1 files changed, 129 insertions, 109 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index aca3314..180a501 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3078,38 +3078,6 @@ out:
 	return ret;
 }
 
-static int maybe_allocate_chunk(struct btrfs_trans_handle *trans,
-				struct btrfs_root *root,
-				struct btrfs_space_info *sinfo, u64 num_bytes)
-{
-	int ret;
-	int end_trans = 0;
-
-	if (sinfo->full)
-		return 0;
-
-	spin_lock(&sinfo->lock);
-	ret = should_alloc_chunk(sinfo, num_bytes + 2 * 1024 * 1024);
-	spin_unlock(&sinfo->lock);
-	if (!ret)
-		return 0;
-
-	if (!trans) {
-		trans = btrfs_join_transaction(root, 1);
-		BUG_ON(IS_ERR(trans));
-		end_trans = 1;
-	}
-
-	ret = do_chunk_alloc(trans, root->fs_info->extent_root,
-			     num_bytes + 2 * 1024 * 1024,
-			     get_alloc_profile(root, sinfo->flags), 0);
-
-	if (end_trans)
-		btrfs_end_transaction(trans, root);
-
-	return ret == 1 ? 1 : 0;
-}
-
 /*
  * shrink metadata reservation for delalloc
  */
@@ -3167,79 +3135,138 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
 	return reclaimed >= to_reclaim;
 }
 
-static int should_retry_reserve(struct btrfs_trans_handle *trans,
-				struct btrfs_root *root,
-				struct btrfs_block_rsv *block_rsv,
-				u64 num_bytes, int *retries)
+/*
+ * Retries tells us how many times we've called reserve_metadata_bytes.  The
+ * idea is if this is the first call (retries == 0) then we will add to our
+ * reserved count if we can't make the allocation in order to hold our place
+ * while we go and try and free up space.  That way for retries > 1 we don't try
+ * and add space, we just check to see if the amount of unused space is >= the
+ * total space, meaning that our reservation is valid.
+ *
+ * However if we don't intend to retry this reservation, pass -1 as retries so
+ * that it short circuits this logic.
+ */
+static int reserve_metadata_bytes(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root,
+				  struct btrfs_block_rsv *block_rsv,
+				  u64 orig_bytes, int flush)
 {
 	struct btrfs_space_info *space_info = block_rsv->space_info;
-	int ret;
+	u64 unused;
+	u64 num_bytes = orig_bytes;
+	int retries = 0;
+	int ret = 0;
+	bool reserved = false;
 
-	if ((*retries) > 2)
-		return -ENOSPC;
+again:
+	ret = -ENOSPC;
+	if (reserved)
+		num_bytes = 0;
 
-	ret = maybe_allocate_chunk(trans, root, space_info, num_bytes);
-	if (ret)
-		return 1;
+	spin_lock(&space_info->lock);
+	unused = space_info->bytes_used + space_info->bytes_reserved +
+		 space_info->bytes_pinned + space_info->bytes_readonly +
+		 space_info->bytes_may_use;
 
-	if (trans && trans->transaction->in_commit)
-		return -ENOSPC;
+	/*
+	 * The idea here is that we've not already over-reserved the block group
+	 * then we can go ahead and save our reservation first and then start
+	 * flushing if we need to.  Otherwise if we've already overcommitted
+	 * lets start flushing stuff first and then come back and try to make
+	 * our reservation.
+	 */
+	if (unused <= space_info->total_bytes) {
+		unused -= space_info->total_bytes;
+		if (unused >= num_bytes) {
+			if (!reserved)
+				space_info->bytes_reserved += orig_bytes;
+			ret = 0;
+		} else {
+			/*
+			 * Ok set num_bytes to orig_bytes since we aren't
+			 * overocmmitted, this way we only try and reclaim what
+			 * we need.
+			 */
+			num_bytes = orig_bytes;
+		}
+	} else {
+		/*
+		 * Ok we're over committed, set num_bytes to the overcommitted
+		 * amount plus the amount of bytes that we need for this
+		 * reservation.
+		 */
+		num_bytes = unused - space_info->total_bytes +
+			(orig_bytes * (retries + 1));
+	}
 
