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Commit 0809f6ec authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

GFS2: Fix recovery stuck bug (try #2) 



This is a clean up of the code which deals with LM_FLAG_NOEXP
which aims to remove any possible race conditions by using
gl_spin to cover the gap between testing for the LM_FLAG_NOEXP
and the GL_FROZEN flag.

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent c639d5d8

fs/gfs2/glock.c

+39 −7
Original line number Diff line number Diff line
@@ -1063,6 +1063,9 @@ int gfs2_glock_nq(struct gfs2_holder *gh) 


	spin_lock(&gl->gl_spin);

	add_to_queue(gh);

	if ((LM_FLAG_NOEXP & gh->gh_flags) &&

	    test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))

		set_bit(GLF_REPLY_PENDING, &gl->gl_flags);

	run_queue(gl, 1);

	spin_unlock(&gl->gl_spin);
@@ -1319,6 +1322,36 @@ void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state) 
		gfs2_glock_put(gl);

}



/**

 * gfs2_should_freeze - Figure out if glock should be frozen

 * @gl: The glock in question

 *

 * Glocks are not frozen if (a) the result of the dlm operation is

 * an error, (b) the locking operation was an unlock operation or

 * (c) if there is a "noexp" flagged request anywhere in the queue

 *

 * Returns: 1 if freezing should occur, 0 otherwise

 */



static int gfs2_should_freeze(const struct gfs2_glock *gl)

{

	const struct gfs2_holder *gh;



	if (gl->gl_reply & ~LM_OUT_ST_MASK)

		return 0;

	if (gl->gl_target == LM_ST_UNLOCKED)

		return 0;



	list_for_each_entry(gh, &gl->gl_holders, gh_list) {

		if (test_bit(HIF_HOLDER, &gh->gh_iflags))

			continue;

		if (LM_FLAG_NOEXP & gh->gh_flags)

			return 0;

	}



	return 1;

}



/**

 * gfs2_glock_complete - Callback used by locking

 * @gl: Pointer to the glock
@@ -1329,19 +1362,18 @@ void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state) 
void gfs2_glock_complete(struct gfs2_glock *gl, int ret)

{

	struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;



	gl->gl_reply = ret;



	if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {

		struct gfs2_holder *gh;

		spin_lock(&gl->gl_spin);

		gh = find_first_waiter(gl);

		if ((!(gh && (gh->gh_flags & LM_FLAG_NOEXP)) &&

		     (gl->gl_target != LM_ST_UNLOCKED)) ||

		    ((ret & ~LM_OUT_ST_MASK) != 0))

		if (gfs2_should_freeze(gl)) {

			set_bit(GLF_FROZEN, &gl->gl_flags);

			spin_unlock(&gl->gl_spin);

		if (test_bit(GLF_FROZEN, &gl->gl_flags))

			return;

		}

		spin_unlock(&gl->gl_spin);

	}

	set_bit(GLF_REPLY_PENDING, &gl->gl_flags);

	gfs2_glock_hold(gl);

	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)