1 files changed, 43 insertions, 0 deletions

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,
 };