5 files changed, 111 insertions, 15 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index fceddbdfdd3d..dac6653d4cce 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -351,6 +351,7 @@ static inline unsigned long btrfs_chunk_item_size(int num_stripes)
 #define BTRFS_FS_STATE_ERROR            0
 #define BTRFS_FS_STATE_REMOUNTING       1
 #define BTRFS_FS_STATE_TRANS_ABORTED    2
+#define BTRFS_FS_STATE_DEV_REPLACING    3
 
 /* Super block flags */
 /* Errors detected */
@@ -1674,6 +1675,9 @@ struct btrfs_fs_info {
 
         atomic_t mutually_exclusive_operation_running;
 
+        struct percpu_counter bio_counter;
+        wait_queue_head_t replace_wait;
+
         struct semaphore uuid_tree_rescan_sem;
         unsigned int update_uuid_tree_gen:1;
 };
@@ -4008,6 +4012,11 @@ int btrfs_scrub_cancel_dev(struct btrfs_fs_info *info,
 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
                          struct btrfs_scrub_progress *progress);
 
+/* dev-replace.c */
+void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info);
+void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info);
+void btrfs_bio_counter_dec(struct btrfs_fs_info *fs_info);
+
 /* reada.c */
 struct reada_control {
         struct btrfs_root       *root;          /* tree to prefetch */
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index b20d59e5e5dd..ec1c3f3a775d 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -431,6 +431,35 @@ leave_no_lock:
         return ret;
 }
 
+/*
+ * blocked until all flighting bios are finished.
+ */
+static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
+{
+        s64 writers;
+        DEFINE_WAIT(wait);
+
+        set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
+        do {
+                prepare_to_wait(&fs_info->replace_wait, &wait,
+                                TASK_UNINTERRUPTIBLE);
+                writers = percpu_counter_sum(&fs_info->bio_counter);
+                if (writers)
+                        schedule();
+                finish_wait(&fs_info->replace_wait, &wait);
+        } while (writers);
+}
+
+/*
+ * we have removed target device, it is safe to allow new bios request.
+ */
+static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
+{
+        clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
+        if (waitqueue_active(&fs_info->replace_wait))
+                wake_up(&fs_info->replace_wait);
+}
+
 static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
                                        int scrub_ret)
 {
@@ -458,12 +487,6 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
         src_device = dev_replace->srcdev;
         btrfs_dev_replace_unlock(dev_replace);
 
-        /* replace old device with new one in mapping tree */
-        if (!scrub_ret)
-                btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
-                                                                src_device,
-                                                                tgt_device);
-
         /*
          * flush all outstanding I/O and inode extent mappings before the
          * copy operation is declared as being finished
@@ -495,7 +518,12 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
         dev_replace->time_stopped = get_seconds();
         dev_replace->item_needs_writeback = 1;
 
-        if (scrub_ret) {
+        /* replace old device with new one in mapping tree */
+        if (!scrub_ret) {
+                btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
+                                                                src_device,
+                                                                tgt_device);
+        } else {
                 printk_in_rcu(KERN_ERR
                               "BTRFS: btrfs_scrub_dev(%s, %llu, %s) failed %d\n",
                               src_device->missing ? "<missing disk>" :
@@ -534,8 +562,12 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
                 fs_info->fs_devices->latest_bdev = tgt_device->bdev;
         list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 
+        btrfs_rm_dev_replace_blocked(fs_info);
+
         btrfs_rm_dev_replace_srcdev(fs_info, src_device);
 
+        btrfs_rm_dev_replace_unblocked(fs_info);
+
         /*
          * this is again a consistent state where no dev_replace procedure
          * is running, the target device is part of the filesystem, the
@@ -865,3 +897,31 @@ void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
                 mutex_unlock(&dev_replace->lock_management_lock);
         }
 }
+
+void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
+{
+        percpu_counter_inc(&fs_info->bio_counter);
+}
+
+void btrfs_bio_counter_dec(struct btrfs_fs_info *fs_info)
+{
+        percpu_counter_dec(&fs_info->bio_counter);
+
+        if (waitqueue_active(&fs_info->replace_wait))
+                wake_up(&fs_info->replace_wait);
+}
+
+void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
+{
+        DEFINE_WAIT(wait);
+again:
+        percpu_counter_inc(&fs_info->bio_counter);
+        if (test_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state)) {
+                btrfs_bio_counter_dec(fs_info);
+                wait_event(fs_info->replace_wait,
+                           !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
+                                     &fs_info->fs_state));
+                goto again;
+        }
+
+}
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index fcf367581073..0cafacb07b43 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2136,10 +2136,16 @@ int open_ctree(struct super_block *sb,
                 goto fail_dirty_metadata_bytes;
         }
 
+        ret = percpu_counter_init(&fs_info->bio_counter, 0);
+        if (ret) {
+                err = ret;
+                goto fail_delalloc_bytes;
+        }
+
         fs_info->btree_inode = new_inode(sb);
         if (!fs_info->btree_inode) {
                 err = -ENOMEM;
-                goto fail_delalloc_bytes;
+                goto fail_bio_counter;
         }
 
