On 05/08/13 22:16, Dave Chinner wrote:
xfs: avoid nesting transactions in xfs_qm_scall_setqlim()
From: Dave Chinner<dchinner@xxxxxxxxxx>
Lockdep reports:
=============================================
[ INFO: possible recursive locking detected ]
3.9.0+ #3 Not tainted
---------------------------------------------
setquota/28368 is trying to acquire lock:
(sb_internal){++++.?}, at: [<c11e8846>] xfs_trans_alloc+0x26/0x50
but task is already holding lock:
(sb_internal){++++.?}, at: [<c11e8846>] xfs_trans_alloc+0x26/0x50
from xfs_qm_scall_setqlim()->xfs_dqread() when a dquot needs to be
allocated.
xfs_qm_scall_setqlim() is starting a transaction and then not
passing it into xfs_qm_dqet() and so it starts it's own transaction
when allocating the dquot. Splat!
Fix this by not allocating the dquot in xfs_qm_scall_setqlim()
inside the setqlim transaction. This requires getting the dquot
first (and allocating it if necessary) then dropping and relocking
the dquot before joining it to the setqlim transaction.
Reported-by: Michael L. Semon<mlsemon35@xxxxxxxxx>
Signed-off-by: Dave Chinner<dchinner@xxxxxxxxxx>
---
fs/xfs/xfs_qm_syscalls.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
Looks good.
Reviewed-by: Mark Tinguely <tinguely@xxxxxxx>
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