1 files changed, 245 insertions, 156 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 71cd456fdb6..f5be06a2462 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -320,12 +320,12 @@ static u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
         return total_added;
 }
 
-static int caching_kthread(void *data)
+static noinline void caching_thread(struct btrfs_work *work)
 {
-        struct btrfs_block_group_cache *block_group = data;
-        struct btrfs_fs_info *fs_info = block_group->fs_info;
-        struct btrfs_caching_control *caching_ctl = block_group->caching_ctl;
-        struct btrfs_root *extent_root = fs_info->extent_root;
+        struct btrfs_block_group_cache *block_group;
+        struct btrfs_fs_info *fs_info;
+        struct btrfs_caching_control *caching_ctl;
+        struct btrfs_root *extent_root;
         struct btrfs_path *path;
         struct extent_buffer *leaf;
         struct btrfs_key key;
@@ -334,9 +334,14 @@ static int caching_kthread(void *data)
         u32 nritems;
         int ret = 0;
 
+        caching_ctl = container_of(work, struct btrfs_caching_control, work);
+        block_group = caching_ctl->block_group;
+        fs_info = block_group->fs_info;
+        extent_root = fs_info->extent_root;
+
         path = btrfs_alloc_path();
         if (!path)
-                return -ENOMEM;
+                goto out;
 
         last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
 
@@ -433,13 +438,11 @@ err:
         free_excluded_extents(extent_root, block_group);
 
         mutex_unlock(&caching_ctl->mutex);
+out:
         wake_up(&caching_ctl->wait);
 
         put_caching_control(caching_ctl);
-        atomic_dec(&block_group->space_info->caching_threads);
         btrfs_put_block_group(block_group);
-
-        return 0;
 }
 
 static int cache_block_group(struct btrfs_block_group_cache *cache,
@@ -449,7 +452,6 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
 {
         struct btrfs_fs_info *fs_info = cache->fs_info;
         struct btrfs_caching_control *caching_ctl;
-        struct task_struct *tsk;
         int ret = 0;
 
         smp_mb();
@@ -501,6 +503,7 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
         caching_ctl->progress = cache->key.objectid;
         /* one for caching kthread, one for caching block group list */
         atomic_set(&caching_ctl->count, 2);
+        caching_ctl->work.func = caching_thread;
 
         spin_lock(&cache->lock);
         if (cache->cached != BTRFS_CACHE_NO) {
@@ -516,16 +519,9 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
         list_add_tail(&caching_ctl->list, &fs_info->caching_block_groups);
         up_write(&fs_info->extent_commit_sem);
 
-        atomic_inc(&cache->space_info->caching_threads);
         btrfs_get_block_group(cache);
 
-        tsk = kthread_run(caching_kthread, cache, "btrfs-cache-%llu\n",
-                          cache->key.objectid);
-        if (IS_ERR(tsk)) {
-                ret = PTR_ERR(tsk);
-                printk(KERN_ERR "error running thread %d\n", ret);
-                BUG();
-        }
+        btrfs_queue_worker(&fs_info->caching_workers, &caching_ctl->work);
 
         return ret;
 }
@@ -667,7 +663,9 @@ int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len)
         struct btrfs_path *path;
 
         path = btrfs_alloc_path();
-        BUG_ON(!path);
+        if (!path)
+                return -ENOMEM;
+
         key.objectid = start;
         key.offset = len;
         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
@@ -1784,6 +1782,9 @@ static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
 
 
                 for (i = 0; i < multi->num_stripes; i++, stripe++) {
+                        if (!stripe->dev->can_discard)
+                                continue;
+
                         ret = btrfs_issue_discard(stripe->dev->bdev,
                                                   stripe->physical,
                                                   stripe->length);
@@ -1791,11 +1792,16 @@ static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
                                 discarded_bytes += stripe->length;
                         else if (ret != -EOPNOTSUPP)
                                 break;
+
+                        /*
+                         * Just in case we get back EOPNOTSUPP for some reason,
+                         * just ignore the return value so we don't screw up
+                         * people calling discard_extent.
+                         */
+                        ret = 0;
                 }
                 kfree(multi);
         }
-        if (discarded_bytes && ret == -EOPNOTSUPP)
-                ret = 0;
 
         if (actual_bytes)
                 *actual_bytes = discarded_bytes;
@@ -2932,9 +2938,10 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
         found->full = 0;
         found->force_alloc = CHUNK_ALLOC_NO_FORCE;
         found->chunk_alloc = 0;
+        found->flush = 0;
+        init_waitqueue_head(&found->wait);
         *space_info = found;
         list_add_rcu(&found->list, &info->space_info);
-        atomic_set(&found->caching_threads, 0);
         return 0;
 }
 
