[GFS2] Remove local exclusive glock mode

Here is a patch for GFS2 to remove the local exclusive flag. In
the places it was used, mutex's are always held earlier in the
call path, so it appears redundant in the LM_ST_SHARED case.

Also, the GFS2 holders were setting local exclusive in any case where
the requested lock was LM_ST_EXCLUSIVE. So the other places in the glock
code where the flag was tested have been replaced with tests for the
lock state being LM_ST_EXCLUSIVE in order to ensure the logic is the
same as before (i.e. LM_ST_EXCLUSIVE is always locally exclusive as well
as globally exclusive).
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glock.c

@@ -391,10 +391,6 @@ void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 	gh->gh_flags = flags;
 	gh->gh_error = 0;
 	gh->gh_iflags = 0;
-
-	if (gh->gh_state == LM_ST_EXCLUSIVE)
-		gh->gh_flags |= GL_LOCAL_EXCL;
-
 	gfs2_glock_hold(gl);
 }
 
@@ -412,9 +408,6 @@ void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *
 {
 	gh->gh_state = state;
 	gh->gh_flags = flags;
-	if (gh->gh_state == LM_ST_EXCLUSIVE)
-		gh->gh_flags |= GL_LOCAL_EXCL;
-
 	gh->gh_iflags &= 1 << HIF_ALLOCED;
 	gh->gh_ip = (unsigned long)__builtin_return_address(0);
 }
@@ -557,11 +550,11 @@ static int rq_promote(struct gfs2_holder *gh)
 		set_bit(GLF_LOCK, &gl->gl_flags);
 	} else {
 		struct gfs2_holder *next_gh;
-		if (gh->gh_flags & GL_LOCAL_EXCL)
+		if (gh->gh_state == LM_ST_EXCLUSIVE)
 			return 1;
 		next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
 				     gh_list);
-		if (next_gh->gh_flags & GL_LOCAL_EXCL)
+		if (next_gh->gh_state == LM_ST_EXCLUSIVE)
 			 return 1;
 	}
 
@@ -1363,10 +1356,7 @@ static int glock_compare(const void *arg_a, const void *arg_b)
 		return 1;
 	if (a->ln_number < b->ln_number)
 		return -1;
-	if (gh_a->gh_state == LM_ST_SHARED && gh_b->gh_state == LM_ST_EXCLUSIVE)
-		return 1;
-	if (!(gh_a->gh_flags & GL_LOCAL_EXCL) && (gh_b->gh_flags & GL_LOCAL_EXCL))
-		return 1;
+	BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
 	return 0;
 }
 

fs/gfs2/glock.h

@@ -20,7 +20,6 @@
 #define LM_FLAG_ANY		0x00000008
 #define LM_FLAG_PRIORITY	0x00000010 */
 
-#define GL_LOCAL_EXCL		0x00000020
 #define GL_ASYNC		0x00000040
 #define GL_EXACT		0x00000080
 #define GL_SKIP			0x00000100

fs/gfs2/glops.c

@@ -295,7 +295,7 @@ static int inode_go_lock(struct gfs2_holder *gh)
 
 	if ((ip->i_di.di_flags & GFS2_DIF_TRUNC_IN_PROG) &&
 	    (gl->gl_state == LM_ST_EXCLUSIVE) &&
-	    (gh->gh_flags & GL_LOCAL_EXCL))
+	    (gh->gh_state == LM_ST_EXCLUSIVE))
 		error = gfs2_truncatei_resume(ip);
 
 	return error;

fs/gfs2/ops_export.c

@@ -216,8 +216,7 @@ static struct dentry *gfs2_get_dentry(struct super_block *sb, void *inum_obj)
 	}
 
 	error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
-				  LM_ST_SHARED, LM_FLAG_ANY | GL_LOCAL_EXCL,
-				  &i_gh);
+				  LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 	if (error)
 		return ERR_PTR(error);
 

fs/gfs2/super.c

@@ -354,8 +354,7 @@ int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
 	mutex_lock(&sdp->sd_jindex_mutex);
 
 	for (;;) {
-		error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED,
-					   GL_LOCAL_EXCL, ji_gh);
+		error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, ji_gh);
 		if (error)
 			break;
 
@@ -524,8 +523,7 @@ int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
 	struct gfs2_log_header_host head;
 	int error;
 
-	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED,
-				   GL_LOCAL_EXCL, &t_gh);
+	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED, 0, &t_gh);
 	if (error)
 		return error;
 
@@ -578,9 +576,8 @@ int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
 	gfs2_quota_sync(sdp);
 	gfs2_statfs_sync(sdp);
 
-	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED,
-				GL_LOCAL_EXCL | GL_NOCACHE,
-				&t_gh);
+	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED, GL_NOCACHE,
+				   &t_gh);
 	if (error && !test_bit(SDF_SHUTDOWN, &sdp->sd_flags))
 		return error;