From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933923AbaLBT2I (ORCPT ); Tue, 2 Dec 2014 14:28:08 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:47073 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933882AbaLBT1P (ORCPT ); Tue, 2 Dec 2014 14:27:15 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mikulas Patocka , Mike Snitzer , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 045/121] dm bufio: change __GFP_IO to __GFP_FS in shrinker callbacks Date: Tue, 2 Dec 2014 11:18:44 -0800 Message-Id: <1417548000-1794-46-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1417548000-1794-1-git-send-email-kamal@canonical.com> References: <1417548000-1794-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 9d28eb12447ee08bb5d1e8bb3195cf20e1ecd1c0 upstream. The shrinker uses gfp flags to indicate what kind of operation can the driver wait for. If __GFP_IO flag is present, the driver can wait for block I/O operations, if __GFP_FS flag is present, the driver can wait on operations involving the filesystem. dm-bufio tested for __GFP_IO. However, dm-bufio can run on a loop block device that makes calls into the filesystem. If __GFP_IO is present and __GFP_FS isn't, dm-bufio could still block on filesystem operations if it runs on a loop block device. The change from __GFP_IO to __GFP_FS supposedly fixes one observed (though unreproducible) deadlock involving dm-bufio and loop device. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Kamal Mostafa --- drivers/md/dm-bufio.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index a42efc7..140be2d 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1418,9 +1418,9 @@ static void drop_buffers(struct dm_bufio_client *c) /* * Test if the buffer is unused and too old, and commit it. - * At if noio is set, we must not do any I/O because we hold - * dm_bufio_clients_lock and we would risk deadlock if the I/O gets rerouted to - * different bufio client. + * And if GFP_NOFS is used, we must not do any I/O because we hold + * dm_bufio_clients_lock and we would risk deadlock if the I/O gets + * rerouted to different bufio client. */ static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp, unsigned long max_jiffies) @@ -1428,7 +1428,7 @@ static int __cleanup_old_buffer(struct dm_buffer *b, gfp_t gfp, if (jiffies - b->last_accessed < max_jiffies) return 0; - if (!(gfp & __GFP_IO)) { + if (!(gfp & __GFP_FS)) { if (test_bit(B_READING, &b->state) || test_bit(B_WRITING, &b->state) || test_bit(B_DIRTY, &b->state)) @@ -1470,7 +1470,7 @@ dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) unsigned long freed; c = container_of(shrink, struct dm_bufio_client, shrinker); - if (sc->gfp_mask & __GFP_IO) + if (sc->gfp_mask & __GFP_FS) dm_bufio_lock(c); else if (!dm_bufio_trylock(c)) return SHRINK_STOP; @@ -1487,7 +1487,7 @@ dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc) unsigned long count; c = container_of(shrink, struct dm_bufio_client, shrinker); - if (sc->gfp_mask & __GFP_IO) + if (sc->gfp_mask & __GFP_FS) dm_bufio_lock(c); else if (!dm_bufio_trylock(c)) return 0; -- 1.9.1