-	ret = shrink_delalloc(trans, root, num_bytes, 0);
-	if (ret)
-		return ret;
+	/*
+	 * Couldn't make our reservation, save our place so while we're trying
+	 * 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;
+	}
 
-	spin_lock(&space_info->lock);
-	if (space_info->bytes_pinned < num_bytes)
-		ret = 1;
 	spin_unlock(&space_info->lock);
-	if (ret)
-		return -ENOSPC;
-
-	(*retries)++;
 
-	if (trans)
-		return -EAGAIN;
+	if (!ret)
+		return 0;
 
-	trans = btrfs_join_transaction(root, 1);
-	BUG_ON(IS_ERR(trans));
-	ret = btrfs_commit_transaction(trans, root);
-	BUG_ON(ret);
+	if (!flush)
+		goto out;
 
-	return 1;
-}
+	/*
+	 * We do synchronous shrinking since we don't actually unreserve
+	 * metadata until after the IO is completed.
+	 */
+	ret = shrink_delalloc(trans, root, num_bytes, 1);
+	if (ret > 0)
+		return 0;
+	else if (ret < 0)
+		goto out;
 
-static int reserve_metadata_bytes(struct btrfs_block_rsv *block_rsv,
-				  u64 num_bytes)
-{
-	struct btrfs_space_info *space_info = block_rsv->space_info;
-	u64 unused;
-	int ret = -ENOSPC;
+	/*
+	 * 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,
+	 * so go back around and try again.
+	 */
+	if (retries < 2) {
+		retries++;
+		goto again;
+	}
 
 	spin_lock(&space_info->lock);
-	unused = space_info->bytes_used + space_info->bytes_reserved +
-		 space_info->bytes_pinned + space_info->bytes_readonly +
-		 space_info->bytes_may_use;
+	/*
+	 * Not enough space to be reclaimed, don't bother committing the
+	 * transaction.
+	 */
+	if (space_info->bytes_pinned < orig_bytes)
+		ret = -ENOSPC;
+	spin_unlock(&space_info->lock);
+	if (ret)
+		goto out;
 
-	if (unused < space_info->total_bytes)
-		unused = space_info->total_bytes - unused;
-	else
-		unused = 0;
+	ret = -EAGAIN;
+	if (trans)
+		goto out;
 
-	if (unused >= num_bytes) {
-		if (block_rsv->priority >= 10) {
-			space_info->bytes_reserved += num_bytes;
-			ret = 0;
-		} else {
-			if ((unused + block_rsv->reserved) *
-			    block_rsv->priority >=
-			    (num_bytes + block_rsv->reserved) * 10) {
-				space_info->bytes_reserved += num_bytes;
-				ret = 0;
-			}
-		}
+
+	ret = -ENOSPC;
+	trans = btrfs_join_transaction(root, 1);
+	if (IS_ERR(trans))
+		goto out;
+	ret = btrfs_commit_transaction(trans, root);
+	if (!ret)
+		goto again;
+
+out:
+	if (reserved) {
+		spin_lock(&space_info->lock);
+		space_info->bytes_reserved -= orig_bytes;
+		spin_unlock(&space_info->lock);
 	}
-	spin_unlock(&space_info->lock);
 
 	return ret;
 }
@@ -3383,23 +3410,19 @@ void btrfs_add_durable_block_rsv(struct btrfs_fs_info *fs_info,
 int btrfs_block_rsv_add(struct btrfs_trans_handle *trans,
 			struct btrfs_root *root,
 			struct btrfs_block_rsv *block_rsv,
-			u64 num_bytes, int *retries)
+			u64 num_bytes)
 {
 	int ret;
 
 	if (num_bytes == 0)
 		return 0;
-again:
-	ret = reserve_metadata_bytes(block_rsv, num_bytes);
+
+	ret = reserve_metadata_bytes(trans, root, block_rsv, num_bytes, 1);
 	if (!ret) {
 		block_rsv_add_bytes(block_rsv, num_bytes, 1);
 		return 0;
 	}
 
