Hi,
On 19/11/15 18:42, Bob Peterson wrote:
This patch changes function gfs2_clear_inode() so that instead
of calling gfs2_glock_put directly() most of the time, it queues
the glock to the delayed work queue. That avoids a possible
deadlock where it calls dlm during a fence operation:
dlm waits for a fence operation, the fence operation waits for
memory, the shrinker waits for gfs2 to free an inode from memory,
but gfs2 waits for dlm.
Signed-off-by: Bob Peterson <rpete...@redhat.com>
---
fs/gfs2/glock.c | 34 +++++++++++++++++-----------------
fs/gfs2/glock.h | 1 +
fs/gfs2/super.c | 5 ++++-
3 files changed, 22 insertions(+), 18 deletions(-)
[snip]
Most of the patch seems to just rename the workqueue which makes it
tricky to spot the other changes. However, the below code seems to be
the new bit..
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 9d5c3f7..46e5004 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -24,6 +24,7 @@
#include <linux/crc32.h>
#include <linux/time.h>
#include <linux/wait.h>
+#include <linux/workqueue.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/kernel.h>
@@ -1614,7 +1615,9 @@ out:
ip->i_gl->gl_object = NULL;
flush_delayed_work(&ip->i_gl->gl_work);
gfs2_glock_add_to_lru(ip->i_gl);
- gfs2_glock_put(ip->i_gl);
+ if (queue_delayed_work(gfs2_glock_workqueue,
+ &ip->i_gl->gl_work, 0) == 0)
+ gfs2_glock_put(ip->i_gl);
ip->i_gl = NULL;
if (ip->i_iopen_gh.gh_gl) {
ip->i_iopen_gh.gh_gl->gl_object = NULL;
which replaces a put with a queue & put if the queue fails (due to it
being already on the queue) which doesn't look quite right to be since
if calling gfs2_glock_put() was not safe before, then calling it
conditionally like this is still no safer I think?
Steve.