@@ -3275,6 +3282,9 @@ again:
         }
 
         ret = btrfs_alloc_chunk(trans, extent_root, flags);
+        if (ret < 0 && ret != -ENOSPC)
+                goto out;
+
         spin_lock(&space_info->lock);
         if (ret)
                 space_info->full = 1;
@@ -3284,6 +3294,7 @@ again:
         space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
         space_info->chunk_alloc = 0;
         spin_unlock(&space_info->lock);
+out:
         mutex_unlock(&extent_root->fs_info->chunk_mutex);
         return ret;
 }
@@ -3314,6 +3325,14 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
         if (reserved == 0)
                 return 0;
 
+        smp_mb();
+        if (root->fs_info->delalloc_bytes == 0) {
+                if (trans)
+                        return 0;
+                btrfs_wait_ordered_extents(root, 0, 0);
+                return 0;
+        }
+
         max_reclaim = min(reserved, to_reclaim);
 
         while (loops < 1024) {
@@ -3356,6 +3375,8 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
                 }
 
         }
+        if (reclaimed >= to_reclaim && !trans)
+                btrfs_wait_ordered_extents(root, 0, 0);
         return reclaimed >= to_reclaim;
 }
 
@@ -3380,15 +3401,36 @@ static int reserve_metadata_bytes(struct btrfs_trans_handle *trans,
         u64 num_bytes = orig_bytes;
         int retries = 0;
         int ret = 0;
-        bool reserved = false;
         bool committed = false;
+        bool flushing = false;
 
 again:
-        ret = -ENOSPC;
-        if (reserved)
-                num_bytes = 0;
-
+        ret = 0;
         spin_lock(&space_info->lock);
+        /*
+         * We only want to wait if somebody other than us is flushing and we are
+         * actually alloed to flush.
+         */
+        while (flush && !flushing && space_info->flush) {
+                spin_unlock(&space_info->lock);
+                /*
+                 * If we have a trans handle we can't wait because the flusher
+                 * may have to commit the transaction, which would mean we would
+                 * deadlock since we are waiting for the flusher to finish, but
+                 * hold the current transaction open.
+                 */
+                if (trans)
+                        return -EAGAIN;
+                ret = wait_event_interruptible(space_info->wait,
+                                               !space_info->flush);
+                /* Must have been interrupted, return */
+                if (ret)
+                        return -EINTR;
+
+                spin_lock(&space_info->lock);
+        }
+
+        ret = -ENOSPC;
         unused = space_info->bytes_used + space_info->bytes_reserved +
                  space_info->bytes_pinned + space_info->bytes_readonly +
                  space_info->bytes_may_use;
@@ -3403,8 +3445,7 @@ again:
         if (unused <= space_info->total_bytes) {
                 unused = space_info->total_bytes - unused;
                 if (unused >= num_bytes) {
-                        if (!reserved)
-                                space_info->bytes_reserved += orig_bytes;
+                        space_info->bytes_reserved += orig_bytes;
                         ret = 0;
                 } else {
                         /*
@@ -3429,17 +3470,14 @@ again:
          * to reclaim space we can actually use it instead of somebody else
          * stealing it from us.
          */
-        if (ret && !reserved) {
-                space_info->bytes_reserved += orig_bytes;
-                reserved = true;
+        if (ret && flush) {
+                flushing = true;
+                space_info->flush = 1;
         }
 
         spin_unlock(&space_info->lock);
 
-        if (!ret)
-                return 0;
-
-        if (!flush)
+        if (!ret || !flush)
                 goto out;
 
         /*
@@ -3447,11 +3485,11 @@ again:
          * metadata until after the IO is completed.
          */
         ret = shrink_delalloc(trans, root, num_bytes, 1);
-        if (ret > 0)
-                return 0;
-        else if (ret < 0)
+        if (ret < 0)
                 goto out;
 
+        ret = 0;
+
         /*
          * So if we were overcommitted it's possible that somebody else flushed
          * out enough space and we simply didn't have enough space to reclaim,
@@ -3462,11 +3500,11 @@ again:
                 goto again;
         }
 