-	ret = should_retry_reserve(trans, root, block_rsv, num_bytes, retries);
-	if (ret > 0)
-		goto again;
-
 	return ret;
 }
 
@@ -3434,7 +3457,8 @@ int btrfs_block_rsv_check(struct btrfs_trans_handle *trans,
 		return 0;
 
 	if (block_rsv->refill_used) {
-		ret = reserve_metadata_bytes(block_rsv, num_bytes);
+		ret = reserve_metadata_bytes(trans, root, block_rsv,
+					     num_bytes, 0);
 		if (!ret) {
 			block_rsv_add_bytes(block_rsv, num_bytes, 0);
 			return 0;
@@ -3614,7 +3638,7 @@ static u64 calc_trans_metadata_size(struct btrfs_root *root, int num_items)
 
 int btrfs_trans_reserve_metadata(struct btrfs_trans_handle *trans,
 				 struct btrfs_root *root,
-				 int num_items, int *retries)
+				 int num_items)
 {
 	u64 num_bytes;
 	int ret;
@@ -3624,7 +3648,7 @@ int btrfs_trans_reserve_metadata(struct btrfs_trans_handle *trans,
 
 	num_bytes = calc_trans_metadata_size(root, num_items);
 	ret = btrfs_block_rsv_add(trans, root, &root->fs_info->trans_block_rsv,
-				  num_bytes, retries);
+				  num_bytes);
 	if (!ret) {
 		trans->bytes_reserved += num_bytes;
 		trans->block_rsv = &root->fs_info->trans_block_rsv;
@@ -3698,14 +3722,13 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes)
 	struct btrfs_block_rsv *block_rsv = &root->fs_info->delalloc_block_rsv;
 	u64 to_reserve;
 	int nr_extents;
-	int retries = 0;
 	int ret;
 
 	if (btrfs_transaction_in_commit(root->fs_info))
 		schedule_timeout(1);
 
 	num_bytes = ALIGN(num_bytes, root->sectorsize);
-again:
+
 	spin_lock(&BTRFS_I(inode)->accounting_lock);
 	nr_extents = atomic_read(&BTRFS_I(inode)->outstanding_extents) + 1;
 	if (nr_extents > BTRFS_I(inode)->reserved_extents) {
@@ -3715,18 +3738,14 @@ again:
 		nr_extents = 0;
 		to_reserve = 0;
 	}
+	spin_unlock(&BTRFS_I(inode)->accounting_lock);
 
 	to_reserve += calc_csum_metadata_size(inode, num_bytes);
-	ret = reserve_metadata_bytes(block_rsv, to_reserve);
-	if (ret) {
-		spin_unlock(&BTRFS_I(inode)->accounting_lock);
-		ret = should_retry_reserve(NULL, root, block_rsv, to_reserve,
-					   &retries);
-		if (ret > 0)
-			goto again;
+	ret = reserve_metadata_bytes(NULL, root, block_rsv, to_reserve, 1);
+	if (ret)
 		return ret;
-	}
 
+	spin_lock(&BTRFS_I(inode)->accounting_lock);
 	BTRFS_I(inode)->reserved_extents += nr_extents;
 	atomic_inc(&BTRFS_I(inode)->outstanding_extents);
 	spin_unlock(&BTRFS_I(inode)->accounting_lock);
@@ -5325,7 +5344,8 @@ use_block_rsv(struct btrfs_trans_handle *trans,
 	block_rsv = get_block_rsv(trans, root);
 
 	if (block_rsv->size == 0) {
-		ret = reserve_metadata_bytes(block_rsv, blocksize);
+		ret = reserve_metadata_bytes(trans, root, block_rsv,
+					     blocksize, 0);
 		if (ret)
 			return ERR_PTR(ret);
 		return block_rsv;