1 files changed, 112 insertions, 93 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 04348d76bb30..259f519814ca 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -99,34 +99,40 @@ static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
  * We maintain a biased count of active stripes in the bottom 16 bits of
  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
  */
-static inline int raid5_bi_phys_segments(struct bio *bio)
+static inline int raid5_bi_processed_stripes(struct bio *bio)
 {
-        return bio->bi_phys_segments & 0xffff;
+        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
+        return (atomic_read(segments) >> 16) & 0xffff;
 }
 
-static inline int raid5_bi_hw_segments(struct bio *bio)
+static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 {
-        return (bio->bi_phys_segments >> 16) & 0xffff;
+        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
+        return atomic_sub_return(1, segments) & 0xffff;
 }
 
-static inline int raid5_dec_bi_phys_segments(struct bio *bio)
+static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 {
-        --bio->bi_phys_segments;
-        return raid5_bi_phys_segments(bio);
+        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
+        atomic_inc(segments);
 }
 
-static inline int raid5_dec_bi_hw_segments(struct bio *bio)
+static inline void raid5_set_bi_processed_stripes(struct bio *bio,
+        unsigned int cnt)
 {
-        unsigned short val = raid5_bi_hw_segments(bio);
+        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
+        int old, new;
 
-        --val;
-        bio->bi_phys_segments = (val << 16) | raid5_bi_phys_segments(bio);
-        return val;
+        do {
+                old = atomic_read(segments);
+                new = (old & 0xffff) | (cnt << 16);
+        } while (atomic_cmpxchg(segments, old, new) != old);
 }
 
-static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
+static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 {
-        bio->bi_phys_segments = raid5_bi_phys_segments(bio) | (cnt << 16);
+        atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
+        atomic_set(segments, cnt);
 }
 
 /* Find first data disk in a raid6 stripe */
@@ -190,49 +196,56 @@ static int stripe_operations_active(struct stripe_head *sh)
                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 }
 
-static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
+static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh)
 {
-        if (atomic_dec_and_test(&sh->count)) {
-                BUG_ON(!list_empty(&sh->lru));
-                BUG_ON(atomic_read(&conf->active_stripes)==0);
-                if (test_bit(STRIPE_HANDLE, &sh->state)) {
-                        if (test_bit(STRIPE_DELAYED, &sh->state) &&
-                            !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
-                                list_add_tail(&sh->lru, &conf->delayed_list);
-                        else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
-                                   sh->bm_seq - conf->seq_write > 0)
-                                list_add_tail(&sh->lru, &conf->bitmap_list);
-                        else {
-                                clear_bit(STRIPE_DELAYED, &sh->state);
-                                clear_bit(STRIPE_BIT_DELAY, &sh->state);
-                                list_add_tail(&sh->lru, &conf->handle_list);
-                        }
-                        md_wakeup_thread(conf->mddev->thread);
-                } else {
-                        BUG_ON(stripe_operations_active(sh));
-                        if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
-                                if (atomic_dec_return(&conf->preread_active_stripes)
-                                    < IO_THRESHOLD)
-                                        md_wakeup_thread(conf->mddev->thread);
-                        atomic_dec(&conf->active_stripes);
-                        if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
-                                list_add_tail(&sh->lru, &conf->inactive_list);
-                                wake_up(&conf->wait_for_stripe);
-                                if (conf->retry_read_aligned)
-                                        md_wakeup_thread(conf->mddev->thread);
-                        }
+        BUG_ON(!list_empty(&sh->lru));
+        BUG_ON(atomic_read(&conf->active_stripes)==0);
+        if (test_bit(STRIPE_HANDLE, &sh->state)) {
+                if (test_bit(STRIPE_DELAYED, &sh->state) &&
+                    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+                        list_add_tail(&sh->lru, &conf->delayed_list);
+                else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
+                           sh->bm_seq - conf->seq_write > 0)
+                        list_add_tail(&sh->lru, &conf->bitmap_list);
+                else {
+                        clear_bit(STRIPE_DELAYED, &sh->state);
+                        clear_bit(STRIPE_BIT_DELAY, &sh->state);
+                        list_add_tail(&sh->lru, &conf->handle_list);
+                }
+                md_wakeup_thread(conf->mddev->thread);
+        } else {
+                BUG_ON(stripe_operations_active(sh));
+                if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+                        if (atomic_dec_return(&conf->preread_active_stripes)
+                            < IO_THRESHOLD)
+                                md_wakeup_thread(conf->mddev->thread);
+                atomic_dec(&conf->active_stripes);
+                if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
+                        list_add_tail(&sh->lru, &conf->inactive_list);
+                        wake_up(&conf->wait_for_stripe);
+                        if (conf->retry_read_aligned)
+                                md_wakeup_thread(conf->mddev->thread);
                 }
         }
 }
 