-        spin_lock(&space_info->lock);
         /*
          * Not enough space to be reclaimed, don't bother committing the
          * transaction.
          */
+        spin_lock(&space_info->lock);
         if (space_info->bytes_pinned < orig_bytes)
                 ret = -ENOSPC;
         spin_unlock(&space_info->lock);
@@ -3474,10 +3512,13 @@ again:
                 goto out;
 
         ret = -EAGAIN;
-        if (trans || committed)
+        if (trans)
                 goto out;
 
         ret = -ENOSPC;
+        if (committed)
+                goto out;
+
         trans = btrfs_join_transaction(root);
         if (IS_ERR(trans))
                 goto out;
@@ -3489,12 +3530,12 @@ again:
         }
 
 out:
-        if (reserved) {
+        if (flushing) {
                 spin_lock(&space_info->lock);
-                space_info->bytes_reserved -= orig_bytes;
+                space_info->flush = 0;
+                wake_up_all(&space_info->wait);
                 spin_unlock(&space_info->lock);
         }
-
         return ret;
 }
 
@@ -3704,7 +3745,6 @@ int btrfs_block_rsv_check(struct btrfs_trans_handle *trans,
         if (commit_trans) {
                 if (trans)
                         return -EAGAIN;
-
                 trans = btrfs_join_transaction(root);
                 BUG_ON(IS_ERR(trans));
                 ret = btrfs_commit_transaction(trans, root);
@@ -3874,26 +3914,6 @@ int btrfs_truncate_reserve_metadata(struct btrfs_trans_handle *trans,
         return 0;
 }
 
-int btrfs_trans_reserve_metadata(struct btrfs_trans_handle *trans,
-                                 struct btrfs_root *root,
-                                 int num_items)
-{
-        u64 num_bytes;
-        int ret;
-
-        if (num_items == 0 || root->fs_info->chunk_root == root)
-                return 0;
-
-        num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
-        ret = btrfs_block_rsv_add(trans, root, &root->fs_info->trans_block_rsv,
-                                  num_bytes);
-        if (!ret) {
-                trans->bytes_reserved += num_bytes;
-                trans->block_rsv = &root->fs_info->trans_block_rsv;
-        }
-        return ret;
-}
-
 void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
                                   struct btrfs_root *root)
 {
@@ -3944,6 +3964,30 @@ int btrfs_snap_reserve_metadata(struct btrfs_trans_handle *trans,
         return block_rsv_migrate_bytes(src_rsv, dst_rsv, num_bytes);
 }
 
+static unsigned drop_outstanding_extent(struct inode *inode)
+{
+        unsigned dropped_extents = 0;
+
+        spin_lock(&BTRFS_I(inode)->lock);
+        BUG_ON(!BTRFS_I(inode)->outstanding_extents);
+        BTRFS_I(inode)->outstanding_extents--;
+
+        /*
+         * If we have more or the same amount of outsanding extents than we have
+         * reserved then we need to leave the reserved extents count alone.
+         */
+        if (BTRFS_I(inode)->outstanding_extents >=
+            BTRFS_I(inode)->reserved_extents)
+                goto out;
+
+        dropped_extents = BTRFS_I(inode)->reserved_extents -
+                BTRFS_I(inode)->outstanding_extents;
+        BTRFS_I(inode)->reserved_extents -= dropped_extents;
+out:
+        spin_unlock(&BTRFS_I(inode)->lock);
+        return dropped_extents;
+}
+
 static u64 calc_csum_metadata_size(struct inode *inode, u64 num_bytes)
 {
         return num_bytes >>= 3;
@@ -3953,9 +3997,8 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_block_rsv *block_rsv = &root->fs_info->delalloc_block_rsv;
-        u64 to_reserve;
-        int nr_extents;
-        int reserved_extents;
+        u64 to_reserve = 0;
+        unsigned nr_extents = 0;
         int ret;
 
         if (btrfs_transaction_in_commit(root->fs_info))
@@ -3963,66 +4006,49 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
 
         num_bytes = ALIGN(num_bytes, root->sectorsize);
 
