[PATCH U-BOOT 23/26] fs: btrfs: Introduce lookup_data_extent() for later use

Qu Wenruo
2020-04-22T06:50:06Z

fs/btrfs/inode.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 101 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 986b9347b012..3332055ff840 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -814,3 +814,104 @@ out:
free(dbuf);
return ret;
}
+
+/*
+ * Get the first file extent that covers bytenr @file_offset.
+ *
+ * @file_offset must be aligned to sectorsize.
+ *
+ * return 0 for found, and path points to the file extent.
+ * return >0 for not found, and fill @next_offset.
+ * @next_offset can be 0 if there is no next file extent.
+ * return <0 for error.
+ */
+static int lookup_data_extent(struct btrfs_root *root, struct btrfs_path *path,
+ u64 ino, u64 file_offset, u64 *next_offset)
+{
+ struct btrfs_key key;
+ struct btrfs_file_extent_item *fi;
+ u8 extent_type;
+ int ret = 0;
+
+ ASSERT(IS_ALIGNED(file_offset, root->fs_info->sectorsize));
+ key.objectid = ino;
+ key.type = BTRFS_EXTENT_DATA_KEY;
+ key.offset = file_offset;
+
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ /* Error or we're already at the file extent */
+ if (ret <= 0)
+ return ret;
+ if (ret > 0) {
+ /* Check previous file extent */
+ ret = btrfs_previous_item(root, path, ino,
+ BTRFS_EXTENT_DATA_KEY);
+ if (ret < 0)
+ return ret;
+ if (ret > 0)
+ goto check_next;
+ }
+ /* Now the key.offset must be smaller than @file_offset */
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+ if (key.objectid != ino ||
+ key.type != BTRFS_EXTENT_DATA_KEY)
+ goto check_next;
+
+ fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
+ struct btrfs_file_extent_item);
+ extent_type = btrfs_file_extent_type(path->nodes[0], fi);
+ if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+ if (file_offset == 0)
+ return 0;
+ /* Inline extent should be the only extent, no next extent. */
+ *next_offset = 0;
+ return 1;
+ }
+
+ /* This file extent covers @file_offset */
+ if (key.offset <= file_offset && key.offset +
+ btrfs_file_extent_num_bytes(path->nodes[0], fi) > file_offset)
+ return 0;
+check_next:
+ ret = btrfs_next_item(root, path);
+ if (ret < 0)
+ return ret;
+ if (ret > 0) {
+ *next_offset = 0;
+ return 1;
+ }
+
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+ fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
+ struct btrfs_file_extent_item);
+ /* Next next data extent */
+ if (key.objectid != ino ||
+ key.type != BTRFS_EXTENT_DATA_KEY) {
+ *next_offset = 0;
+ return 1;
+ }
+ /* Current file extent already beyond @file_offset */
+ if (key.offset > file_offset) {
+ *next_offset = key.offset;
+ return 1;
+ }
+ /* This file extent covers @file_offset */
+ if (key.offset <= file_offset && key.offset +
+ btrfs_file_extent_num_bytes(path->nodes[0], fi) > file_offset)
+ return 0;
+ /* This file extent ends before @file_offset, check next */
+ ret = btrfs_next_item(root, path);
+ if (ret < 0)
+ return ret;
+ if (ret > 0) {
+ *next_offset = 0;
+ return 1;
+ }
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+ if (key.type != BTRFS_EXTENT_DATA_KEY || key.objectid != ino) {
+ *next_offset = 0;
+ return 1;
+ }
+ *next_offset = key.offset;
+ return 1;
+}
--
2.26.0