+static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
+{
+        if (atomic_dec_and_test(&sh->count))
+                do_release_stripe(conf, sh);
+}
+
 static void release_stripe(struct stripe_head *sh)
 {
         struct r5conf *conf = sh->raid_conf;
         unsigned long flags;
 
-        spin_lock_irqsave(&conf->device_lock, flags);
-        __release_stripe(conf, sh);
-        spin_unlock_irqrestore(&conf->device_lock, flags);
+        local_irq_save(flags);
+        if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
+                do_release_stripe(conf, sh);
+                spin_unlock(&conf->device_lock);
+        }
+        local_irq_restore(flags);
 }
 
 static inline void remove_hash(struct stripe_head *sh)
@@ -640,6 +653,9 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
                         else
                                 bi->bi_sector = (sh->sector
                                                  + rdev->data_offset);
+                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
+                                bi->bi_rw |= REQ_FLUSH;
+
                         bi->bi_flags = 1 << BIO_UPTODATE;
                         bi->bi_idx = 0;
                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
@@ -749,14 +765,12 @@ static void ops_complete_biofill(void *stripe_head_ref)
 {
         struct stripe_head *sh = stripe_head_ref;
         struct bio *return_bi = NULL;
-        struct r5conf *conf = sh->raid_conf;
         int i;
 
         pr_debug("%s: stripe %llu\n", __func__,
                 (unsigned long long)sh->sector);
 
         /* clear completed biofills */
-        spin_lock_irq(&conf->device_lock);
         for (i = sh->disks; i--; ) {
                 struct r5dev *dev = &sh->dev[i];
 
@@ -774,7 +788,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
                         while (rbi && rbi->bi_sector <
                                 dev->sector + STRIPE_SECTORS) {
                                 rbi2 = r5_next_bio(rbi, dev->sector);
-                                if (!raid5_dec_bi_phys_segments(rbi)) {
+                                if (!raid5_dec_bi_active_stripes(rbi)) {
                                         rbi->bi_next = return_bi;
                                         return_bi = rbi;
                                 }
@@ -782,7 +796,6 @@ static void ops_complete_biofill(void *stripe_head_ref)
                         }
                 }
         }
-        spin_unlock_irq(&conf->device_lock);
         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
 
         return_io(return_bi);
@@ -794,7 +807,6 @@ static void ops_complete_biofill(void *stripe_head_ref)
 static void ops_run_biofill(struct stripe_head *sh)
 {
         struct dma_async_tx_descriptor *tx = NULL;
-        struct r5conf *conf = sh->raid_conf;
         struct async_submit_ctl submit;
         int i;
 
@@ -805,10 +817,10 @@ static void ops_run_biofill(struct stripe_head *sh)
                 struct r5dev *dev = &sh->dev[i];
                 if (test_bit(R5_Wantfill, &dev->flags)) {
                         struct bio *rbi;
-                        spin_lock_irq(&conf->device_lock);
+                        spin_lock_irq(&sh->stripe_lock);
                         dev->read = rbi = dev->toread;
                         dev->toread = NULL;
-                        spin_unlock_irq(&conf->device_lock);
+                        spin_unlock_irq(&sh->stripe_lock);
                         while (rbi && rbi->bi_sector <
                                 dev->sector + STRIPE_SECTORS) {
                                 tx = async_copy_data(0, rbi, dev->page,
@@ -1144,12 +1156,12 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
                         struct bio *wbi;
 
-                        spin_lock_irq(&sh->raid_conf->device_lock);
+                        spin_lock_irq(&sh->stripe_lock);
                         chosen = dev->towrite;
                         dev->towrite = NULL;
                         BUG_ON(dev->written);
                         wbi = dev->written = chosen;
-                        spin_unlock_irq(&sh->raid_conf->device_lock);
+                        spin_unlock_irq(&sh->stripe_lock);
 
                         while (wbi && wbi->bi_sector <
                                 dev->sector + STRIPE_SECTORS) {
@@ -1454,6 +1466,8 @@ static int grow_one_stripe(struct r5conf *conf)
         init_waitqueue_head(&sh->ops.wait_for_ops);
         #endif
 
