[PATCH] md: really get sb_size setting right in all cases
[pandora-kernel.git] / drivers / md / md.c
index 6580e0f..1554b92 100644 (file)
@@ -34,6 +34,7 @@
 
 #include <linux/module.h>
 #include <linux/config.h>
+#include <linux/kthread.h>
 #include <linux/linkage.h>
 #include <linux/raid/md.h>
 #include <linux/raid/bitmap.h>
@@ -256,8 +257,7 @@ static inline void mddev_unlock(mddev_t * mddev)
 {
        up(&mddev->reconfig_sem);
 
-       if (mddev->thread)
-               md_wakeup_thread(mddev->thread);
+       md_wakeup_thread(mddev->thread);
 }
 
 mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
@@ -394,7 +394,7 @@ int sync_page_io(struct block_device *bdev, sector_t sector, int size,
        return ret;
 }
 
-static int read_disk_sb(mdk_rdev_t * rdev)
+static int read_disk_sb(mdk_rdev_t * rdev, int size)
 {
        char b[BDEVNAME_SIZE];
        if (!rdev->sb_page) {
@@ -405,7 +405,7 @@ static int read_disk_sb(mdk_rdev_t * rdev)
                return 0;
 
 
-       if (!sync_page_io(rdev->bdev, rdev->sb_offset<<1, MD_SB_BYTES, rdev->sb_page, READ))
+       if (!sync_page_io(rdev->bdev, rdev->sb_offset<<1, size, rdev->sb_page, READ))
                goto fail;
        rdev->sb_loaded = 1;
        return 0;
@@ -532,7 +532,7 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version
        sb_offset = calc_dev_sboffset(rdev->bdev);
        rdev->sb_offset = sb_offset;
 
-       ret = read_disk_sb(rdev);
+       ret = read_disk_sb(rdev, MD_SB_BYTES);
        if (ret) return ret;
 
        ret = -EINVAL;
@@ -565,6 +565,7 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version
 
        rdev->preferred_minor = sb->md_minor;
        rdev->data_offset = 0;
+       rdev->sb_size = MD_SB_BYTES;
 
        if (sb->level == LEVEL_MULTIPATH)
                rdev->desc_nr = -1;
@@ -623,6 +624,8 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                mddev->raid_disks = sb->raid_disks;
                mddev->size = sb->size;
                mddev->events = md_event(sb);
+               mddev->bitmap_offset = 0;
+               mddev->default_bitmap_offset = MD_SB_BYTES >> 9;
 
                if (sb->state & (1<<MD_SB_CLEAN))
                        mddev->recovery_cp = MaxSector;
@@ -643,12 +646,12 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 
                if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
                    mddev->bitmap_file == NULL) {
-                       if (mddev->level != 1) {
+                       if (mddev->level != 1 && mddev->level != 5 && mddev->level != 6) {
                                /* FIXME use a better test */
                                printk(KERN_WARNING "md: bitmaps only support for raid1\n");
                                return -EINVAL;
                        }
-                       mddev->bitmap_offset = (MD_SB_BYTES >> 9);
+                       mddev->bitmap_offset = mddev->default_bitmap_offset;
                }
 
        } else if (mddev->pers == NULL) {
@@ -669,6 +672,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 
        if (mddev->level != LEVEL_MULTIPATH) {
                rdev->faulty = 0;
+               rdev->flags = 0;
                desc = sb->disks + rdev->desc_nr;
 
                if (desc->state & (1<<MD_DISK_FAULTY))
@@ -678,6 +682,8 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                        rdev->in_sync = 1;
                        rdev->raid_disk = desc->raid_disk;
                }
+               if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
+                       set_bit(WriteMostly, &rdev->flags);
        } else /* MULTIPATH are always insync */
                rdev->in_sync = 1;
        return 0;
@@ -706,6 +712,8 @@ 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;
 
+       rdev->sb_size = MD_SB_BYTES;
+
        sb = (mdp_super_t*)page_address(rdev->sb_page);
 
        memset(sb, 0, sizeof(*sb));
@@ -776,6 +784,8 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
                        spare++;
                        working++;
                }
+               if (test_bit(WriteMostly, &rdev2->flags))
+                       d->state |= (1<<MD_DISK_WRITEMOSTLY);
        }
        
        /* now set the "removed" and "faulty" bits on any missing devices */
@@ -831,6 +841,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
        int ret;
        sector_t sb_offset;
        char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
+       int bmask;
 
