Commit 0c23e241 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Fix LM_FLAG_TRY* logic in add_to_queue 



The logic in add_to_queue() for determining whether a LM_FLAG_TRY or
LM_FLAG_TRY_1CB holder should be queued does not make any sense: we are
interested in wether or not the new operation will block behind an
existing or future holder in the queue, but the current code checks for
ongoing locking or ->go_inval() operations, which has little to do with
that.

Replace that code with something more sensible, remove the incorrect
add_to_queue() function annotations, remove the similarly misguided
do_error(gl, 0) call in do_xmote(), and add a missing comment to the
same call in do_promote().

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: default avatarAndrew Price <anprice@redhat.com>
parent 2b813a72

fs/gfs2/glock.c

+24 −23
Original line number Diff line number Diff line
@@ -502,7 +502,7 @@ static bool do_promote(struct gfs2_glock *gl) 
			 */

			if (list_is_first(&gh->gh_list, &gl->gl_holders))

				return false;

			do_error(gl, 0);

			do_error(gl, 0); /* Fail queued try locks */

			break;

		}

		set_bit(HIF_HOLDER, &gh->gh_iflags);
@@ -713,7 +713,6 @@ __acquires(&gl->gl_lockref.lock) 
		if (test_and_set_bit(GLF_INVALIDATE_IN_PROGRESS,

				     &gl->gl_flags))

			return;

		do_error(gl, 0); /* Fail queued try locks */

	}

	if (!glops->go_inval && !glops->go_sync)

		goto skip_inval;
@@ -1459,6 +1458,24 @@ void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...) 
	va_end(args);

}



static bool gfs2_should_queue_trylock(struct gfs2_glock *gl,

				      struct gfs2_holder *gh)

{

	struct gfs2_holder *current_gh, *gh2;



	current_gh = find_first_holder(gl);

	if (current_gh && !may_grant(gl, current_gh, gh))

		return false;



	list_for_each_entry(gh2, &gl->gl_holders, gh_list) {

		if (test_bit(HIF_HOLDER, &gh2->gh_iflags))

			continue;

		if (!(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))

			return false;

	}

	return true;

}



static inline bool pid_is_meaningful(const struct gfs2_holder *gh)

{

        if (!(gh->gh_flags & GL_NOPID))
@@ -1477,27 +1494,20 @@ static inline bool pid_is_meaningful(const struct gfs2_holder *gh) 
 */



static inline void add_to_queue(struct gfs2_holder *gh)

__releases(&gl->gl_lockref.lock)

__acquires(&gl->gl_lockref.lock)

{

	struct gfs2_glock *gl = gh->gh_gl;

	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;

	struct gfs2_holder *gh2;

	int try_futile = 0;



	GLOCK_BUG_ON(gl, gh->gh_owner_pid == NULL);

	if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))

		GLOCK_BUG_ON(gl, true);



	if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {

		if (test_bit(GLF_LOCK, &gl->gl_flags)) {

			struct gfs2_holder *current_gh;



			current_gh = find_first_holder(gl);

			try_futile = !may_grant(gl, current_gh, gh);

		}

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

			goto fail;

	if ((gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&

	    !gfs2_should_queue_trylock(gl, gh)) {

		gh->gh_error = GLR_TRYFAILED;

		gfs2_holder_wake(gh);

		return;

	}



	list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
@@ -1509,15 +1519,6 @@ __acquires(&gl->gl_lockref.lock) 
			continue;

		goto trap_recursive;

	}

	list_for_each_entry(gh2, &gl->gl_holders, gh_list) {

		if (try_futile &&

		    !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {

fail:

			gh->gh_error = GLR_TRYFAILED;

			gfs2_holder_wake(gh);

			return;

		}

	}

	trace_gfs2_glock_queue(gh, 1);

	gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);

	gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);