1 files changed, 51 insertions, 0 deletions
diff --git a/extent_io.c b/extent_io.c
index 78deb502..5093aeb2 100644
--- a/extent_io.c
+++ b/extent_io.c
@@ -27,6 +27,8 @@
 #include "kerncompat.h"
 #include "extent_io.h"
 #include "list.h"
+#include "ctree.h"
+#include "volumes.h"
 
 u64 cache_soft_max = 1024 * 1024 * 256;
 u64 cache_hard_max = 1 * 1024 * 1024 * 1024;
@@ -696,6 +698,55 @@ out:
 	return ret;
 }
 
+int read_data_from_disk(struct btrfs_fs_info *info, void *buf, u64 offset,
+			u64 bytes, int mirror)
+{
+	struct btrfs_multi_bio *multi = NULL;
+	struct btrfs_device *device;
+	u64 bytes_left = bytes;
+	u64 read_len;
+	u64 total_read = 0;
+	int ret;
+
+	while (bytes_left) {
+		read_len = bytes_left;
+		ret = btrfs_map_block(&info->mapping_tree, READ, offset,
+				      &read_len, &multi, mirror, NULL);
+		if (ret) {
+			fprintf(stderr, "Couldn't map the block %Lu\n",
+				offset);
+			return -EIO;
+		}
+		device = multi->stripes[0].dev;
+
+		read_len = min(bytes_left, read_len);
+		if (device->fd == 0) {
+			kfree(multi);
+			return -EIO;
+		}
+
+		ret = pread(device->fd, buf + total_read, read_len,
+			    multi->stripes[0].physical);
+		kfree(multi);
+		if (ret < 0) {
+			fprintf(stderr, "Error reading %Lu, %d\n", offset,
+				ret);
+			return ret;
+		}
+		if (ret != read_len) {
+			fprintf(stderr, "Short read for %Lu, read %d, "
+				"read_len %Lu\n", offset, ret, read_len);
+			return -EIO;
+		}
+
+		bytes_left -= read_len;
+		offset += read_len;
+		total_read += read_len;
+	}
+
+	return 0;
+}
+
 int set_extent_buffer_uptodate(struct extent_buffer *eb)
 {
 	eb->flags |= EXTENT_UPTODATE;