        /*
         * Calculate the position of the superblock.
@@ -859,7 +870,10 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
        }
        rdev->sb_offset = sb_offset;
 
-       ret = read_disk_sb(rdev);
+       /* superblock is rarely larger than 1K, but it can be larger,
+        * and it is safe to read 4k, so we do that
+        */
+       ret = read_disk_sb(rdev, 4096);
        if (ret) return ret;
 
 
@@ -869,7 +883,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
            sb->major_version != cpu_to_le32(1) ||
            le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
            le64_to_cpu(sb->super_offset) != (rdev->sb_offset<<1) ||
-           sb->feature_map != 0)
+           (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
                return -EINVAL;
 
        if (calc_sb_1_csum(sb) != sb->sb_csum) {
@@ -885,6 +899,11 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
        rdev->preferred_minor = 0xffff;
        rdev->data_offset = le64_to_cpu(sb->data_offset);
 
+       rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
+       bmask = queue_hardsect_size(rdev->bdev->bd_disk->queue)-1;
+       if (rdev->sb_size & bmask)
+               rdev-> sb_size = (rdev->sb_size | bmask)+1;
+
        if (refdev == 0)
                return 1;
        else {
@@ -938,13 +957,16 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                mddev->raid_disks = le32_to_cpu(sb->raid_disks);
                mddev->size = le64_to_cpu(sb->size)/2;
                mddev->events = le64_to_cpu(sb->events);
+               mddev->bitmap_offset = 0;
+               mddev->default_bitmap_offset = 0;
+               mddev->default_bitmap_offset = 1024;
                
                mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
                memcpy(mddev->uuid, sb->set_uuid, 16);
 
                mddev->max_disks =  (4096-256)/2;
 
-               if ((le32_to_cpu(sb->feature_map) & 1) &&
+               if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
                    mddev->bitmap_file == NULL ) {
                        if (mddev->level != 1) {
                                printk(KERN_WARNING "md: bitmaps only supported for raid1\n");
@@ -985,6 +1007,9 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                        rdev->raid_disk = role;
                        break;
                }
+               rdev->flags = 0;
+               if (sb->devflags & WriteMostly1)
+                       set_bit(WriteMostly, &rdev->flags);
        } else /* MULTIPATH are always insync */
                rdev->in_sync = 1;
 
@@ -1016,7 +1041,7 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
 
        if (mddev->bitmap && mddev->bitmap_file == NULL) {
                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_offset);
-               sb->feature_map = cpu_to_le32(1);
+               sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
        }
 
        max_dev = 0;
@@ -1362,7 +1387,7 @@ repeat:
                dprintk("%s ", bdevname(rdev->bdev,b));
                if (!rdev->faulty) {
                        md_super_write(mddev,rdev,
-                                      rdev->sb_offset<<1, MD_SB_BYTES,
+                                      rdev->sb_offset<<1, rdev->sb_size,
                                       rdev->sb_page);
                        dprintk(KERN_INFO "(write) %s's sb offset: %llu\n",
                                bdevname(rdev->bdev,b),
@@ -1688,6 +1713,7 @@ static int do_md_run(mddev_t * mddev)
        mddev->pers = pers[pnum];
        spin_unlock(&pers_lock);
 
+       mddev->recovery = 0;
        mddev->resync_max_sectors = mddev->size << 1; /* may be over-ridden by personality */
 
        /* before we start the array running, initialise the bitmap */
@@ -1712,6 +1738,7 @@ static int do_md_run(mddev_t * mddev)
        mddev->in_sync = 1;
        
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+       md_wakeup_thread(mddev->thread);
        
        if (mddev->sb_dirty)
                md_update_sb(mddev);
@@ -1798,6 +1825,8 @@ static int do_md_stop(mddev_t * mddev, int ro)
                                goto out;
                        mddev->ro = 1;
                } else {
+                       bitmap_flush(mddev);
+                       wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
                        if (mddev->ro)
                                set_disk_ro(disk, 0);
                        blk_queue_make_request(mddev->queue, md_fail_request);
@@ -1822,6 +1851,7 @@ static int do_md_stop(mddev_t * mddev, int ro)
                fput(mddev->bitmap_file);
                mddev->bitmap_file = NULL;
        }
+       mddev->bitmap_offset = 0;
 
