Btrfs: add and improve comments
This improves the comments at the top of many functions. It didn't
dive into the guts of functions because I was trying to
avoid merging problems with the new allocator and back reference work.
extent-tree.c and volumes.c were both skipped, and there is definitely
more work todo in cleaning and commenting the code.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 0091c01..eb7f765 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -22,8 +22,10 @@
#include "print-tree.h"
/*
- * returns 0 on finding something, 1 if no more roots are there
- * and < 0 on error
+ * search forward for a root, starting with objectid 'search_start'
+ * if a root key is found, the objectid we find is filled into 'found_objectid'
+ * and 0 is returned. < 0 is returned on error, 1 if there is nothing
+ * left in the tree.
*/
int btrfs_search_root(struct btrfs_root *root, u64 search_start,
u64 *found_objectid)
@@ -66,6 +68,11 @@
return ret;
}
+/*
+ * lookup the root with the highest offset for a given objectid. The key we do
+ * find is copied into 'key'. If we find something return 0, otherwise 1, < 0
+ * on error.
+ */
int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
struct btrfs_root_item *item, struct btrfs_key *key)
{
@@ -104,6 +111,9 @@
return ret;
}
+/*
+ * copy the data in 'item' into the btree
+ */
int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_key *key, struct btrfs_root_item
*item)
@@ -147,6 +157,12 @@
return ret;
}
+/*
+ * at mount time we want to find all the old transaction snapshots that were in
+ * the process of being deleted if we crashed. This is any root item with an offset
+ * lower than the latest root. They need to be queued for deletion to finish
+ * what was happening when we crashed.
+ */
int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,
struct btrfs_root *latest)
{
@@ -227,6 +243,7 @@
return ret;
}
+/* drop the root item for 'key' from 'root' */
int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct btrfs_key *key)
{