[PATCH 2/4] btrfs-progs: check/lowmem: Repair bad imode early

[Qu Wenruo]

For lowmem mode, if we hit a bad inode mode, normally it is reported
when we checking the DIR_INDEX/DIR_ITEM of the parent inode.

If we didn't repair at that timing, the error will be recorded even we
fixed it later.

So this patch will check for INODE_ITEM_MISMATCH error type, and if it's
really caused by invalid imode, repair it and clear the error.

Signed-off-by: Qu Wenruo <w...@suse.com>
---
 check/mode-lowmem.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
index 5f7f101daab1..5d0c520217fa 100644
--- a/check/mode-lowmem.c
+++ b/check/mode-lowmem.c
@@ -1550,6 +1550,35 @@ static int lowmem_delete_corrupted_dir_item(struct 
btrfs_root *root,
        return ret;
 }
 
+static int try_repair_imode(struct btrfs_root *root, u64 ino)
+{
+       struct btrfs_inode_item *iitem;
+       struct btrfs_path path;
+       struct btrfs_key key;
+       int ret;
+
+       key.objectid = ino;
+       key.type = BTRFS_INODE_ITEM_KEY;
+       key.offset = 0;
+       btrfs_init_path(&path);
+
+       ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+       if (ret > 0)
+               ret = -ENOENT;
+       if (ret < 0)
+               goto out;
+       iitem = btrfs_item_ptr(path.nodes[0], path.slots[0],
+                              struct btrfs_inode_item);
+       if (!is_valid_imode(btrfs_inode_mode(path.nodes[0], iitem))) {
+               ret = repair_imode_common(root, &path);
+       } else {
+               ret = -ENOTTY;
+       }
+out:
+       btrfs_release_path(&path);
+       return ret;
+}
+
 /*
  * Call repair_inode_item_missing and repair_ternary_lowmem to repair
  *
@@ -1574,6 +1603,16 @@ static int repair_dir_item(struct btrfs_root *root, 
struct btrfs_key *di_key,
                        err &= ~(INODE_ITEM_MISMATCH | INODE_ITEM_MISSING);
        }
 
+       if (err & INODE_ITEM_MISMATCH) {
+               /*
+                * INODE_ITEM mismatch can be caused by bad imode,
+                * so check if it's a bad imode, then repair if possible.
+                */
+               ret = try_repair_imode(root, ino);
+               if (!ret)
+                       err &= ~INODE_ITEM_MISMATCH;
+       }
+
        if (err & ~(INODE_ITEM_MISMATCH | INODE_ITEM_MISSING)) {
                ret = repair_ternary_lowmem(root, dirid, ino, index, namebuf,
                                            name_len, filetype, err);
-- 
2.23.0