[PATCH] md: extend md sysfs support to component devices.

Each device in an md array how has a corresponding
  /sys/block/mdX/md/devNN/
directory which can contain attributes.  Currently there is only 'state' which
summarises the state, nd 'super' which has a copy of the superblock, and
'block' which is a symlink to the block device.

Also, /sys/block/mdX/md/rdNN represents slot 'NN' in the array, and is a
symlink to the relevant 'devNN'.  Obviously spare devices do not have a slot
in the array, and so don't have such a symlink.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 162 insertions, 8 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index a68ad8547325..74520b50c307 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -711,6 +711,7 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
          */
         int i;
         int active=0, working=0,failed=0,spare=0,nr_disks=0;
+        unsigned int fixdesc=0;
 
         rdev->sb_size = MD_SB_BYTES;
 
@@ -758,16 +759,28 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         sb->disks[0].state = (1<<MD_DISK_REMOVED);
         ITERATE_RDEV(mddev,rdev2,tmp) {
                 mdp_disk_t *d;
+                int desc_nr;
                 if (rdev2->raid_disk >= 0 && rdev2->in_sync && !rdev2->faulty)
-                        rdev2->desc_nr = rdev2->raid_disk;
+                        desc_nr = rdev2->raid_disk;
                 else
-                        rdev2->desc_nr = next_spare++;
+                        desc_nr = next_spare++;
+                if (desc_nr != rdev2->desc_nr) {
+                        fixdesc |= (1 << desc_nr);
+                        rdev2->desc_nr = desc_nr;
+                        if (rdev2->raid_disk >= 0) {
+                                char nm[20];
+                                sprintf(nm, "rd%d", rdev2->raid_disk);
+                                sysfs_remove_link(&mddev->kobj, nm);
+                        }
+                        sysfs_remove_link(&rdev2->kobj, "block");
+                        kobject_del(&rdev2->kobj);
+                }
                 d = &sb->disks[rdev2->desc_nr];
                 nr_disks++;
                 d->number = rdev2->desc_nr;
                 d->major = MAJOR(rdev2->bdev->bd_dev);
                 d->minor = MINOR(rdev2->bdev->bd_dev);
-                if (rdev2->raid_disk >= 0 && rdev->in_sync && !rdev2->faulty)
+                if (rdev2->raid_disk >= 0 && rdev2->in_sync && !rdev2->faulty)
                         d->raid_disk = rdev2->raid_disk;
                 else
                         d->raid_disk = rdev2->desc_nr; /* compatibility */
@@ -787,7 +800,22 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
                 if (test_bit(WriteMostly, &rdev2->flags))
                         d->state |= (1<<MD_DISK_WRITEMOSTLY);
         }
-        
+        if (fixdesc)
+                ITERATE_RDEV(mddev,rdev2,tmp)
+                        if (fixdesc & (1<<rdev2->desc_nr)) {
+                                snprintf(rdev2->kobj.name, KOBJ_NAME_LEN, "dev%d",
+                                         rdev2->desc_nr);
+                                kobject_add(&rdev2->kobj);
+                                sysfs_create_link(&rdev2->kobj,
+                                                  &rdev2->bdev->bd_disk->kobj,
+                                                  "block");
+                                if (rdev2->raid_disk >= 0) {
+                                        char nm[20];
+                                        sprintf(nm, "rd%d", rdev2->raid_disk);
+                                        sysfs_create_link(&mddev->kobj,
+                                                          &rdev2->kobj, nm);
+                                }
+                        }
         /* now set the "removed" and "faulty" bits on any missing devices */
         for (i=0 ; i < mddev->raid_disks ; i++) {
                 mdp_disk_t *d = &sb->disks[i];
@@ -1147,6 +1175,13 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
         list_add(&rdev->same_set, &mddev->disks);
         rdev->mddev = mddev;
         printk(KERN_INFO "md: bind<%s>\n", bdevname(rdev->bdev,b));
+
+        rdev->kobj.k_name = NULL;
+        snprintf(rdev->kobj.name, KOBJ_NAME_LEN, "dev%d", rdev->desc_nr);
+        rdev->kobj.parent = kobject_get(&mddev->kobj);
+        kobject_add(&rdev->kobj);
+
+        sysfs_create_link(&rdev->kobj, &rdev->bdev->bd_disk->kobj, "block");
         return 0;
 }
 
@@ -1160,6 +1195,8 @@ static void unbind_rdev_from_array(mdk_rdev_t * rdev)
         list_del_init(&rdev->same_set);
         printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
         rdev->mddev = NULL;
+        sysfs_remove_link(&rdev->kobj, "block");
+        kobject_del(&rdev->kobj);
 }
 
 /*
@@ -1215,7 +1252,7 @@ static void export_rdev(mdk_rdev_t * rdev)
         md_autodetect_dev(rdev->bdev->bd_dev);
 #endif
         unlock_rdev(rdev);
-        kfree(rdev);
+        kobject_put(&rdev->kobj);
 }
 
 static void kick_rdev_from_array(mdk_rdev_t * rdev)
@@ -1414,6 +1451,94 @@ repeat:
 
 }
 
+struct rdev_sysfs_entry {
+        struct attribute attr;
+        ssize_t (*show)(mdk_rdev_t *, char *);
+        ssize_t (*store)(mdk_rdev_t *, const char *, size_t);
+};
+
+static ssize_t
+rdev_show_state(mdk_rdev_t *rdev, char *page)
+{
+        char *sep = "";
+        int len=0;
+
+        if (rdev->faulty) {
+                len+= sprintf(page+len, "%sfaulty",sep);
+                sep = ",";
+        }
+        if (rdev->in_sync) {
+                len += sprintf(page+len, "%sin_sync",sep);
+                sep = ",";
+        }
+        if (!rdev->faulty && !rdev->in_sync) {
+                len += sprintf(page+len, "%sspare", sep);
+                sep = ",";
+        }
+        return len+sprintf(page+len, "\n");
+}
+
+static struct rdev_sysfs_entry rdev_state = {
+        .attr = {.name = "state", .mode = S_IRUGO },
+        .show = rdev_show_state,
+};
+
+static ssize_t
+rdev_show_super(mdk_rdev_t *rdev, char *page)
+{
+        if (rdev->sb_loaded && rdev->sb_size) {
+                memcpy(page, page_address(rdev->sb_page), rdev->sb_size);
+                return rdev->sb_size;
+        } else
+                return 0;
+}
+static struct rdev_sysfs_entry rdev_super = {
+        .attr = {.name = "super", .mode = S_IRUGO },
+        .show = rdev_show_super,
+};
+static struct attribute *rdev_default_attrs[] = {
+        &rdev_state.attr,
+        &rdev_super.attr,
+        NULL,
+};
+static ssize_t
+rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+        struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
+        mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);
+
+        if (!entry->show)
+                return -EIO;
+        return entry->show(rdev, page);
+}
+
+static ssize_t
+rdev_attr_store(struct kobject *kobj, struct attribute *attr,
+              const char *page, size_t length)
+{
+        struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
+        mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);
+
+        if (!entry->store)
+                return -EIO;
+        return entry->store(rdev, page, length);
+}
+
+static void rdev_free(struct kobject *ko)
+{
+        mdk_rdev_t *rdev = container_of(ko, mdk_rdev_t, kobj);
+        kfree(rdev);