On 3.09.19 г. 11:24 ч., Qu Wenruo wrote:
> Before this patch, repair_imode_common() can only handle two types of
> inodes:
> - Free space cache inodes
> - ROOT DIR inodes
>
> For inodes in subvolume trees, the problem is how to determine the
> correct imode, thus it was not implemented.
>
> However there are more reports of incorrect imode in subvolume trees, we
> need to support such fix.
>
> So this patch adds a new function, detect_imode(), to detect (or call it
> educated guess) imode for inodes in subvolume trees.
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> check/mode-common.c | 96 +++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 83 insertions(+), 13 deletions(-)
>
> diff --git a/check/mode-common.c b/check/mode-common.c
> index 195b6efaa7aa..807d7daf98a6 100644
> --- a/check/mode-common.c
> +++ b/check/mode-common.c
> @@ -836,6 +836,80 @@ int reset_imode(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> return ret;
> }
>
> +static int detect_imode(struct btrfs_root *root, struct btrfs_path *path,
> + u32 *imode_ret)
> +{
> + struct btrfs_key key;
> + struct btrfs_inode_item *iitem;
> + const u32 priv = 0700;
> + u64 ino;
> + u32 imode = S_IFREG;
> + int ret = 0;
> +
> + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
> + ino = key.objectid;
> + iitem = btrfs_item_ptr(path->nodes[0], path->slots[0],
> + struct btrfs_inode_item);
> +
> + /*
> + * Both CHR and BLK uses rdev, no way to distinguish them, so fall back
> + * to BLK.
> + */
> + if (btrfs_inode_rdev(path->nodes[0], iitem) != 0) {
> + imode = S_IFBLK;
> + goto out;
> + }
> +
> + /* root inode */
> + if (ino == BTRFS_FIRST_FREE_OBJECTID) {
> + imode = S_IFDIR;
> + goto out;
> + }
> +
> + while (1) {
> + ret = btrfs_next_item(root, path);
> + if (ret > 0) {
> + /* No determining result found, falls back to REG */
> + ret = 0;
> + goto out;
> + }
> + if (ret < 0)
> + goto out;
> + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
> + if (key.objectid != ino)
> + goto out;
> +
> + /*
> + * We ignore some types to make life easier:
> + * - INODE_REF
> + * We need to do a full tree search, which can fail for
> + * corrupted fs, but not worthy compared to other easier
> + * to determine types.
> + * - XATTR
> + * Both REG and DIR can have xattr, so not useful
> + */
> + switch (key.type) {
> + case BTRFS_DIR_ITEM_KEY:
> + case BTRFS_DIR_INDEX_KEY:
> + imode = S_IFDIR;
> + goto out;
> + case BTRFS_EXTENT_DATA_KEY:
> + /*
> + * Both REG and LINK could have EXTENT_DATA.
> + * We just fall back to REG as user can inspect the
> + * content.
> + */
> + imode = S_IFREG;
> + goto out;
> + }
> + }
> +
> +out:
> + /* Set default value even when something wrong happened */
> + *imode_ret = (imode | priv);
> + return ret;
> +}
> +
> /*
> * Reset the inode mode of the inode specified by @path.
> *
> @@ -852,22 +926,18 @@ int repair_imode_common(struct btrfs_root *root, struct btrfs_path *path)
> u32 imode;
> int ret;
>
> - if (root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID) {
> - error(
> - "repair inode mode outside of root tree is not supported yet");
> - return -ENOTTY;
> - }
> btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
> ASSERT(key.type == BTRFS_INODE_ITEM_KEY);
> - if (key.objectid != BTRFS_ROOT_TREE_DIR_OBJECTID &&
> - !is_fstree(key.objectid)) {
> - error("unsupported ino %llu", key.objectid);
> - return -ENOTTY;
> + if (root->objectid == BTRFS_ROOT_TREE_OBJECTID) {
> + /* In root tree we only have two possible imode */
> + if (key.objectid == BTRFS_ROOT_TREE_OBJECTID)
> + imode = S_IFDIR | 0755;
> + else
> + imode = S_IFREG | 0600;
> + } else {
> + detect_imode(root, path, &imode);
> + /* Ignore error returned, just use the default value returned */
Is this safe enough though? What if due to an error a directory is
corrected to be file? Let's not forget the context we are oprating here
- a broken fs so it's possible (if not likely) that any of the search
functions inside detect_imode could return negative error value. OTOH
I'd expect the transaction commit to fail if that's the case e.g. faulty
device.
> }
> - if (key.objectid == BTRFS_ROOT_TREE_DIR_OBJECTID)
> - imode = 040755;
> - else
> - imode = 0100600;
>
> trans = btrfs_start_transaction(root, 1);
> if (IS_ERR(trans)) {
>