        /*
         * Free resources if final stop
@@ -2067,6 +2097,8 @@ static int get_array_info(mddev_t * mddev, void __user * arg)
        info.state         = 0;
        if (mddev->in_sync)
                info.state = (1<<MD_SB_CLEAN);
+       if (mddev->bitmap && mddev->bitmap_offset)
+               info.state = (1<<MD_SB_BITMAP_PRESENT);
        info.active_disks  = active;
        info.working_disks = working;
        info.failed_disks  = failed;
@@ -2081,7 +2113,7 @@ static int get_array_info(mddev_t * mddev, void __user * arg)
        return 0;
 }
 
-static int get_bitmap_file(mddev_t * mddev, void * arg)
+static int get_bitmap_file(mddev_t * mddev, void __user * arg)
 {
        mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
        char *ptr, *buf = NULL;
@@ -2140,6 +2172,8 @@ static int get_disk_info(mddev_t * mddev, void __user * arg)
                        info.state |= (1<<MD_DISK_ACTIVE);
                        info.state |= (1<<MD_DISK_SYNC);
                }
+               if (test_bit(WriteMostly, &rdev->flags))
+                       info.state |= (1<<MD_DISK_WRITEMOSTLY);
        } else {
                info.major = info.minor = 0;
                info.raid_disk = -1;
@@ -2204,8 +2238,11 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
                               mdname(mddev));
                        return -EINVAL;
                }
-               rdev = md_import_device(dev, mddev->major_version,
-                                       mddev->minor_version);
+               if (mddev->persistent)
+                       rdev = md_import_device(dev, mddev->major_version,
+                                               mddev->minor_version);
+               else
+                       rdev = md_import_device(dev, -1, -1);
                if (IS_ERR(rdev)) {
                        printk(KERN_WARNING 
                                "md: md_import_device returned %ld\n",
@@ -2225,14 +2262,16 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
                rdev->saved_raid_disk = rdev->raid_disk;
 
                rdev->in_sync = 0; /* just to be sure */
+               if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+                       set_bit(WriteMostly, &rdev->flags);
+
                rdev->raid_disk = -1;
                err = bind_rdev_to_array(rdev, mddev);
                if (err)
                        export_rdev(rdev);
 
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-               if (mddev->thread)
-                       md_wakeup_thread(mddev->thread);
+               md_wakeup_thread(mddev->thread);
                return err;
        }
 
@@ -2266,6 +2305,9 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
                else
                        rdev->in_sync = 0;
 
+               if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+                       set_bit(WriteMostly, &rdev->flags);
+
                err = bind_rdev_to_array(rdev, mddev);
                if (err) {
                        export_rdev(rdev);
@@ -2425,25 +2467,51 @@ static int set_bitmap_file(mddev_t *mddev, int fd)
 {
        int err;
 
-       if (mddev->pers)
-               return -EBUSY;
+       if (mddev->pers) {
+               if (!mddev->pers->quiesce)
+                       return -EBUSY;
+               if (mddev->recovery || mddev->sync_thread)
+                       return -EBUSY;
+               /* we should be able to change the bitmap.. */
+       }
 
-       mddev->bitmap_file = fget(fd);
 
-       if (mddev->bitmap_file == NULL) {
-               printk(KERN_ERR "%s: error: failed to get bitmap file\n",
-                       mdname(mddev));
-               return -EBADF;
-       }
+       if (fd >= 0) {
+               if (mddev->bitmap)
+                       return -EEXIST; /* cannot add when bitmap is present */
+               mddev->bitmap_file = fget(fd);
 
-       err = deny_bitmap_write_access(mddev->bitmap_file);
-       if (err) {
-               printk(KERN_ERR "%s: error: bitmap file is already in use\n",
-                       mdname(mddev));
-               fput(mddev->bitmap_file);
-               mddev->bitmap_file = NULL;
-       } else
+               if (mddev->bitmap_file == NULL) {
+                       printk(KERN_ERR "%s: error: failed to get bitmap file\n",
+                              mdname(mddev));
+                       return -EBADF;
+               }
+
+               err = deny_bitmap_write_access(mddev->bitmap_file);
+               if (err) {
+                       printk(KERN_ERR "%s: error: bitmap file is already in use\n",
+                              mdname(mddev));
+                       fput(mddev->bitmap_file);
+                       mddev->bitmap_file = NULL;
+                       return err;
+               }
                mddev->bitmap_offset = 0; /* file overrides offset */
+       } else if (mddev->bitmap == NULL)
+               return -ENOENT; /* cannot remove what isn't there */
+       err = 0;
+       if (mddev->pers) {
+               mddev->pers->quiesce(mddev, 1);
+               if (fd >= 0)
+                       err = bitmap_create(mddev);
+               if (fd < 0 || err)
+                       bitmap_destroy(mddev);
+               mddev->pers->quiesce(mddev, 0);
+       } else if (fd < 0) {
+               if (mddev->bitmap_file)
+                       fput(mddev->bitmap_file);
+               mddev->bitmap_file = NULL;
+       }
+
        return err;
 }
 
