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Date: Fri, 18 Jul 2014 11:37:38 +0100 From: Steven Whitehouse <swhiteho@...hat.com> To: linux-kernel@...r.kernel.org, cluster-devel@...hat.com Cc: Bob Peterson <rpeterso@...hat.com>, Steven Whitehouse <swhiteho@...hat.com> Subject: [PATCH 1/8] GFS2: Only wait for demote when last holder is dequeued From: Bob Peterson <rpeterso@...hat.com> Function gfs2_glock_dq_wait is supposed to dequeue a glock and then wait for the lock to be demoted. The problem is, if this is a shared lock, its demote will depend on the other holders, which means you might end up waiting forever because the other process is blocked. This problem is especially apparent when dealing with nested flocks. Signed-off-by: Bob Peterson <rpeterso@...hat.com> Signed-off-by: Steven Whitehouse <swhiteho@...hat.com> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index c355f73..278fae5 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1128,7 +1128,9 @@ void gfs2_glock_dq_wait(struct gfs2_holder *gh) struct gfs2_glock *gl = gh->gh_gl; gfs2_glock_dq(gh); might_sleep(); - wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE); + if (!find_first_holder(gl)) + wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, + TASK_UNINTERRUPTIBLE); } /** -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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