-        nr_extents = atomic_read(&BTRFS_I(inode)->outstanding_extents) + 1;
-        reserved_extents = atomic_read(&BTRFS_I(inode)->reserved_extents);
+        spin_lock(&BTRFS_I(inode)->lock);
+        BTRFS_I(inode)->outstanding_extents++;
+
+        if (BTRFS_I(inode)->outstanding_extents >
+            BTRFS_I(inode)->reserved_extents) {
+                nr_extents = BTRFS_I(inode)->outstanding_extents -
+                        BTRFS_I(inode)->reserved_extents;
+                BTRFS_I(inode)->reserved_extents += nr_extents;
 
-        if (nr_extents > reserved_extents) {
-                nr_extents -= reserved_extents;
                 to_reserve = btrfs_calc_trans_metadata_size(root, nr_extents);
-        } else {
-                nr_extents = 0;
-                to_reserve = 0;
         }
+        spin_unlock(&BTRFS_I(inode)->lock);
 
         to_reserve += calc_csum_metadata_size(inode, num_bytes);
         ret = reserve_metadata_bytes(NULL, root, block_rsv, to_reserve, 1);
-        if (ret)
+        if (ret) {
+                unsigned dropped;
+                /*
+                 * We don't need the return value since our reservation failed,
+                 * we just need to clean up our counter.
+                 */
+                dropped = drop_outstanding_extent(inode);
+                WARN_ON(dropped > 1);
                 return ret;
-
-        atomic_add(nr_extents, &BTRFS_I(inode)->reserved_extents);
-        atomic_inc(&BTRFS_I(inode)->outstanding_extents);
+        }
 
         block_rsv_add_bytes(block_rsv, to_reserve, 1);
 
-        if (block_rsv->size > 512 * 1024 * 1024)
-                shrink_delalloc(NULL, root, to_reserve, 0);
-
         return 0;
 }
 
 void btrfs_delalloc_release_metadata(struct inode *inode, u64 num_bytes)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
-        u64 to_free;
-        int nr_extents;
-        int reserved_extents;
+        u64 to_free = 0;
+        unsigned dropped;
 
         num_bytes = ALIGN(num_bytes, root->sectorsize);
-        atomic_dec(&BTRFS_I(inode)->outstanding_extents);
-        WARN_ON(atomic_read(&BTRFS_I(inode)->outstanding_extents) < 0);
-
-        reserved_extents = atomic_read(&BTRFS_I(inode)->reserved_extents);
-        do {
-                int old, new;
-
-                nr_extents = atomic_read(&BTRFS_I(inode)->outstanding_extents);
-                if (nr_extents >= reserved_extents) {
-                        nr_extents = 0;
-                        break;
-                }
-                old = reserved_extents;
-                nr_extents = reserved_extents - nr_extents;
-                new = reserved_extents - nr_extents;
-                old = atomic_cmpxchg(&BTRFS_I(inode)->reserved_extents,
-                                     reserved_extents, new);
-                if (likely(old == reserved_extents))
-                        break;
-                reserved_extents = old;
-        } while (1);
+        dropped = drop_outstanding_extent(inode);
 
         to_free = calc_csum_metadata_size(inode, num_bytes);
-        if (nr_extents > 0)
-                to_free += btrfs_calc_trans_metadata_size(root, nr_extents);
+        if (dropped > 0)
+                to_free += btrfs_calc_trans_metadata_size(root, dropped);
 
         btrfs_block_rsv_release(root, &root->fs_info->delalloc_block_rsv,
                                 to_free);
@@ -4444,7 +4470,9 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
                                 printk(KERN_ERR "umm, got %d back from search"
                                        ", was looking for %llu\n", ret,
                                        (unsigned long long)bytenr);
-                                btrfs_print_leaf(extent_root, path->nodes[0]);
+                                if (ret > 0)
+                                        btrfs_print_leaf(extent_root,
+                                                         path->nodes[0]);
                         }
                         BUG_ON(ret);
                         extent_slot = path->slots[0];
@@ -4990,14 +5018,10 @@ have_block_group:
                         }
 
