btrfs: export the expected file extent through can_nocow_extent()

Currently function can_nocow_extent() only returns members needed for
extent_map.

However since we will soon change the extent_map structure to be more
like btrfs_file_extent_item, we want to expose the expected file extent
caused by the NOCOW write for future usage.

This introduces a new structure, btrfs_file_extent, to be a more
memory access friendly representation of btrfs_file_extent_item.
And use that structure to expose the expected file extent caused by the
NOCOW write.

For now there is no user of the new structure yet.

Reviewed-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Filipe Manana <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

1 files changed, 15 insertions, 1 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 21bd17d84f59..38de2fe23f43 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -514,9 +514,23 @@ int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
 			    u32 pgoff, u8 *csum, const u8 * const csum_expected);
 bool btrfs_data_csum_ok(struct btrfs_bio *bbio, struct btrfs_device *dev,
 			u32 bio_offset, struct bio_vec *bv);
+
+/*
+ * This represents details about the target file extent item of a write operation.
+ */
+struct btrfs_file_extent {
+	u64 disk_bytenr;
+	u64 disk_num_bytes;
+	u64 num_bytes;
+	u64 ram_bytes;
+	u64 offset;
+	u8 compression;
+};
+
 noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
 			      u64 *orig_start, u64 *orig_block_len,
-			      u64 *ram_bytes, bool nowait, bool strict);
+			      u64 *ram_bytes, struct btrfs_file_extent *file_extent,
+			      bool nowait, bool strict);
 
 void btrfs_del_delalloc_inode(struct btrfs_inode *inode);
 struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry);