| From | Greg Kroah-Hartman <> | Subject | [ 074/218] nbd: clear waiting_queue on shutdown | Date | Fri, 28 Sep 2012 13:14:51 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Paul Clements <paul.clements@steeleye.com>
commit fded4e090c60100d709318896c79816d68d5b47d upstream.
Fix a serious but uncommon bug in nbd which occurs when there is heavy I/O going to the nbd device while, at the same time, a failure (server, network) or manual disconnect of the nbd connection occurs.
There is a small window between the time that the nbd_thread is stopped and the socket is shutdown where requests can continue to be queued to nbd's internal waiting_queue. When this happens, those requests are never completed or freed.
The fix is to clear the waiting_queue on shutdown of the nbd device, in the same way that the nbd request queue (queue_head) is already being cleared.
Signed-off-by: Paul Clements <paul.clements@steeleye.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/block/nbd.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -445,6 +445,14 @@ static void nbd_clear_que(struct nbd_dev req->errors++; nbd_end_request(req); } + + while (!list_empty(&nbd->waiting_queue)) { + req = list_entry(nbd->waiting_queue.next, struct request, + queuelist); + list_del_init(&req->queuelist); + req->errors++; + nbd_end_request(req); + } } @@ -594,6 +602,7 @@ static int __nbd_ioctl(struct block_devi nbd->file = NULL; nbd_clear_que(nbd); BUG_ON(!list_empty(&nbd->queue_head)); + BUG_ON(!list_empty(&nbd->waiting_queue)); if (file) fput(file); return 0;
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