                         /*
-                         * We only want to start kthread caching if we are at
-                         * the point where we will wait for caching to make
-                         * progress, or if our ideal search is over and we've
-                         * found somebody to start caching.
+                         * The caching workers are limited to 2 threads, so we
+                         * can queue as much work as we care to.
                          */
-                        if (loop > LOOP_CACHING_NOWAIT ||
-                            (loop > LOOP_FIND_IDEAL &&
-                             atomic_read(&space_info->caching_threads) < 2)) {
+                        if (loop > LOOP_FIND_IDEAL) {
                                 ret = cache_block_group(block_group, trans,
                                                         orig_root, 0);
                                 BUG_ON(ret);
@@ -5065,7 +5089,9 @@ have_block_group:
                          * group is does point to and try again
                          */
                         if (!last_ptr_loop && last_ptr->block_group &&
-                            last_ptr->block_group != block_group) {
+                            last_ptr->block_group != block_group &&
+                            index <=
+                                 get_block_group_index(last_ptr->block_group)) {
 
                                 btrfs_put_block_group(block_group);
                                 block_group = last_ptr->block_group;
@@ -5219,8 +5245,7 @@ loop:
                 if (loop == LOOP_FIND_IDEAL && found_uncached_bg) {
                         found_uncached_bg = false;
                         loop++;
-                        if (!ideal_cache_percent &&
-                            atomic_read(&space_info->caching_threads))
+                        if (!ideal_cache_percent)
                                 goto search;
 
                         /*
@@ -5494,7 +5519,8 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
         u32 size = sizeof(*extent_item) + sizeof(*block_info) + sizeof(*iref);
 
         path = btrfs_alloc_path();
-        BUG_ON(!path);
+        if (!path)
+                return -ENOMEM;
 
         path->leave_spinning = 1;
         ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
@@ -5623,7 +5649,7 @@ struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
         if (!buf)
                 return ERR_PTR(-ENOMEM);
         btrfs_set_header_generation(buf, trans->transid);
-        btrfs_set_buffer_lockdep_class(buf, level);
+        btrfs_set_buffer_lockdep_class(root->root_key.objectid, buf, level);
         btrfs_tree_lock(buf);
         clean_tree_block(trans, root, buf);
 
@@ -5910,7 +5936,7 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
                         return 1;
 
                 if (path->locks[level] && !wc->keep_locks) {
-                        btrfs_tree_unlock(eb);
+                        btrfs_tree_unlock_rw(eb, path->locks[level]);
                         path->locks[level] = 0;
                 }
                 return 0;
@@ -5934,7 +5960,7 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
          * keep the tree lock
          */
         if (path->locks[level] && level > 0) {
-                btrfs_tree_unlock(eb);
+                btrfs_tree_unlock_rw(eb, path->locks[level]);
                 path->locks[level] = 0;
         }
         return 0;
@@ -6047,7 +6073,7 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
         BUG_ON(level != btrfs_header_level(next));
         path->nodes[level] = next;
         path->slots[level] = 0;
-        path->locks[level] = 1;
+        path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
         wc->level = level;
         if (wc->level == 1)
                 wc->reada_slot = 0;
@@ -6118,7 +6144,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
                         BUG_ON(level == 0);
                         btrfs_tree_lock(eb);
                         btrfs_set_lock_blocking(eb);
-                        path->locks[level] = 1;
+                        path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 
                         ret = btrfs_lookup_extent_info(trans, root,
                                                        eb->start, eb->len,
@@ -6127,8 +6153,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
                         BUG_ON(ret);
                         BUG_ON(wc->refs[level] == 0);
                         if (wc->refs[level] == 1) {
-                                btrfs_tree_unlock(eb);
-                                path->locks[level] = 0;
+                                btrfs_tree_unlock_rw(eb, path->locks[level]);
                                 return 1;
                         }
                 }
@@ -6150,7 +6175,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
                     btrfs_header_generation(eb) == trans->transid) {
                         btrfs_tree_lock(eb);
                         btrfs_set_lock_blocking(eb);
-                        path->locks[level] = 1;
+                        path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
                 }
                 clean_tree_block(trans, root, eb);
         }
@@ -6229,7 +6254,8 @@ static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
                                 return 0;
 
