Btrfs-progs: delete bogus dir indexes

We may run across dir indexes that are corrupt in such a way that it makes them
useless, such as having a bad location key or a bad name.  In this case we can
just delete dir indexes that don't show up properly and then re-create what we
need.  When we delete dir indexes however we need to restart scanning the fs
tree as we could have greated bogus inode recs if the location key was bad, so
set it up so that if we had to delete an dir index we go ahead and free up our
inode recs and return -EAGAIN to check_fs_roots so it knows to restart the loop.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

1 files changed, 100 insertions, 0 deletions

diff --git a/dir-item.c b/dir-item.c
index 7b145ad1..a5bf8615 100644
--- a/dir-item.c
+++ b/dir-item.c
@@ -16,6 +16,7 @@
  * Boston, MA 021110-1307, USA.
  */
 
+#include <linux/limits.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "hash.h"
@@ -219,6 +220,97 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 	return btrfs_match_dir_item_name(root, path, name, name_len);
 }
 
+struct btrfs_dir_item *btrfs_lookup_dir_index(struct btrfs_trans_handle *trans,
+					      struct btrfs_root *root,
+					      struct btrfs_path *path, u64 dir,
+					      const char *name, int name_len,
+					      u64 index, int mod)
+{
+	int ret;
+	struct btrfs_key key;
+	int ins_len = mod < 0 ? -1 : 0;
+	int cow = mod != 0;
+
+	key.objectid = dir;
+	key.type = BTRFS_DIR_INDEX_KEY;
+	key.offset = index;
+
+	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
+	if (ret < 0)
+		return ERR_PTR(ret);
+	if (ret > 0)
+		return ERR_PTR(-ENOENT);
+
+	return btrfs_match_dir_item_name(root, path, name, name_len);
+}
+
+/*
+ * given a pointer into a directory item, delete it.  This
+ * handles items that have more than one entry in them.
+ */
+int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root,
+			      struct btrfs_path *path,
+			      struct btrfs_dir_item *di)
+{
+
+	struct extent_buffer *leaf;
+	u32 sub_item_len;
+	u32 item_len;
+	int ret = 0;
+
+	leaf = path->nodes[0];
+	sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
+		btrfs_dir_data_len(leaf, di);
+	item_len = btrfs_item_size_nr(leaf, path->slots[0]);
+	if (sub_item_len == item_len) {
+		ret = btrfs_del_item(trans, root, path);
+	} else {
+		unsigned long ptr = (unsigned long)di;
+		unsigned long start;
+
+		start = btrfs_item_ptr_offset(leaf, path->slots[0]);
+		memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
+			item_len - (ptr + sub_item_len - start));
+		btrfs_truncate_item(trans, root, path, item_len - sub_item_len, 1);
+	}
+	return ret;
+}
+
+int verify_dir_item(struct btrfs_root *root,
+		    struct extent_buffer *leaf,
+		    struct btrfs_dir_item *dir_item)
+{
+	u16 namelen = BTRFS_NAME_LEN;
+	u8 type = btrfs_dir_type(leaf, dir_item);
+
+	if (type >= BTRFS_FT_MAX) {
+		fprintf(stderr, "invalid dir item type: %d",
+		       (int)type);
+		return 1;
+	}
+
+	if (type == BTRFS_FT_XATTR)
+		namelen = XATTR_NAME_MAX;
+
+	if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
+		fprintf(stderr, "invalid dir item name len: %u",
+		       (unsigned)btrfs_dir_data_len(leaf, dir_item));
+		return 1;
+	}
+
+	/* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
+	if ((btrfs_dir_data_len(leaf, dir_item) +
+	     btrfs_dir_name_len(leaf, dir_item)) > BTRFS_MAX_XATTR_SIZE(root)) {
+		fprintf(stderr, "invalid dir item name + data len: %u + %u",
+		       (unsigned)btrfs_dir_name_len(leaf, dir_item),
+		       (unsigned)btrfs_dir_data_len(leaf, dir_item));
+		return 1;
+	}
+
+	return 0;
+}
+
 static struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 			      struct btrfs_path *path,
 			      const char *name, int name_len)
@@ -233,10 +325,18 @@ static struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
 	leaf = path->nodes[0];
 	dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
 	total_len = btrfs_item_size_nr(leaf, path->slots[0]);
+	if (verify_dir_item(root, leaf, dir_item))
+		return NULL;
+
 	while(cur < total_len) {
 		this_len = sizeof(*dir_item) +
 			btrfs_dir_name_len(leaf, dir_item) +
 			btrfs_dir_data_len(leaf, dir_item);
+		if (this_len > (total_len - cur)) {
+			fprintf(stderr, "invalid dir item size\n");
+			return NULL;
+		}
+
 		name_ptr = (unsigned long)(dir_item + 1);
 
 		if (btrfs_dir_name_len(leaf, dir_item) == name_len &&