1 files changed, 37 insertions, 34 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 380054c94e4b..fa7bbcab1a6a 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3417,6 +3417,9 @@ static long btrfs_fallocate(struct file *file, int mode,
 	u64 alloc_hint = 0;
 	u64 locked_end;
 	u64 actual_end = 0;
+	u64 data_space_needed = 0;
+	u64 data_space_reserved = 0;
+	u64 qgroup_reserved = 0;
 	struct extent_map *em;
 	int blocksize = btrfs_inode_sectorsize(BTRFS_I(inode));
 	int ret;
@@ -3437,18 +3440,6 @@ static long btrfs_fallocate(struct file *file, int mode,
 	if (mode & FALLOC_FL_PUNCH_HOLE)
 		return btrfs_punch_hole(file, offset, len);
 
-	/*
-	 * Only trigger disk allocation, don't trigger qgroup reserve
-	 *
-	 * For qgroup space, it will be checked later.
-	 */
-	if (!(mode & FALLOC_FL_ZERO_RANGE)) {
-		ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
-						      alloc_end - alloc_start);
-		if (ret < 0)
-			return ret;
-	}
-
 	btrfs_inode_lock(inode, BTRFS_ILOCK_MMAP);
 
 	if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) {
@@ -3548,48 +3539,64 @@ static long btrfs_fallocate(struct file *file, int mode,
 		if (em->block_start == EXTENT_MAP_HOLE ||
 		    (cur_offset >= inode->i_size &&
 		     !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
-			ret = add_falloc_range(&reserve_list, cur_offset,
-					       last_byte - cur_offset);
+			const u64 range_len = last_byte - cur_offset;
+
+			ret = add_falloc_range(&reserve_list, cur_offset, range_len);
 			if (ret < 0) {
 				free_extent_map(em);
 				break;
 			}
 			ret = btrfs_qgroup_reserve_data(BTRFS_I(inode),
-					&data_reserved, cur_offset,
-					last_byte - cur_offset);
+					&data_reserved, cur_offset, range_len);
 			if (ret < 0) {
-				cur_offset = last_byte;
 				free_extent_map(em);
 				break;
 			}
-		} else {
-			/*
-			 * Do not need to reserve unwritten extent for this
-			 * range, free reserved data space first, otherwise
-			 * it'll result in false ENOSPC error.
-			 */
-			btrfs_free_reserved_data_space(BTRFS_I(inode),
-				data_reserved, cur_offset,
-				last_byte - cur_offset);
+			qgroup_reserved += range_len;
+			data_space_needed += range_len;
 		}
 		free_extent_map(em);
 		cur_offset = last_byte;
 	}
 
+	if (!ret && data_space_needed > 0) {
+		/*
+		 * We are safe to reserve space here as we can't have delalloc
+		 * in the range, see above.
+		 */
+		ret = btrfs_alloc_data_chunk_ondemand(BTRFS_I(inode),
+						      data_space_needed);
+		if (!ret)
+			data_space_reserved = data_space_needed;
+	}
+
 	/*
 	 * If ret is still 0, means we're OK to fallocate.
 	 * Or just cleanup the list and exit.
 	 */
 	list_for_each_entry_safe(range, tmp, &reserve_list, list) {
-		if (!ret)
+		if (!ret) {
 			ret = btrfs_prealloc_file_range(inode, mode,
 					range->start,
 					range->len, i_blocksize(inode),
 					offset + len, &alloc_hint);
-		else
+			/*
+			 * btrfs_prealloc_file_range() releases space even
+			 * if it returns an error.
+			 */
+			data_space_reserved -= range->len;
+			qgroup_reserved -= range->len;
+		} else if (data_space_reserved > 0) {
 			btrfs_free_reserved_data_space(BTRFS_I(inode),
-					data_reserved, range->start,
-					range->len);
+					       data_reserved, range->start,
+					       range->len);
+			data_space_reserved -= range->len;
+			qgroup_reserved -= range->len;
+		} else if (qgroup_reserved > 0) {
+			btrfs_qgroup_free_data(BTRFS_I(inode), data_reserved,
+					       range->start, range->len);
+			qgroup_reserved -= range->len;
+		}
 		list_del(&range->list);
 		kfree(range);
 	}
@@ -3606,10 +3613,6 @@ out_unlock:
 			     &cached_state);
 out:
 	btrfs_inode_unlock(inode, BTRFS_ILOCK_MMAP);
-	/* Let go of our reservation. */
-	if (ret != 0 && !(mode & FALLOC_FL_ZERO_RANGE))
-		btrfs_free_reserved_data_space(BTRFS_I(inode), data_reserved,
-				cur_offset, alloc_end - cur_offset);
 	extent_changeset_free(data_reserved);
 	return ret;
 }