                         if (path->locks[level]) {
-                                btrfs_tree_unlock(path->nodes[level]);
+                                btrfs_tree_unlock_rw(path->nodes[level],
+                                                     path->locks[level]);
                                 path->locks[level] = 0;
                         }
                         free_extent_buffer(path->nodes[level]);
@@ -6251,8 +6277,8 @@ static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
  * also make sure backrefs for the shared block and all lower level
  * blocks are properly updated.
  */
-int btrfs_drop_snapshot(struct btrfs_root *root,
-                        struct btrfs_block_rsv *block_rsv, int update_ref)
+void btrfs_drop_snapshot(struct btrfs_root *root,
+                         struct btrfs_block_rsv *block_rsv, int update_ref)
 {
         struct btrfs_path *path;
         struct btrfs_trans_handle *trans;
@@ -6265,10 +6291,17 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
         int level;
 
         path = btrfs_alloc_path();
-        BUG_ON(!path);
+        if (!path) {
+                err = -ENOMEM;
+                goto out;
+        }
 
         wc = kzalloc(sizeof(*wc), GFP_NOFS);
-        BUG_ON(!wc);
+        if (!wc) {
+                btrfs_free_path(path);
+                err = -ENOMEM;
+                goto out;
+        }
 
         trans = btrfs_start_transaction(tree_root, 0);
         BUG_ON(IS_ERR(trans));
@@ -6281,7 +6314,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
                 path->nodes[level] = btrfs_lock_root_node(root);
                 btrfs_set_lock_blocking(path->nodes[level]);
                 path->slots[level] = 0;
-                path->locks[level] = 1;
+                path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
                 memset(&wc->update_progress, 0,
                        sizeof(wc->update_progress));
         } else {
@@ -6296,7 +6329,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
                 path->lowest_level = 0;
                 if (ret < 0) {
                         err = ret;
-                        goto out;
+                        goto out_free;
                 }
                 WARN_ON(ret > 0);
 
@@ -6403,11 +6436,14 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
                 free_extent_buffer(root->commit_root);
                 kfree(root);
         }
-out:
+out_free:
         btrfs_end_transaction_throttle(trans, tree_root);
         kfree(wc);
         btrfs_free_path(path);
-        return err;
+out:
+        if (err)
+                btrfs_std_error(root->fs_info, err);
+        return;
 }
 
 /*
@@ -6449,7 +6485,7 @@ int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
         level = btrfs_header_level(node);
         path->nodes[level] = node;
         path->slots[level] = 0;
-        path->locks[level] = 1;
+        path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 
         wc->refs[parent_level] = 1;
         wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;
@@ -6524,30 +6560,48 @@ static u64 update_block_group_flags(struct btrfs_root *root, u64 flags)
         return flags;
 }
 
-static int set_block_group_ro(struct btrfs_block_group_cache *cache)
+static int set_block_group_ro(struct btrfs_block_group_cache *cache, int force)
 {
         struct btrfs_space_info *sinfo = cache->space_info;
         u64 num_bytes;
+        u64 min_allocable_bytes;
         int ret = -ENOSPC;
 
-        if (cache->ro)
-                return 0;
+
+        /*
+         * We need some metadata space and system metadata space for
+         * allocating chunks in some corner cases until we force to set
+         * it to be readonly.
+         */
+        if ((sinfo->flags &
+             (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_METADATA)) &&
+            !force)
+                min_allocable_bytes = 1 * 1024 * 1024;
+        else
+                min_allocable_bytes = 0;
 
         spin_lock(&sinfo->lock);
         spin_lock(&cache->lock);
+
+        if (cache->ro) {
+                ret = 0;
+                goto out;
+        }
+
         num_bytes = cache->key.offset - cache->reserved - cache->pinned -
                     cache->bytes_super - btrfs_block_group_used(&cache->item);
 
         if (sinfo->bytes_used + sinfo->bytes_reserved + sinfo->bytes_pinned +
             sinfo->bytes_may_use + sinfo->bytes_readonly +
-            cache->reserved_pinned + num_bytes <= sinfo->total_bytes) {
+            cache->reserved_pinned + num_bytes + min_allocable_bytes <=
+            sinfo->total_bytes) {
                 sinfo->bytes_readonly += num_bytes;
                 sinfo->bytes_reserved += cache->reserved_pinned;
                 cache->reserved_pinned = 0;
                 cache->ro = 1;
                 ret = 0;
         }
-
+out:
         spin_unlock(&cache->lock);
         spin_unlock(&sinfo->lock);
         return ret;
@@ -6571,7 +6625,7 @@ int btrfs_set_block_group_ro(struct btrfs_root *root,
                 do_chunk_alloc(trans, root, 2 * 1024 * 1024, alloc_flags,
                                CHUNK_ALLOC_FORCE);
 
