Introduce md_cluster_info

md_cluster_info stores the cluster information in the MD device.

The join() is called when mddev detects it is a clustered device.
The main responsibilities are:
	1. Setup a DLM lockspace
	2. Setup all initial locks such as super block locks and bitmap lock (will come later)

The leave() clears up the lockspace and all the locks held.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

4 files changed, 80 insertions, 4 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 3a5767968ba0..e2aacca46911 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -433,6 +433,7 @@ void bitmap_update_sb(struct bitmap *bitmap)
         /* This might have been changed by a reshape */
         sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
         sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);
+        sb->nodes = cpu_to_le32(bitmap->mddev->bitmap_info.nodes);
         sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
                                            bitmap_info.space);
         kunmap_atomic(sb);
@@ -544,6 +545,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
         bitmap_super_t *sb;
         unsigned long chunksize, daemon_sleep, write_behind;
         unsigned long long events;
+        int nodes = 0;
         unsigned long sectors_reserved = 0;
         int err = -EINVAL;
         struct page *sb_page;
@@ -583,6 +585,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
         daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
         write_behind = le32_to_cpu(sb->write_behind);
         sectors_reserved = le32_to_cpu(sb->sectors_reserved);
+        nodes = le32_to_cpu(sb->nodes);
 
         /* verify that the bitmap-specific fields are valid */
         if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
@@ -643,6 +646,7 @@ out_no_sb:
         bitmap->mddev->bitmap_info.chunksize = chunksize;
         bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
         bitmap->mddev->bitmap_info.max_write_behind = write_behind;
+        bitmap->mddev->bitmap_info.nodes = nodes;
         if (bitmap->mddev->bitmap_info.space == 0 ||
             bitmap->mddev->bitmap_info.space > sectors_reserved)
                 bitmap->mddev->bitmap_info.space = sectors_reserved;
@@ -2186,6 +2190,8 @@ __ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
 
 static ssize_t metadata_show(struct mddev *mddev, char *page)
 {
+        if (mddev_is_clustered(mddev))
+                return sprintf(page, "clustered\n");
         return sprintf(page, "%s\n", (mddev->bitmap_info.external
                                       ? "external" : "internal"));
 }
@@ -2198,7 +2204,8 @@ static ssize_t metadata_store(struct mddev *mddev, const char *buf, size_t len)
                 return -EBUSY;
         if (strncmp(buf, "external", 8) == 0)
                 mddev->bitmap_info.external = 1;
-        else if (strncmp(buf, "internal", 8) == 0)
+        else if ((strncmp(buf, "internal", 8) == 0) ||
+                        (strncmp(buf, "clustered", 9) == 0))
                 mddev->bitmap_info.external = 0;
         else
                 return -EINVAL;
diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index e2235600a72b..d141d4812c8c 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -22,8 +22,16 @@ struct dlm_lock_resource {
         struct dlm_lksb lksb;
         char *name; /* lock name. */
         uint32_t flags; /* flags to pass to dlm_lock() */
-        void (*bast)(void *arg, int mode); /* blocking AST function pointer*/
         struct completion completion; /* completion for synchronized locking */
+        void (*bast)(void *arg, int mode); /* blocking AST function pointer*/
+        struct mddev *mddev; /* pointing back to mddev. */
+};
+
+struct md_cluster_info {
+        /* dlm lock space and resources for clustered raid. */
+        dlm_lockspace_t *lockspace;
+        struct dlm_lock_resource *sb_lock;
+        struct mutex sb_mutex;
 };
 
 static void sync_ast(void *arg)
@@ -53,16 +61,18 @@ static int dlm_unlock_sync(struct dlm_lock_resource *res)
         return dlm_lock_sync(res, DLM_LOCK_NL);
 }
 
