quota: fix warning in dqgrab()

In the Linux kernel, the following vulnerability has been resolved:

quota: fix warning in dqgrab()

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).