-        ret = set_block_group_ro(cache);
+        ret = set_block_group_ro(cache, 0);
         if (!ret)
                 goto out;
         alloc_flags = get_alloc_profile(root, cache->space_info->flags);
@@ -6579,7 +6633,7 @@ int btrfs_set_block_group_ro(struct btrfs_root *root,
                              CHUNK_ALLOC_FORCE);
         if (ret < 0)
                 goto out;
-        ret = set_block_group_ro(cache);
+        ret = set_block_group_ro(cache, 0);
 out:
         btrfs_end_transaction(trans, root);
         return ret;
@@ -6680,6 +6734,10 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
         struct btrfs_space_info *space_info;
         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
         struct btrfs_device *device;
+        u64 min_free;
+        u64 dev_min = 1;
+        u64 dev_nr = 0;
+        int index;
         int full = 0;
         int ret = 0;
 
@@ -6689,8 +6747,10 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
         if (!block_group)
                 return -1;
 
+        min_free = btrfs_block_group_used(&block_group->item);
+
         /* no bytes used, we're good */
-        if (!btrfs_block_group_used(&block_group->item))
+        if (!min_free)
                 goto out;
 
         space_info = block_group->space_info;
@@ -6706,10 +6766,9 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
          * all of the extents from this block group.  If we can, we're good
          */
         if ((space_info->total_bytes != block_group->key.offset) &&
-           (space_info->bytes_used + space_info->bytes_reserved +
-            space_info->bytes_pinned + space_info->bytes_readonly +
-            btrfs_block_group_used(&block_group->item) <
-            space_info->total_bytes)) {
+            (space_info->bytes_used + space_info->bytes_reserved +
+             space_info->bytes_pinned + space_info->bytes_readonly +
+             min_free < space_info->total_bytes)) {
                 spin_unlock(&space_info->lock);
                 goto out;
         }
@@ -6726,9 +6785,31 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
         if (full)
                 goto out;
 
+        /*
+         * index:
+         *      0: raid10
+         *      1: raid1
+         *      2: dup
+         *      3: raid0
+         *      4: single
+         */
+        index = get_block_group_index(block_group);
+        if (index == 0) {
+                dev_min = 4;
+                /* Divide by 2 */
+                min_free >>= 1;
+        } else if (index == 1) {
+                dev_min = 2;
+        } else if (index == 2) {
+                /* Multiply by 2 */
+                min_free <<= 1;
+        } else if (index == 3) {
+                dev_min = fs_devices->rw_devices;
+                do_div(min_free, dev_min);
+        }
+
         mutex_lock(&root->fs_info->chunk_mutex);
         list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
-                u64 min_free = btrfs_block_group_used(&block_group->item);
                 u64 dev_offset;
 
                 /*
@@ -6739,7 +6820,11 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
                         ret = find_free_dev_extent(NULL, device, min_free,
                                                    &dev_offset, NULL);
                         if (!ret)
+                                dev_nr++;
+
+                        if (dev_nr >= dev_min)
                                 break;
+
                         ret = -1;
                 }
         }
@@ -7016,7 +7101,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
 
                 set_avail_alloc_bits(root->fs_info, cache->flags);
                 if (btrfs_chunk_readonly(root, cache->key.objectid))
-                        set_block_group_ro(cache);
+                        set_block_group_ro(cache, 1);
         }
 
         list_for_each_entry_rcu(space_info, &root->fs_info->space_info, list) {
@@ -7030,9 +7115,9 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                  * mirrored block groups.
                  */
                 list_for_each_entry(cache, &space_info->block_groups[3], list)
-                        set_block_group_ro(cache);
+                        set_block_group_ro(cache, 1);
                 list_for_each_entry(cache, &space_info->block_groups[4], list)
-                        set_block_group_ro(cache);
+                        set_block_group_ro(cache, 1);
         }
 
         init_global_block_rsv(info);
@@ -7162,11 +7247,15 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
         spin_unlock(&cluster->refill_lock);
 
         path = btrfs_alloc_path();
-        BUG_ON(!path);
+        if (!path) {
+                ret = -ENOMEM;
+                goto out;
+        }
 
         inode = lookup_free_space_inode(root, block_group, path);
         if (!IS_ERR(inode)) {
-                btrfs_orphan_add(trans, inode);
+                ret = btrfs_orphan_add(trans, inode);
+                BUG_ON(ret);
                 clear_nlink(inode);
                 /* One for the block groups ref */
                 spin_lock(&block_group->lock);