Btrfs: add a function to lookup a directory path by following backrefs
This will be used by the inode lookup ioctl.
Signed-off-by: TARUISI Hiroaki <taruishi.hiroak@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 645a179..ac2a28f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -48,6 +48,7 @@
#include "print-tree.h"
#include "volumes.h"
#include "locking.h"
+#include "ctree.h"
/* Mask out flags that are inappropriate for the given type of inode. */
static inline __u32 btrfs_mask_flags(umode_t mode, __u32 flags)
@@ -743,6 +744,97 @@
return ret;
}
+/*
+ Search INODE_REFs to identify path name of 'dirid' directory
+ in a 'tree_id' tree. and sets path name to 'name'.
+*/
+static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
+ u64 tree_id, u64 dirid, char *name)
+{
+ struct btrfs_root *root;
+ struct btrfs_key key;
+ char *name_stack, *ptr;
+ int ret = -1;
+ int slot;
+ int len;
+ int total_len = 0;
+ struct btrfs_inode_ref *iref;
+ struct extent_buffer *l;
+ struct btrfs_path *path;
+
+ if (dirid == BTRFS_FIRST_FREE_OBJECTID) {
+ name[0]='\0';
+ return 0;
+ }
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ name_stack = kzalloc(BTRFS_PATH_NAME_MAX+1, GFP_NOFS);
+ if (!name_stack) {
+ btrfs_free_path(path);
+ return -ENOMEM;
+ }
+
+ ptr = &name_stack[BTRFS_PATH_NAME_MAX];
+
+ key.objectid = tree_id;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+ root = btrfs_read_fs_root_no_name(info, &key);
+ if (IS_ERR(root)) {
+ printk(KERN_ERR "could not find root %llu\n", tree_id);
+ return -ENOENT;
+ }
+
+ key.objectid = dirid;
+ key.type = BTRFS_INODE_REF_KEY;
+ key.offset = 0;
+
+ while(1) {
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+
+ l = path->nodes[0];
+ slot = path->slots[0];
+ btrfs_item_key_to_cpu(l, &key, slot);
+
+ if (ret > 0 && (key.objectid != dirid ||
+ key.type != BTRFS_INODE_REF_KEY))
+ goto out;
+
+ iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);
+ len = btrfs_inode_ref_name_len(l, iref);
+ ptr -= len + 1;
+ total_len += len + 1;
+ if (ptr < name_stack)
+ goto out;
+
+ *(ptr + len) = '/';
+ read_extent_buffer(l, ptr,(unsigned long)(iref + 1), len);
+
+ if (key.offset == BTRFS_FIRST_FREE_OBJECTID)
+ break;
+
+ btrfs_release_path(root, path);
+ key.objectid = key.offset;
+ key.offset = 0;
+ dirid = key.objectid;
+
+ }
+ if (ptr < name_stack)
+ goto out;
+ strncpy(name, ptr, total_len);
+ name[total_len]='\0';
+ ret = 0;
+out:
+ btrfs_free_path(path);
+ kfree(name_stack);
+ return ret;
+}
+
static noinline int btrfs_ioctl_snap_destroy(struct file *file,
void __user *arg)
{