@@ -2523,6 +2591,11 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
 {
        int rv = 0;
        int cnt = 0;
+       int state = 0;
+
+       /* calculate expected state,ignoring low bits */
+       if (mddev->bitmap && mddev->bitmap_offset)
+               state |= (1 << MD_SB_BITMAP_PRESENT);
 
        if (mddev->major_version != info->major_version ||
            mddev->minor_version != info->minor_version ||
@@ -2531,12 +2604,16 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
            mddev->level         != info->level         ||
 /*         mddev->layout        != info->layout        || */
            !mddev->persistent   != info->not_persistent||
-           mddev->chunk_size    != info->chunk_size    )
+           mddev->chunk_size    != info->chunk_size    ||
+           /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
+           ((state^info->state) & 0xfffffe00)
+               )
                return -EINVAL;
        /* Check there is only one change */
        if (mddev->size != info->size) cnt++;
        if (mddev->raid_disks != info->raid_disks) cnt++;
        if (mddev->layout != info->layout) cnt++;
+       if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) cnt++;
        if (cnt == 0) return 0;
        if (cnt > 1) return -EINVAL;
 
@@ -2615,6 +2692,35 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
                        }
                }
        }
+       if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
+               if (mddev->pers->quiesce == NULL)
+                       return -EINVAL;
+               if (mddev->recovery || mddev->sync_thread)
+                       return -EBUSY;
+               if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
+                       /* add the bitmap */
+                       if (mddev->bitmap)
+                               return -EEXIST;
+                       if (mddev->default_bitmap_offset == 0)
+                               return -EINVAL;
+                       mddev->bitmap_offset = mddev->default_bitmap_offset;
+                       mddev->pers->quiesce(mddev, 1);
+                       rv = bitmap_create(mddev);
+                       if (rv)
+                               bitmap_destroy(mddev);
+                       mddev->pers->quiesce(mddev, 0);
+               } else {
+                       /* remove the bitmap */
+                       if (!mddev->bitmap)
+                               return -ENOENT;
+                       if (mddev->bitmap->file)
+                               return -EINVAL;
+                       mddev->pers->quiesce(mddev, 1);
+                       bitmap_destroy(mddev);
+                       mddev->pers->quiesce(mddev, 0);
+                       mddev->bitmap_offset = 0;
+               }
+       }
        md_update_sb(mddev);
        return rv;
 }
@@ -2776,7 +2882,7 @@ static int md_ioctl(struct inode *inode, struct file *file,
                        goto done_unlock;
 
                case GET_BITMAP_FILE:
-                       err = get_bitmap_file(mddev, (void *)arg);
+                       err = get_bitmap_file(mddev, argp);
                        goto done_unlock;
 
                case GET_DISK_INFO:
@@ -2945,18 +3051,6 @@ static int md_thread(void * arg)
 {
        mdk_thread_t *thread = arg;
 
-       lock_kernel();
-
-       /*
-        * Detach thread
-        */
-
-       daemonize(thread->name, mdname(thread->mddev));
-
-       current->exit_signal = SIGCHLD;
-       allow_signal(SIGKILL);
-       thread->tsk = current;
-
        /*
         * md_thread is a 'system-thread', it's priority should be very
         * high. We avoid resource deadlocks individually in each
@@ -2968,14 +3062,14 @@ static int md_thread(void * arg)
         * bdflush, otherwise bdflush will deadlock if there are too
         * many dirty RAID5 blocks.
         */
-       unlock_kernel();
 
        complete(thread->event);
-       while (thread->run) {
+       while (!kthread_should_stop()) {
                void (*run)(mddev_t *);
 
                wait_event_interruptible_timeout(thread->wqueue,
-                                                test_bit(THREAD_WAKEUP, &thread->flags),
+                                                test_bit(THREAD_WAKEUP, &thread->flags)
+                                                || kthread_should_stop(),
                                                 thread->timeout);
                try_to_freeze();
 