+        spin_lock_init(&sh->stripe_lock);
+
         if (grow_buffers(sh)) {
                 shrink_buffers(sh);
                 kmem_cache_free(conf->slab_cache, sh);
@@ -1739,7 +1753,9 @@ static void raid5_end_read_request(struct bio * bi, int error)
                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
                         clear_bit(R5_ReadError, &sh->dev[i].flags);
                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
-                }
+                } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
+                        clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
+
                 if (atomic_read(&rdev->read_errors))
                         atomic_set(&rdev->read_errors, 0);
         } else {
@@ -1784,7 +1800,11 @@ static void raid5_end_read_request(struct bio * bi, int error)
                 else
                         retry = 1;
                 if (retry)
-                        set_bit(R5_ReadError, &sh->dev[i].flags);
+                        if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
+                                set_bit(R5_ReadError, &sh->dev[i].flags);
+                                clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
+                        } else
+                                set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
                 else {
                         clear_bit(R5_ReadError, &sh->dev[i].flags);
                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
@@ -2340,11 +2360,18 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
                 (unsigned long long)bi->bi_sector,
                 (unsigned long long)sh->sector);
 
-
-        spin_lock_irq(&conf->device_lock);
+        /*
+         * If several bio share a stripe. The bio bi_phys_segments acts as a
+         * reference count to avoid race. The reference count should already be
+         * increased before this function is called (for example, in
+         * make_request()), so other bio sharing this stripe will not free the
+         * stripe. If a stripe is owned by one stripe, the stripe lock will
+         * protect it.
+         */
+        spin_lock_irq(&sh->stripe_lock);
         if (forwrite) {
                 bip = &sh->dev[dd_idx].towrite;
-                if (*bip == NULL && sh->dev[dd_idx].written == NULL)
+                if (*bip == NULL)
                         firstwrite = 1;
         } else
                 bip = &sh->dev[dd_idx].toread;
@@ -2360,7 +2387,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
         if (*bip)
                 bi->bi_next = *bip;
         *bip = bi;
-        bi->bi_phys_segments++;
+        raid5_inc_bi_active_stripes(bi);
 
         if (forwrite) {
                 /* check if page is covered */
@@ -2375,7 +2402,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
         }
-        spin_unlock_irq(&conf->device_lock);
+        spin_unlock_irq(&sh->stripe_lock);
 
         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
                 (unsigned long long)(*bip)->bi_sector,
@@ -2391,7 +2418,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
 
  overlap:
         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
-        spin_unlock_irq(&conf->device_lock);
+        spin_unlock_irq(&sh->stripe_lock);
         return 0;
 }
 
@@ -2441,10 +2468,11 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
                                 rdev_dec_pending(rdev, conf->mddev);
                         }
                 }
-                spin_lock_irq(&conf->device_lock);
+                spin_lock_irq(&sh->stripe_lock);
                 /* fail all writes first */
                 bi = sh->dev[i].towrite;
                 sh->dev[i].towrite = NULL;
+                spin_unlock_irq(&sh->stripe_lock);
                 if (bi) {
                         s->to_write--;
                         bitmap_end = 1;
@@ -2457,13 +2485,17 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
                         sh->dev[i].sector + STRIPE_SECTORS) {
                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
-                        if (!raid5_dec_bi_phys_segments(bi)) {
+                        if (!raid5_dec_bi_active_stripes(bi)) {
                                 md_write_end(conf->mddev);
                                 bi->bi_next = *return_bi;
                                 *return_bi = bi;
                         }
                         bi = nextbi;
                 }
+                if (bitmap_end)
+                        bitmap_endwrite(conf->mddev->bitmap, sh->sector,
+                                STRIPE_SECTORS, 0, 0);
+                bitmap_end = 0;
                 /* and fail all 'written' */
                 bi = sh->dev[i].written;
                 sh->dev[i].written = NULL;
@@ -2472,7 +2504,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
                        sh->dev[i].sector + STRIPE_SECTORS) {
                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
-                        if (!raid5_dec_bi_phys_segments(bi)) {
+                        if (!raid5_dec_bi_active_stripes(bi)) {
                                 md_write_end(conf->mddev);
                                 bi->bi_next = *return_bi;
                                 *return_bi = bi;
@@ -2496,14 +2528,13 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
                                 struct bio *nextbi =
                                         r5_next_bio(bi, sh->dev[i].sector);
                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
-                                if (!raid5_dec_bi_phys_segments(bi)) {
+                                if (!raid5_dec_bi_active_stripes(bi)) {
                                         bi->bi_next = *return_bi;
                                         *return_bi = bi;
                                 }
                                 bi = nextbi;
                         }
                 }
-                spin_unlock_irq(&conf->device_lock);
                 if (bitmap_end)
                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
                                         STRIPE_SECTORS, 0, 0);
@@ -2707,30 +2738,23 @@ static void handle_stripe_clean_event(struct r5conf *conf,
                                 test_bit(R5_UPTODATE, &dev->flags)) {
                                 /* We can return any write requests */
                                 struct bio *wbi, *wbi2;
-                                int bitmap_end = 0;
                                 pr_debug("Return write for disc %d\n", i);
-                                spin_lock_irq(&conf->device_lock);
                                 wbi = dev->written;
                                 dev->written = NULL;
                                 while (wbi && wbi->bi_sector <
                                         dev->sector + STRIPE_SECTORS) {
                                         wbi2 = r5_next_bio(wbi, dev->sector);
-                                        if (!raid5_dec_bi_phys_segments(wbi)) {
+                                        if (!raid5_dec_bi_active_stripes(wbi)) {
                                                 md_write_end(conf->mddev);
                                                 wbi->bi_next = *return_bi;
                                                 *return_bi = wbi;
                                         }
                                         wbi = wbi2;
                                 }
-                                if (dev->towrite == NULL)
-                                        bitmap_end = 1;
-                                spin_unlock_irq(&conf->device_lock);
-                                if (bitmap_end)
-                                        bitmap_endwrite(conf->mddev->bitmap,
-                                                        sh->sector,
-                                                        STRIPE_SECTORS,
+                                bitmap_endwrite(conf->mddev->bitmap, sh->sector,
+                                                STRIPE_SECTORS,
                                          !test_bit(STRIPE_DEGRADED, &sh->state),
-                                                        0);
+                                                0);
                         }
                 }
 
