btrfs: qgroup: do a reservation in a higher level.

There are two problems in qgroup:

a). The PAGE_CACHE is 4K, even when we are writing a data of 1K,
qgroup will reserve a 4K size. It will cause the last 3K in a qgroup
is not available to user.

b). When user is writing a inline data, qgroup will not reserve it,
it means this is a window we can exceed the limit of a qgroup.

The main idea of this patch is reserving the data size of write_bytes
rather than the reserve_bytes. It means qgroup will not care about
the data size btrfs will reserve for user, but only care about the
data size user is going to write. Then reserve it when user want to
write and release it in transaction committed.

In this way, qgroup can be released from the complex procedure in
btrfs and only do the reserve when user want to write and account
when the data is written in commit_transaction().

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 6 insertions, 32 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4d3774605a85..1eef4ee01d1a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3331,7 +3331,7 @@ again:
 	num_pages *= 16;
 	num_pages *= PAGE_CACHE_SIZE;
 
-	ret = btrfs_check_data_free_space(inode, num_pages);
+	ret = btrfs_check_data_free_space(inode, num_pages, num_pages);
 	if (ret)
 		goto out_put;
 
@@ -3851,7 +3851,7 @@ u64 btrfs_get_alloc_profile(struct btrfs_root *root, int data)
  * This will check the space that the inode allocates from to make sure we have
  * enough space for bytes.
  */
-int btrfs_check_data_free_space(struct inode *inode, u64 bytes)
+int btrfs_check_data_free_space(struct inode *inode, u64 bytes, u64 write_bytes)
 {
 	struct btrfs_space_info *data_sinfo;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -3969,7 +3969,7 @@ commit_trans:
 					      data_sinfo->flags, bytes, 1);
 		return -ENOSPC;
 	}
-	ret = btrfs_qgroup_reserve(root, bytes);
+	ret = btrfs_qgroup_reserve(root, write_bytes);
 	if (ret)
 		goto out;
 	data_sinfo->bytes_may_use += bytes;
@@ -3995,7 +3995,6 @@ void btrfs_free_reserved_data_space(struct inode *inode, u64 bytes)
 	data_sinfo = root->fs_info->data_sinfo;
 	spin_lock(&data_sinfo->lock);
 	WARN_ON(data_sinfo->bytes_may_use < bytes);
-	btrfs_qgroup_free(root, bytes);
 	data_sinfo->bytes_may_use -= bytes;
 	trace_btrfs_space_reservation(root->fs_info, "space_info",
 				      data_sinfo->flags, bytes, 0);
@@ -5243,8 +5242,6 @@ void btrfs_subvolume_release_metadata(struct btrfs_root *root,
 				      u64 qgroup_reserved)
 {
 	btrfs_block_rsv_release(root, rsv, (u64)-1);
-	if (qgroup_reserved)
-		btrfs_qgroup_free(root, qgroup_reserved);
 }
 
 /**
@@ -5478,11 +5475,8 @@ out_fail:
 			to_free = 0;
 	}
 	spin_unlock(&BTRFS_I(inode)->lock);
-	if (dropped) {
-		if (root->fs_info->quota_enabled)
-			btrfs_qgroup_free(root, dropped * root->nodesize);
+	if (dropped)
 		to_free += btrfs_calc_trans_metadata_size(root, dropped);
-	}
 
 	if (to_free) {
 		btrfs_block_rsv_release(root, block_rsv, to_free);
@@ -5524,9 +5518,6 @@ void btrfs_delalloc_release_metadata(struct inode *inode, u64 num_bytes)
 
 	trace_btrfs_space_reservation(root->fs_info, "delalloc",
 				      btrfs_ino(inode), to_free, 0);
-	if (root->fs_info->quota_enabled) {
-		btrfs_qgroup_free(root, dropped * root->nodesize);
-	}
 
 	btrfs_block_rsv_release(root, &root->fs_info->delalloc_block_rsv,
 				to_free);
@@ -5551,7 +5542,7 @@ int btrfs_delalloc_reserve_space(struct inode *inode, u64 num_bytes)
 {
 	int ret;
 
-	ret = btrfs_check_data_free_space(inode, num_bytes);
+	ret = btrfs_check_data_free_space(inode, num_bytes, num_bytes);
 	if (ret)
 		return ret;
 
@@ -5727,12 +5718,8 @@ static int pin_down_extent(struct btrfs_root *root,
 
 	set_extent_dirty(root->fs_info->pinned_extents, bytenr,
 			 bytenr + num_bytes - 1, GFP_NOFS | __GFP_NOFAIL);
-	if (reserved) {
-		btrfs_qgroup_update_reserved_bytes(root->fs_info,
-						   root->root_key.objectid,
-						   num_bytes, -1);
+	if (reserved)
 		trace_btrfs_reserved_extent_free(root, bytenr, num_bytes);
-	}
 	return 0;
 }
 
@@ -6470,9 +6457,6 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
 		btrfs_put_block_group(cache);
 		trace_btrfs_reserved_extent_free(root, buf->start, buf->len);
 		pin = 0;
-		btrfs_qgroup_update_reserved_bytes(root->fs_info,
-						   root->root_key.objectid,
-						   buf->len, -1);
 	}
 out:
 	if (pin)
@@ -7205,9 +7189,6 @@ static int __btrfs_free_reserved_extent(struct btrfs_root *root,
 			ret = btrfs_discard_extent(root, start, len, NULL);
 		btrfs_add_free_space(cache, start, len);
 		btrfs_update_reserved_bytes(cache, len, RESERVE_FREE, delalloc);
-		btrfs_qgroup_update_reserved_bytes(root->fs_info,
-						   root->root_key.objectid,
-						   len, -1);
 	}
 
 	btrfs_put_block_group(cache);
@@ -7446,9 +7427,6 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
 	BUG_ON(ret); /* logic error */
 	ret = alloc_reserved_file_extent(trans, root, 0, root_objectid,
 					 0, owner, offset, ins, 1);
-	btrfs_qgroup_update_reserved_bytes(root->fs_info,
-					   root->root_key.objectid,
-					   ins->offset, 1);
 	btrfs_put_block_group(block_group);
 	return ret;
 }
@@ -7595,10 +7573,6 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
 		return ERR_PTR(ret);
 	}
 
-	btrfs_qgroup_update_reserved_bytes(root->fs_info,
-					   root_objectid,
-					   ins.offset, 1);
-
 	buf = btrfs_init_new_buffer(trans, root, ins.objectid, level);
 	BUG_ON(IS_ERR(buf)); /* -ENOMEM */