gfs2: Get rid of GLF_INVALIDATE_IN_PROGRESS

Get rid of the GLF_INVALIDATE_IN_PROGRESS flag: it was originally used
to indicate to add_to_queue() that the ->go_sync() and ->go_invalid()
operations were in progress, but as we have established in commit "gfs2:
Fix LM_FLAG_TRY* logic in add_to_queue", add_to_queue() has no need to
know.

Commit d99724c describes a race in which GLF_INVALIDATE_IN_PROGRESS
is used to serialize two processes which are both in do_xmote() at the
same time.  That analysis is wrong: the serialization happens via the
GLF_LOCK flag, which ensures that at most one glock operation can be
active at any time.

Fixes: d99724c ("gfs2: Close timing window with GLF_INVALIDATE_IN_PROGRESS")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Andrew Price <anprice@redhat.com>

Author: Andreas Gruenbacher

fs/gfs2/glock.c

@@ -703,17 +703,6 @@ __acquires(&gl->gl_lockref.lock)
 
 	GLOCK_BUG_ON(gl, gl->gl_state == target);
 	GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
-	if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
-	    glops->go_inval) {
-		/*
-		 * If another process is already doing the invalidate, let that
-		 * finish first.  The glock state machine will get back to this
-		 * holder again later.
-		 */
-		if (test_and_set_bit(GLF_INVALIDATE_IN_PROGRESS,
-				     &gl->gl_flags))
-			return;
-	}
 	if (!glops->go_inval || !glops->go_sync)
 		goto skip_inval;
 
@@ -732,7 +721,7 @@ __acquires(&gl->gl_lockref.lock)
 		goto skip_inval;
 	}
 
-	if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags)) {
+	if (target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) {
 		/*
 		 * The call to go_sync should have cleared out the ail list.
 		 * If there are still items, we have a problem. We ought to
@@ -747,7 +736,6 @@ __acquires(&gl->gl_lockref.lock)
 			gfs2_dump_glock(NULL, gl, true);
 		}
 		glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
-		clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 	}
 	spin_lock(&gl->gl_lockref.lock);
 
@@ -2316,8 +2304,6 @@ static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
 		*p++ = 'y';
 	if (test_bit(GLF_LFLUSH, gflags))
 		*p++ = 'f';
-	if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
-		*p++ = 'i';
 	if (test_bit(GLF_PENDING_REPLY, gflags))
 		*p++ = 'R';
 	if (test_bit(GLF_HAVE_REPLY, gflags))

fs/gfs2/incore.h

@@ -319,7 +319,6 @@ enum {
 	GLF_DEMOTE_IN_PROGRESS		= 5,
 	GLF_DIRTY			= 6,
 	GLF_LFLUSH			= 7,
-	GLF_INVALIDATE_IN_PROGRESS	= 8,
 	GLF_HAVE_REPLY			= 9,
 	GLF_INITIAL			= 10,
 	GLF_HAVE_FROZEN_REPLY		= 11,

fs/gfs2/trace_gfs2.h

@@ -52,7 +52,6 @@
 	{(1UL << GLF_DEMOTE_IN_PROGRESS),	"p" },		\
 	{(1UL << GLF_DIRTY),			"y" },		\
 	{(1UL << GLF_LFLUSH),			"f" },		\
-	{(1UL << GLF_INVALIDATE_IN_PROGRESS),	"i" },		\
 	{(1UL << GLF_PENDING_REPLY),		"R" },		\
 	{(1UL << GLF_HAVE_REPLY),		"r" },		\
 	{(1UL << GLF_INITIAL),			"a" },		\