fs: btrfs: Introduce btrfs_read_extent_inline() and btrfs_read_extent_reg()

These two functions are used to do sector aligned read, which will be
later used to implement btrfs_file_read().

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>

1 files changed, 36 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4d08b0204a..4da1b80038 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -565,6 +565,42 @@ struct extent_buffer* read_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr,
 	return ERR_PTR(ret);
 }
 
+int read_extent_data(struct btrfs_fs_info *fs_info, char *data, u64 logical,
+		     u64 *len, int mirror)
+{
+	u64 offset = 0;
+	struct btrfs_multi_bio *multi = NULL;
+	struct btrfs_device *device;
+	int ret = 0;
+	u64 max_len = *len;
+
+	ret = btrfs_map_block(fs_info, READ, logical, len, &multi, mirror,
+			      NULL);
+	if (ret) {
+		fprintf(stderr, "Couldn't map the block %llu\n",
+				logical + offset);
+		goto err;
+	}
+	device = multi->stripes[0].dev;
+
+	if (*len > max_len)
+		*len = max_len;
+	if (!device->desc || !device->part) {
+		ret = -EIO;
+		goto err;
+	}
+
+	ret = __btrfs_devread(device->desc, device->part, data, *len,
+			      multi->stripes[0].physical);
+	if (ret != *len)
+		ret = -EIO;
+	else
+		ret = 0;
+err:
+	kfree(multi);
+	return ret;
+}
+
 void btrfs_setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
 		      u64 objectid)
 {