/dquot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 6beceed34e08..e3e4f4047657 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -555,7 +555,7 @@ static void invalidate_dquots(struct super_block *sb, int type)
 			continue;
 		/* Wait for dquot users */
 		if (atomic_read(&dquot->dq_count)) {
-			dqgrab(dquot);
+			atomic_inc(&dquot->dq_count);
 			spin_unlock(&dq_list_lock);
 			/*
 			 * Once dqput() wakes us up, we know it's time to free
-- 
2.31.1

Re: [PATCH v2 0/2] fix two issue about quota

[Jan Kara]

On Mon 05-06-23 22:07:29, Ye Bin wrote:
> Jan Kara (1):
>   quota: Properly disable quotas when add_dquot_ref() fails
> 
> Ye Bin (1):
>   quota: fix warning in dqgrab()
> 
>  fs/quota/dquot.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Thanks! I've queued the fixes into my tree.

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR