[PATCH] md: write intent bitmap support for raid10

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 157 insertions, 21 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 50bd7b152f28..8f58a447d9f0 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -18,7 +18,9 @@
  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#include "dm-bio-list.h"
 #include <linux/raid/raid10.h>
+#include <linux/raid/bitmap.h>
 
 /*
  * RAID10 provides a combination of RAID0 and RAID1 functionality.
@@ -306,9 +308,11 @@ static int raid10_end_write_request(struct bio *bio, unsigned int bytes_done, in
         /*
          * this branch is our 'one mirror IO has finished' event handler:
          */
-        if (!uptodate)
+        if (!uptodate) {
                 md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
-        else
+                /* an I/O failed, we can't clear the bitmap */
+                set_bit(R10BIO_Degraded, &r10_bio->state);
+        } else
                 /*
                  * Set R10BIO_Uptodate in our master bio, so that
                  * we will return a good error code for to the higher
@@ -328,6 +332,11 @@ static int raid10_end_write_request(struct bio *bio, unsigned int bytes_done, in
          * already.
          */
         if (atomic_dec_and_test(&r10_bio->remaining)) {
+                /* clear the bitmap if all writes complete successfully */
+                bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
+                                r10_bio->sectors,
+                                !test_bit(R10BIO_Degraded, &r10_bio->state),
+                                0);
                 md_write_end(r10_bio->mddev);
                 raid_end_bio_io(r10_bio);
         }
@@ -486,8 +495,9 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio)
         rcu_read_lock();
         /*
          * Check if we can balance. We can balance on the whole
-         * device if no resync is going on, or below the resync window.
-         * We take the first readable disk when above the resync window.
+         * device if no resync is going on (recovery is ok), or below
+         * the resync window. We take the first readable disk when
+         * above the resync window.
          */
         if (conf->mddev->recovery_cp < MaxSector
             && (this_sector + sectors >= conf->next_resync)) {
@@ -591,7 +601,10 @@ static void unplug_slaves(mddev_t *mddev)
 
 static void raid10_unplug(request_queue_t *q)
 {
+        mddev_t *mddev = q->queuedata;
+
         unplug_slaves(q->queuedata);
+        md_wakeup_thread(mddev->thread);
 }
 
 static int raid10_issue_flush(request_queue_t *q, struct gendisk *disk,
@@ -647,12 +660,13 @@ static int raid10_issue_flush(request_queue_t *q, struct gendisk *disk,
  */
 #define RESYNC_DEPTH 32
 
-static void raise_barrier(conf_t *conf)
+static void raise_barrier(conf_t *conf, int force)
 {
+        BUG_ON(force && !conf->barrier);
         spin_lock_irq(&conf->resync_lock);
 
-        /* Wait until no block IO is waiting */
-        wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting,
+        /* Wait until no block IO is waiting (unless 'force') */
+        wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
                             conf->resync_lock,
                             raid10_unplug(conf->mddev->queue));
 
@@ -710,6 +724,8 @@ static int make_request(request_queue_t *q, struct bio * bio)
         int i;
         int chunk_sects = conf->chunk_mask + 1;
         const int rw = bio_data_dir(bio);
+        struct bio_list bl;
+        unsigned long flags;
 
         if (unlikely(bio_barrier(bio))) {
                 bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
@@ -767,6 +783,7 @@ static int make_request(request_queue_t *q, struct bio * bio)
 
         r10_bio->mddev = mddev;
         r10_bio->sector = bio->bi_sector;
+        r10_bio->state = 0;
 
         if (rw == READ) {
                 /*
@@ -811,13 +828,16 @@ static int make_request(request_queue_t *q, struct bio * bio)
                     !test_bit(Faulty, &rdev->flags)) {
                         atomic_inc(&rdev->nr_pending);
                         r10_bio->devs[i].bio = bio;
-                } else
+                } else {
                         r10_bio->devs[i].bio = NULL;
+                        set_bit(R10BIO_Degraded, &r10_bio->state);
+                }
         }
         rcu_read_unlock();
 
-        atomic_set(&r10_bio->remaining, 1);
+        atomic_set(&r10_bio->remaining, 0);
 
+        bio_list_init(&bl);
         for (i = 0; i < conf->copies; i++) {
                 struct bio *mbio;
                 int d = r10_bio->devs[i].devnum;
@@ -835,13 +855,14 @@ static int make_request(request_queue_t *q, struct bio * bio)
                 mbio->bi_private = r10_bio;
 
                 atomic_inc(&r10_bio->remaining);
-                generic_make_request(mbio);
+                bio_list_add(&bl, mbio);
         }
 
-        if (atomic_dec_and_test(&r10_bio->remaining)) {
-                md_write_end(mddev);
-                raid_end_bio_io(r10_bio);
-        }
+        bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
+        spin_lock_irqsave(&conf->device_lock, flags);
+        bio_list_merge(&conf->pending_bio_list, &bl);
+        blk_plug_device(mddev->queue);
+        spin_unlock_irqrestore(&conf->device_lock, flags);
 
         return 0;
 }
@@ -999,7 +1020,12 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
         if (!enough(conf))
                 return 0;
 
-        for (mirror=0; mirror < mddev->raid_disks; mirror++)
+        if (rdev->saved_raid_disk >= 0 &&
+            conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
+                mirror = rdev->saved_raid_disk;
+        else
+                mirror = 0;
+        for ( ; mirror < mddev->raid_disks; mirror++)
                 if ( !(p=conf->mirrors+mirror)->rdev) {
 
                         blk_queue_stack_limits(mddev->queue,
@@ -1015,6 +1041,8 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
                         p->head_position = 0;
                         rdev->raid_disk = mirror;
                         found = 1;
+                        if (rdev->saved_raid_disk != mirror)
+                                conf->fullsync = 1;
                         rcu_assign_pointer(p->rdev, rdev);
                         break;
                 }
@@ -1282,6 +1310,26 @@ static void raid10d(mddev_t *mddev)
         for (;;) {
                 char b[BDEVNAME_SIZE];
                 spin_lock_irqsave(&conf->device_lock, flags);
+
+                if (conf->pending_bio_list.head) {
+                        bio = bio_list_get(&conf->pending_bio_list);
+                        blk_remove_plug(mddev->queue);
+                        spin_unlock_irqrestore(&conf->device_lock, flags);
+                        /* flush any pending bitmap writes to disk before proceeding w/ I/O */
+                        if (bitmap_unplug(mddev->bitmap) != 0)
+                                printk("%s: bitmap file write failed!\n", mdname(mddev));
+
+                        while (bio) { /* submit pending writes */
+                                struct bio *next = bio->bi_next;
+                                bio->bi_next = NULL;
+                                generic_make_request(bio);
+                                bio = next;
+                        }
+                        unplug = 1;
+
+                        continue;
+                }
+
                 if (list_empty(head))
                         break;
                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
@@ -1388,6 +1436,8 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
         sector_t max_sector, nr_sectors;
         int disk;
         int i;
+        int max_sync;
+        int sync_blocks;
 
         sector_t sectors_skipped = 0;
         int chunks_skipped = 0;
@@ -1401,6 +1451,29 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
                 max_sector = mddev->resync_max_sectors;
         if (sector_nr >= max_sector) {
+                /* If we aborted, we need to abort the
+                 * sync on the 'current' bitmap chucks (there can
+                 * be several when recovering multiple devices).
+                 * as we may have started syncing it but not finished.
+                 * We can find the current address in
+                 * mddev->curr_resync, but for recovery,
+                 * we need to convert that to several
+                 * virtual addresses.
+                 */
+                if (mddev->curr_resync < max_sector) { /* aborted */
+                        if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
+                                bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
+                                                &sync_blocks, 1);
+                        else for (i=0; i<conf->raid_disks; i++) {
+                                sector_t sect =
+                                        raid10_find_virt(conf, mddev->curr_resync, i);
+                                bitmap_end_sync(mddev->bitmap, sect,
+                                                &sync_blocks, 1);
+                        }
+                } else /* completed sync */
+                        conf->fullsync = 0;
+
+                bitmap_close_sync(mddev->bitmap);
                 close_sync(conf);
                 *skipped = 1;
                 return sectors_skipped;
@@ -1425,8 +1498,6 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
          */
         if (!go_faster && conf->nr_waiting)
                 msleep_interruptible(1000);
-        raise_barrier(conf);
-        conf->next_resync = sector_nr;
 
         /* Again, very different code for resync and recovery.
          * Both must result in an r10bio with a list of bios that
@@ -1443,6 +1514,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
          * end_sync_write if we will want to write.
          */
 
