btrfs-progs: make fsck deal with bogus items

We can deal with corrupt items by deleting them in a few cases.  Fsck can easily
recover from a missing extent item or a dir index item.  So if we notice a item
is completely bogus and it is of a key that we know we can repair then just
delete it and carry on.  Thanks,

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

diff --git a/cmds-check.c b/cmds-check.c
index db7f745..acdf312 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -2834,6 +2834,42 @@ static int fix_key_order(struct btrfs_trans_handle *trans,
        return ret;
 }
 
+static int delete_bogus_item(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root,
+                            struct btrfs_path *path,
+                            struct extent_buffer *buf, int slot)
+{
+       struct btrfs_key key;
+       int nritems = btrfs_header_nritems(buf);
+
+       btrfs_item_key_to_cpu(buf, &key, slot);
+
+       /* These are all the keys we can deal with missing. */
+       if (key.type != BTRFS_DIR_INDEX_KEY &&
+           key.type != BTRFS_EXTENT_ITEM_KEY &&
+           key.type != BTRFS_METADATA_ITEM_KEY &&
+           key.type != BTRFS_TREE_BLOCK_REF_KEY &&
+           key.type != BTRFS_EXTENT_DATA_REF_KEY)
+               return -1;
+
+       printf("Deleting bogus item [%llu,%u,%llu] at slot %d on block %llu\n",
+              (unsigned long long)key.objectid, key.type,
+              (unsigned long long)key.offset, slot, buf->start);
+       memmove_extent_buffer(buf, btrfs_item_nr_offset(slot),
+                             btrfs_item_nr_offset(slot + 1),
+                             sizeof(struct btrfs_item) *
+                             (nritems - slot - 1));
+       btrfs_set_header_nritems(buf, nritems - 1);
+       if (slot == 0) {
+               struct btrfs_disk_key disk_key;
+
+               btrfs_item_key(buf, &disk_key, 0);
+               btrfs_fixup_low_keys(root, path, &disk_key, 1);
+       }
+       btrfs_mark_buffer_dirty(buf);
+       return 0;
+}
+
 static int fix_item_offset(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           struct extent_buffer *buf)
@@ -2873,6 +2909,7 @@ static int fix_item_offset(struct btrfs_trans_handle *trans,
        }
 
        buf = path->nodes[level];
+again:
        for (i = 0; i < btrfs_header_nritems(buf); i++) {
                unsigned int shift = 0, offset;
 
@@ -2880,6 +2917,10 @@ static int fix_item_offset(struct btrfs_trans_handle *trans,
                    BTRFS_LEAF_DATA_SIZE(root)) {
                        if (btrfs_item_end_nr(buf, i) >
                            BTRFS_LEAF_DATA_SIZE(root)) {
+                               ret = delete_bogus_item(trans, root, path,
+                                                       buf, i);
+                               if (!ret)
+                                       goto again;
                                fprintf(stderr, "item is off the end of the "
                                        "leaf, can't fix\n");
                                ret = -EIO;
@@ -2891,6 +2932,10 @@ static int fix_item_offset(struct btrfs_trans_handle *trans,
                           btrfs_item_offset_nr(buf, i - 1)) {
                        if (btrfs_item_end_nr(buf, i) >
                            btrfs_item_offset_nr(buf, i - 1)) {
+                               ret = delete_bogus_item(trans, root, path,
+                                                       buf, i);
+                               if (!ret)
+                                       goto again;
                                fprintf(stderr, "items overlap, can't fix\n");
                                ret = -EIO;
                                break;

diff --git a/tests/fsck-tests/005-bad-item-offset.img b/tests/fsck-tests/005-bad-item-offset.img
new file mode 100644 (file)
index 0000000..e11e1e3
Binary files /dev/null and b/tests/fsck-tests/005-bad-item-offset.img differ