5 files changed, 61 insertions, 4 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index ad8e121427c..3984e47d1d3 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -684,10 +684,11 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 	gl = search_bucket(hash, sdp, &name);
 	read_unlock(gl_lock_addr(hash));
 
-	if (gl || !create) {
-		*glp = gl;
+	*glp = gl;
+	if (gl)
 		return 0;
-	}
+	if (!create)
+		return -ENOENT;
 
 	gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 	if (!gl)
diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index a9b7d3a6008..f34bc7093dd 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -447,3 +447,15 @@ const struct gfs2_glock_operations gfs2_journal_glops = {
 	.go_type = LM_TYPE_JOURNAL,
 };
 
+const struct gfs2_glock_operations *gfs2_glops_list[] = {
+	[LM_TYPE_META] = &gfs2_meta_glops,
+	[LM_TYPE_INODE] = &gfs2_inode_glops,
+	[LM_TYPE_RGRP] = &gfs2_rgrp_glops,
+	[LM_TYPE_NONDISK] = &gfs2_trans_glops,
+	[LM_TYPE_IOPEN] = &gfs2_iopen_glops,
+	[LM_TYPE_FLOCK] = &gfs2_flock_glops,
+	[LM_TYPE_NONDISK] = &gfs2_nondisk_glops,
+	[LM_TYPE_QUOTA] = &gfs2_quota_glops,
+	[LM_TYPE_JOURNAL] = &gfs2_journal_glops,
+};
+
diff --git a/fs/gfs2/glops.h b/fs/gfs2/glops.h
index a1d9b5b024e..b3aa2e3210f 100644
--- a/fs/gfs2/glops.h
+++ b/fs/gfs2/glops.h
@@ -21,5 +21,6 @@ extern const struct gfs2_glock_operations gfs2_flock_glops;
 extern const struct gfs2_glock_operations gfs2_nondisk_glops;
 extern const struct gfs2_glock_operations gfs2_quota_glops;
 extern const struct gfs2_glock_operations gfs2_journal_glops;
+extern const struct gfs2_glock_operations *gfs2_glops_list[];
 
 #endif /* __GLOPS_DOT_H__ */
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 789953a2b6a..a068ac940de 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -839,7 +839,7 @@ static void gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 	const unsigned int sects_per_blk = sdp->sd_sb.sb_bsize /
 					   bdev_hardsect_size(sb->s_bdev);
 	u64 blk;
-	sector_t start;
+	sector_t start = 0;
 	sector_t nr_sects = 0;
 	int rv;
 	unsigned int x;
diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index 4d284d14980..7655f5025fe 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -24,6 +24,7 @@
 #include "glock.h"
 #include "quota.h"
 #include "util.h"
+#include "glops.h"
 
 static ssize_t id_show(struct gfs2_sbd *sdp, char *buf)
 {
@@ -171,6 +172,46 @@ static ssize_t quota_refresh_group_store(struct gfs2_sbd *sdp, const char *buf,
 	return len;
 }
 
+static ssize_t demote_rq_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
+{
+	struct gfs2_glock *gl;
+	const struct gfs2_glock_operations *glops;
+	unsigned int glmode;
+	unsigned int gltype;
+	unsigned long long glnum;
+	char mode[16];
+	int rv;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	rv = sscanf(buf, "%u:%llu %15s", &gltype, &glnum,
+		    mode);
+	if (rv != 3)
+		return -EINVAL;
+
+	if (strcmp(mode, "EX") == 0)
+		glmode = LM_ST_UNLOCKED;
+	else if ((strcmp(mode, "CW") == 0) || (strcmp(mode, "DF") == 0))
+		glmode = LM_ST_DEFERRED;
+	else if ((strcmp(mode, "PR") == 0) || (strcmp(mode, "SH") == 0))
+		glmode = LM_ST_SHARED;
+	else
+		return -EINVAL;
+
+	if (gltype > LM_TYPE_JOURNAL)
+		return -EINVAL;
+	glops = gfs2_glops_list[gltype];
+	if (glops == NULL)
+		return -EINVAL;
+	rv = gfs2_glock_get(sdp, glnum, glops, 0, &gl);
+	if (rv)
+		return rv;
+	gfs2_glock_cb(gl, glmode);
+	gfs2_glock_put(gl);
+	return len;
+}
+
 struct gfs2_attr {
 	struct attribute attr;
 	ssize_t (*show)(struct gfs2_sbd *, char *);
@@ -189,6 +230,7 @@ GFS2_ATTR(statfs_sync,         0200, NULL,          statfs_sync_store);
 GFS2_ATTR(quota_sync,          0200, NULL,          quota_sync_store);
 GFS2_ATTR(quota_refresh_user,  0200, NULL,          quota_refresh_user_store);
 GFS2_ATTR(quota_refresh_group, 0200, NULL,          quota_refresh_group_store);
+GFS2_ATTR(demote_rq,           0200, NULL,	    demote_rq_store);
 
 static struct attribute *gfs2_attrs[] = {
 	&gfs2_attr_id.attr,
@@ -200,6 +242,7 @@ static struct attribute *gfs2_attrs[] = {
 	&gfs2_attr_quota_sync.attr,
 	&gfs2_attr_quota_refresh_user.attr,
 	&gfs2_attr_quota_refresh_group.attr,
+	&gfs2_attr_demote_rq.attr,
 	NULL,
 };