-static struct dlm_lock_resource *lockres_init(dlm_lockspace_t *lockspace,
+static struct dlm_lock_resource *lockres_init(struct mddev *mddev,
                 char *name, void (*bastfn)(void *arg, int mode), int with_lvb)
 {
         struct dlm_lock_resource *res = NULL;
         int ret, namelen;
+        struct md_cluster_info *cinfo = mddev->cluster_info;
 
         res = kzalloc(sizeof(struct dlm_lock_resource), GFP_KERNEL);
         if (!res)
                 return NULL;
-        res->ls = lockspace;
+        res->ls = cinfo->lockspace;
+        res->mddev = mddev;
         namelen = strlen(name);
         res->name = kzalloc(namelen + 1, GFP_KERNEL);
         if (!res->name) {
@@ -114,13 +124,62 @@ static void lockres_free(struct dlm_lock_resource *res)
         kfree(res);
 }
 
+static char *pretty_uuid(char *dest, char *src)
+{
+        int i, len = 0;
+
+        for (i = 0; i < 16; i++) {
+                if (i == 4 || i == 6 || i == 8 || i == 10)
+                        len += sprintf(dest + len, "-");
+                len += sprintf(dest + len, "%02x", (__u8)src[i]);
+        }
+        return dest;
+}
+
 static int join(struct mddev *mddev, int nodes)
 {
+        struct md_cluster_info *cinfo;
+        int ret;
+        char str[64];
+
+        if (!try_module_get(THIS_MODULE))
+                return -ENOENT;
+
+        cinfo = kzalloc(sizeof(struct md_cluster_info), GFP_KERNEL);
+        if (!cinfo)
+                return -ENOMEM;
+
+        memset(str, 0, 64);
+        pretty_uuid(str, mddev->uuid);
+        ret = dlm_new_lockspace(str, NULL, DLM_LSFL_FS, LVB_SIZE,
+                                NULL, NULL, NULL, &cinfo->lockspace);
+        if (ret)
+                goto err;
+        cinfo->sb_lock = lockres_init(mddev, "cmd-super",
+                                        NULL, 0);
+        if (!cinfo->sb_lock) {
+                ret = -ENOMEM;
+                goto err;
+        }
+        mutex_init(&cinfo->sb_mutex);
+        mddev->cluster_info = cinfo;
         return 0;
+err:
+        if (cinfo->lockspace)
+                dlm_release_lockspace(cinfo->lockspace, 2);
+        kfree(cinfo);
+        module_put(THIS_MODULE);
+        return ret;
 }
 
 static int leave(struct mddev *mddev)
 {
+        struct md_cluster_info *cinfo = mddev->cluster_info;
+
+        if (!cinfo)
+                return 0;
+        lockres_free(cinfo->sb_lock);
+        dlm_release_lockspace(cinfo->lockspace, 2);
         return 0;
 }
 
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 57ecb51ec5fd..3387f940140b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7279,6 +7279,8 @@ int md_setup_cluster(struct mddev *mddev, int nodes)
 
 void md_cluster_stop(struct mddev *mddev)
 {
+        if (!md_cluster_ops)
+                return;
         md_cluster_ops->leave(mddev);
         module_put(md_cluster_mod);
 }
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 018593197c4d..80fc89976915 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -203,6 +203,8 @@ extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
                                 int is_new);
 extern void md_ack_all_badblocks(struct badblocks *bb);
 
+struct md_cluster_info;
+
 struct mddev {
         void                            *private;
         struct md_personality           *pers;
@@ -431,6 +433,7 @@ struct mddev {
                 unsigned long           daemon_sleep; /* how many jiffies between updates? */
                 unsigned long           max_write_behind; /* write-behind mode */
                 int                     external;
+                int                     nodes; /* Maximum number of nodes in the cluster */
         } bitmap_info;
 
         atomic_t                        max_corr_read_errors; /* max read retries */
@@ -449,6 +452,7 @@ struct mddev {
         struct work_struct flush_work;
         struct work_struct event_work;  /* used by dm to report failure event */
         void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
+        struct md_cluster_info          *cluster_info;
 };
 
 static inline int __must_check mddev_lock(struct mddev *mddev)
@@ -676,4 +680,8 @@ static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 }
 
 extern struct md_cluster_operations *md_cluster_ops;
+static inline int mddev_is_clustered(struct mddev *mddev)
+{
+        return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
+}
 #endif /* _MD_MD_H */