+        max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
                 /* recovery... the complicated one */
                 int i, j, k;
@@ -1451,13 +1523,29 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                 for (i=0 ; i<conf->raid_disks; i++)
                         if (conf->mirrors[i].rdev &&
                             !test_bit(In_sync, &conf->mirrors[i].rdev->flags)) {
+                                int still_degraded = 0;
                                 /* want to reconstruct this device */
                                 r10bio_t *rb2 = r10_bio;
+                                sector_t sect = raid10_find_virt(conf, sector_nr, i);
+                                int must_sync;
+                                /* Unless we are doing a full sync, we only need
+                                 * to recover the block if it is set in the bitmap
+                                 */
+                                must_sync = bitmap_start_sync(mddev->bitmap, sect,
+                                                              &sync_blocks, 1);
+                                if (sync_blocks < max_sync)
+                                        max_sync = sync_blocks;
+                                if (!must_sync &&
+                                    !conf->fullsync) {
+                                        /* yep, skip the sync_blocks here, but don't assume
+                                         * that there will never be anything to do here
+                                         */
+                                        chunks_skipped = -1;
+                                        continue;
+                                }
 
                                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
-                                spin_lock_irq(&conf->resync_lock);
-                                if (rb2) conf->barrier++;
-                                spin_unlock_irq(&conf->resync_lock);
+                                raise_barrier(conf, rb2 != NULL);
                                 atomic_set(&r10_bio->remaining, 0);
 
                                 r10_bio->master_bio = (struct bio*)rb2;
@@ -1465,8 +1553,21 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                                         atomic_inc(&rb2->remaining);
                                 r10_bio->mddev = mddev;
                                 set_bit(R10BIO_IsRecover, &r10_bio->state);
-                                r10_bio->sector = raid10_find_virt(conf, sector_nr, i);
+                                r10_bio->sector = sect;
+
                                 raid10_find_phys(conf, r10_bio);
+                                /* Need to check if this section will still be
+                                 * degraded
+                                 */
+                                for (j=0; j<conf->copies;j++) {
+                                        int d = r10_bio->devs[j].devnum;
+                                        if (conf->mirrors[d].rdev == NULL ||
+                                            test_bit(Faulty, &conf->mirrors[d].rdev->flags))
+                                                still_degraded = 1;
+                                }
+                                must_sync = bitmap_start_sync(mddev->bitmap, sect,
+                                                              &sync_blocks, still_degraded);
+
                                 for (j=0; j<conf->copies;j++) {
                                         int d = r10_bio->devs[j].devnum;
                                         if (conf->mirrors[d].rdev &&
@@ -1526,10 +1627,22 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
         } else {
                 /* resync. Schedule a read for every block at this virt offset */
                 int count = 0;
+
+                if (!bitmap_start_sync(mddev->bitmap, sector_nr,
+                                       &sync_blocks, mddev->degraded) &&
+                    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+                        /* We can skip this block */
+                        *skipped = 1;
+                        return sync_blocks + sectors_skipped;
+                }
+                if (sync_blocks < max_sync)
+                        max_sync = sync_blocks;
                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
 
                 r10_bio->mddev = mddev;
                 atomic_set(&r10_bio->remaining, 0);
+                raise_barrier(conf, 0);
+                conf->next_resync = sector_nr;
 
                 r10_bio->master_bio = NULL;
                 r10_bio->sector = sector_nr;
@@ -1582,6 +1695,8 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
         }
 
         nr_sectors = 0;
+        if (sector_nr + max_sync < max_sector)
+                max_sector = sector_nr + max_sync;
         do {
                 struct page *page;
                 int len = PAGE_SIZE;
@@ -1821,6 +1936,26 @@ static int stop(mddev_t *mddev)
         return 0;
 }
 
+static void raid10_quiesce(mddev_t *mddev, int state)
+{
+        conf_t *conf = mddev_to_conf(mddev);
+
+        switch(state) {
+        case 1:
+                raise_barrier(conf, 0);
+                break;
+        case 0:
+                lower_barrier(conf);
+                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 raid10_personality =
 {
@@ -1835,6 +1970,7 @@ static mdk_personality_t raid10_personality =
         .hot_remove_disk= raid10_remove_disk,
         .spare_active   = raid10_spare_active,
         .sync_request   = sync_request,
+        .quiesce        = raid10_quiesce,
 };
 
 static int __init raid_init(void)