@@ -3182,7 +3206,6 @@ static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
 
         /* Now to look around and see what can be done */
         rcu_read_lock();
-        spin_lock_irq(&conf->device_lock);
         for (i=disks; i--; ) {
                 struct md_rdev *rdev;
                 sector_t first_bad;
@@ -3328,7 +3351,6 @@ static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
                                 do_recovery = 1;
                 }
         }
-        spin_unlock_irq(&conf->device_lock);
         if (test_bit(STRIPE_SYNCING, &sh->state)) {
                 /* If there is a failed device being replaced,
                  *     we must be recovering.
@@ -3791,7 +3813,7 @@ static struct bio *remove_bio_from_retry(struct r5conf *conf)
                  * this sets the active strip count to 1 and the processed
                  * strip count to zero (upper 8 bits)
                  */
-                bi->bi_phys_segments = 1; /* biased count of active stripes */
+                raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
         }
 
         return bi;
@@ -4113,7 +4135,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
                         finish_wait(&conf->wait_for_overlap, &w);
                         set_bit(STRIPE_HANDLE, &sh->state);
                         clear_bit(STRIPE_DELAYED, &sh->state);
-                        if ((bi->bi_rw & REQ_SYNC) &&
+                        if ((bi->bi_rw & REQ_NOIDLE) &&
                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
                                 atomic_inc(&conf->preread_active_stripes);
                         mddev_check_plugged(mddev);
@@ -4126,9 +4148,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
                 }
         }
 
-        spin_lock_irq(&conf->device_lock);
-        remaining = raid5_dec_bi_phys_segments(bi);
-        spin_unlock_irq(&conf->device_lock);
+        remaining = raid5_dec_bi_active_stripes(bi);
         if (remaining == 0) {
 
                 if ( rw == WRITE )
@@ -4484,7 +4504,7 @@ static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
                      sector += STRIPE_SECTORS,
                      scnt++) {
 
-                if (scnt < raid5_bi_hw_segments(raid_bio))
+                if (scnt < raid5_bi_processed_stripes(raid_bio))
                         /* already done this stripe */
                         continue;
 
@@ -4492,25 +4512,24 @@ static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
 
                 if (!sh) {
                         /* failed to get a stripe - must wait */
-                        raid5_set_bi_hw_segments(raid_bio, scnt);
+                        raid5_set_bi_processed_stripes(raid_bio, scnt);
                         conf->retry_read_aligned = raid_bio;
                         return handled;
                 }
 
                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
                         release_stripe(sh);
-                        raid5_set_bi_hw_segments(raid_bio, scnt);
+                        raid5_set_bi_processed_stripes(raid_bio, scnt);
                         conf->retry_read_aligned = raid_bio;
                         return handled;
                 }
 
+                set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
                 handle_stripe(sh);
                 release_stripe(sh);
                 handled++;
         }
-        spin_lock_irq(&conf->device_lock);
-        remaining = raid5_dec_bi_phys_segments(raid_bio);
-        spin_unlock_irq(&conf->device_lock);
+        remaining = raid5_dec_bi_active_stripes(raid_bio);
         if (remaining == 0)
                 bio_endio(raid_bio, 0);
         if (atomic_dec_and_test(&conf->active_aligned_reads))