@@ -2984,11 +3078,8 @@ static int md_thread(void * arg)
                run = thread->run;
                if (run)
                        run(thread->mddev);
-
-               if (signal_pending(current))
-                       flush_signals(current);
        }
-       complete(thread->event);
+
        return 0;
 }
 
@@ -3005,11 +3096,9 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
                                 const char *name)
 {
        mdk_thread_t *thread;
-       int ret;
        struct completion event;
 
-       thread = (mdk_thread_t *) kmalloc
-                               (sizeof(mdk_thread_t), GFP_KERNEL);
+       thread = kmalloc(sizeof(mdk_thread_t), GFP_KERNEL);
        if (!thread)
                return NULL;
 
@@ -3022,8 +3111,8 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
        thread->mddev = mddev;
        thread->name = name;
        thread->timeout = MAX_SCHEDULE_TIMEOUT;
-       ret = kernel_thread(md_thread, thread, 0);
-       if (ret < 0) {
+       thread->tsk = kthread_run(md_thread, thread, mdname(thread->mddev));
+       if (IS_ERR(thread->tsk)) {
                kfree(thread);
                return NULL;
        }
@@ -3033,21 +3122,9 @@ mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
 
 void md_unregister_thread(mdk_thread_t *thread)
 {
-       struct completion event;
-
-       init_completion(&event);
-
-       thread->event = &event;
-
-       /* As soon as ->run is set to NULL, the task could disappear,
-        * so we need to hold tasklist_lock until we have sent the signal
-        */
        dprintk("interrupting MD-thread pid %d\n", thread->tsk->pid);
-       read_lock(&tasklist_lock);
-       thread->run = NULL;
-       send_sig(SIGKILL, thread->tsk, 1);
-       read_unlock(&tasklist_lock);
-       wait_for_completion(&event);
+
+       kthread_stop(thread->tsk);
        kfree(thread);
 }
 
@@ -3254,10 +3331,13 @@ static int md_seq_show(struct seq_file *seq, void *v)
                        char b[BDEVNAME_SIZE];
                        seq_printf(seq, " %s[%d]",
                                bdevname(rdev->bdev,b), rdev->desc_nr);
+                       if (test_bit(WriteMostly, &rdev->flags))
+                               seq_printf(seq, "(W)");
                        if (rdev->faulty) {
                                seq_printf(seq, "(F)");
                                continue;
-                       }
+                       } else if (rdev->raid_disk < 0)
+                               seq_printf(seq, "(S)"); /* spare */
                        size += rdev->size;
                }
 
@@ -3269,6 +3349,15 @@ static int md_seq_show(struct seq_file *seq, void *v)
                                seq_printf(seq, "\n      %llu blocks",
                                        (unsigned long long)size);
                }
+               if (mddev->persistent) {
+                       if (mddev->major_version != 0 ||
+                           mddev->minor_version != 90) {
+                               seq_printf(seq," super %d.%d",
+                                          mddev->major_version,
+                                          mddev->minor_version);
+                       }
+               } else
+                       seq_printf(seq, " super non-persistent");
 
                if (mddev->pers) {
                        mddev->pers->status (seq, mddev);
@@ -3411,7 +3500,6 @@ void md_done_sync(mddev_t *mddev, int blocks, int ok)
  */
 void md_write_start(mddev_t *mddev, struct bio *bi)
 {
-       DEFINE_WAIT(w);
        if (bio_data_dir(bi) != WRITE)
                return;
 
@@ -3484,7 +3572,6 @@ static void md_do_sync(mddev_t *mddev)
                        goto skip;
                }
                ITERATE_MDDEV(mddev2,tmp) {
-                       printk(".");
                        if (mddev2 == mddev)
                                continue;
                        if (mddev2->curr_resync && 
@@ -4007,3 +4094,5 @@ EXPORT_SYMBOL(md_wakeup_thread);
 EXPORT_SYMBOL(md_print_devices);
 EXPORT_SYMBOL(md_check_recovery);
 MODULE_LICENSE("GPL");
+MODULE_ALIAS("md");
+MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);