         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
@@ -2214,6 +2220,7 @@ int open_ctree(struct super_block *sb,
         atomic_set(&fs_info->scrub_pause_req, 0);
         atomic_set(&fs_info->scrubs_paused, 0);
         atomic_set(&fs_info->scrub_cancel_req, 0);
+        init_waitqueue_head(&fs_info->replace_wait);
         init_waitqueue_head(&fs_info->scrub_pause_wait);
         fs_info->scrub_workers_refcnt = 0;
 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
@@ -2966,6 +2973,8 @@ fail_iput:
         btrfs_mapping_tree_free(&fs_info->mapping_tree);
 
         iput(fs_info->btree_inode);
+fail_bio_counter:
+        percpu_counter_destroy(&fs_info->bio_counter);
 fail_delalloc_bytes:
         percpu_counter_destroy(&fs_info->delalloc_bytes);
 fail_dirty_metadata_bytes:
@@ -3613,6 +3622,7 @@ int close_ctree(struct btrfs_root *root)
 
         percpu_counter_destroy(&fs_info->dirty_metadata_bytes);
         percpu_counter_destroy(&fs_info->delalloc_bytes);
+        percpu_counter_destroy(&fs_info->bio_counter);
         bdi_destroy(&fs_info->bdi);
         cleanup_srcu_struct(&fs_info->subvol_srcu);
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b68afe32419f..07629e99809a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5263,6 +5263,7 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
 static void btrfs_end_bio(struct bio *bio, int err)
 {
         struct btrfs_bio *bbio = bio->bi_private;
+        struct btrfs_device *dev = bbio->stripes[0].dev;
         int is_orig_bio = 0;
 
         if (err) {
@@ -5270,7 +5271,6 @@ static void btrfs_end_bio(struct bio *bio, int err)
                 if (err == -EIO || err == -EREMOTEIO) {
                         unsigned int stripe_index =
                                 btrfs_io_bio(bio)->stripe_index;
-                        struct btrfs_device *dev;
 
                         BUG_ON(stripe_index >= bbio->num_stripes);
                         dev = bbio->stripes[stripe_index].dev;
@@ -5292,6 +5292,8 @@ static void btrfs_end_bio(struct bio *bio, int err)
         if (bio == bbio->orig_bio)
                 is_orig_bio = 1;
 
+        btrfs_bio_counter_dec(bbio->fs_info);
+
         if (atomic_dec_and_test(&bbio->stripes_pending)) {
                 if (!is_orig_bio) {
                         bio_put(bio);
@@ -5440,6 +5442,9 @@ static void submit_stripe_bio(struct btrfs_root *root, struct btrfs_bio *bbio,
         }
 #endif
         bio->bi_bdev = dev->bdev;
+
+        btrfs_bio_counter_inc_noblocked(root->fs_info);
+
         if (async)
                 btrfs_schedule_bio(root, dev, rw, bio);
         else
@@ -5508,28 +5513,38 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
         length = bio->bi_size;
         map_length = length;
 
+        btrfs_bio_counter_inc_blocked(root->fs_info);
         ret = __btrfs_map_block(root->fs_info, rw, logical, &map_length, &bbio,
                               mirror_num, &raid_map);
-        if (ret) /* -ENOMEM */
+        if (ret) {
+                btrfs_bio_counter_dec(root->fs_info);
                 return ret;
+        }
 
         total_devs = bbio->num_stripes;
         bbio->orig_bio = first_bio;
         bbio->private = first_bio->bi_private;
         bbio->end_io = first_bio->bi_end_io;
+        bbio->fs_info = root->fs_info;
         atomic_set(&bbio->stripes_pending, bbio->num_stripes);
 
         if (raid_map) {
                 /* In this case, map_length has been set to the length of
                    a single stripe; not the whole write */
                 if (rw & WRITE) {
-                        return raid56_parity_write(root, bio, bbio,
-                                                   raid_map, map_length);
+                        ret = raid56_parity_write(root, bio, bbio,
+                                                  raid_map, map_length);
                 } else {
-                        return raid56_parity_recover(root, bio, bbio,
-                                                     raid_map, map_length,
-                                                     mirror_num);
+                        ret = raid56_parity_recover(root, bio, bbio,
+                                                    raid_map, map_length,
+                                                    mirror_num);
                 }
+                /*
+                 * FIXME, replace dosen't support raid56 yet, please fix
+                 * it in the future.
+                 */
+                btrfs_bio_counter_dec(root->fs_info);
+                return ret;
         }
 
         if (map_length < length) {
@@ -5571,6 +5586,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
                                   async_submit);
                 dev_nr++;
         }
+        btrfs_bio_counter_dec(root->fs_info);
         return 0;
 }
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 8b3cd142b373..80754f9dd3df 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -192,6 +192,7 @@ typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err);
 
 struct btrfs_bio {
         atomic_t stripes_pending;
+        struct btrfs_fs_info *fs_info;
         bio_end_io_t *end_io;
         struct bio *orig_bio;
         void *private;