[PATCH] md: all hot-add and hot-remove of md intent logging bitmaps

Both file-bitmaps and superblock bitmaps are supported.

If you add a bitmap file on the array device, you lose.

This introduces a 'default_bitmap_offset' field in mddev, as the ioctl used
for adding a superblock bitmap doesn't have room for giving an offset.  Later,
this value will be setable via sysfs.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 127 insertions, 17 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 63c566165189..ae654466dc23 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -623,6 +623,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                 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;
@@ -648,7 +649,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                                 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) {
@@ -939,6 +940,9 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                 mddev->size = le64_to_cpu(sb->size)/2;
                 mddev->events = le64_to_cpu(sb->events);
                 mddev->bitmap_offset = 0;
+                mddev->default_bitmap_offset = 0;
+                if (mddev->minor_version == 0)
+                        mddev->default_bitmap_offset = -(64*1024)/512;
                 
                 mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
                 memcpy(mddev->uuid, sb->set_uuid, 16);
@@ -2073,6 +2077,8 @@ 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;
@@ -2430,25 +2436,51 @@ static int set_bitmap_file(mddev_t *mddev, int fd)
 {
         int err;
 
-        if (mddev->pers || mddev->bitmap_file)
-                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;
 }
 
@@ -2528,6 +2560,11 @@ 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 ||
@@ -2536,12 +2573,16 @@ 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;
 
@@ -2620,6 +2661,35 @@ 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;
 }
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ace41c571aeb..ba643e4bfac9 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1565,6 +1565,35 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
         return 0;
 }
 
+void raid1_quiesce(mddev_t *mddev, int state)
+{
+        conf_t *conf = mddev_to_conf(mddev);
+
+        switch(state) {
+        case 0:
+                spin_lock_irq(&conf->resync_lock);
+                conf->barrier++;
+                wait_event_lock_irq(conf->wait_idle, !conf->nr_pending,
+                                    conf->resync_lock, raid1_unplug(mddev->queue));
+                spin_unlock_irq(&conf->resync_lock);
+                break;
+        case 1:
+                spin_lock_irq(&conf->resync_lock);
+                conf->barrier--;
+                spin_unlock_irq(&conf->resync_lock);
+                wake_up(&conf->wait_resume);
+                wake_up(&conf->wait_idle);
+                break;
+        }
+        if (mddev->thread) {
+                if (mddev->bitmap)
+                        mddev->thread->timeout = mddev->bitmap->daemon_sleep * HZ;
+                else
+                        mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
+                md_wakeup_thread(mddev->thread);
+        }
+}
+
 
 static mdk_personality_t raid1_personality =
 {
@@ -1581,6 +1610,7 @@ static mdk_personality_t raid1_personality =
         .sync_request   = sync_request,
         .resize         = raid1_resize,
         .reshape        = raid1_reshape,
+        .quiesce        = raid1_quiesce,
 };
 
 static int __init raid_init(void)
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 8c14ba565a45..817062bf7352 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -278,6 +278,10 @@ struct mddev_s
                                                         * start of bitmap. May be
                                                         * negative, but not '0'
                                                         */
+        long                            default_bitmap_offset; /* this is the offset to use when
+                                                                * hot-adding a bitmap.  It should
+                                                                * eventually be settable by sysfs.
+                                                                */
 
         struct list_head                all_mddevs;
 };
@@ -314,6 +318,12 @@ struct mdk_personality_s
         int (*resize) (mddev_t *mddev, sector_t sectors);
         int (*reshape) (mddev_t *mddev, int raid_disks);
         int (*reconfig) (mddev_t *mddev, int layout, int chunk_size);
+        /* quiesce moves between quiescence states
+         * 0 - fully active
+         * 1 - no new requests allowed
+         * others - reserved
+         */
+        void (*quiesce) (mddev_t *mddev, int state);
 };