btrfs: send: in case of IO error log it

Currently if we get IO error while doing send then we abort without
logging information about which file caused issue.  So log it to help
with debugging.

CC: [email protected] # 4.9+
Signed-off-by: Dāvis Mosāns <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: davispuh

fs/btrfs/send.c

@@ -4999,6 +4999,10 @@ static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
 			lock_page(page);
 			if (!PageUptodate(page)) {
 				unlock_page(page);
+				btrfs_err(fs_info,
+			"send: IO error at offset %llu for inode %llu root %llu",
+					page_offset(page), sctx->cur_ino,
+					sctx->send_root->root_key.objectid);
 				put_page(page);
 				ret = -EIO;
 				break;