erofs-utils: fix up unchanged directory pNIDs for incremental builds

For incremental builds, it's unnecessary to dump all unchanged
directories, yet the pNIDs of those directories need to be fixed to
the new parent on-disk inodes.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240618082414.47876-5-hsiangkao@linux.alibaba.com

diff --git a/lib/inode.c b/lib/inode.c
index 321b2f5b27a6f3bc595a7305ad44b8ce8674d43f..6c4fa2a2d93dcf694c625e5cbb5608ba8b86909e 100644 (file)
--- a/lib/inode.c
+++ b/lib/inode.c
@@ -338,6 +338,84 @@ static void erofs_d_invalidate(struct erofs_dentry *d)
        erofs_iput(inode);
 }
 
+static int erofs_rebuild_inode_fix_pnid(struct erofs_inode *parent,
+                                       erofs_nid_t nid)
+{
+       struct erofs_inode dir = {
+               .sbi = parent->sbi,
+               .nid = nid
+       };
+       unsigned int bsz = erofs_blksiz(dir.sbi);
+       unsigned int err, isz;
+       erofs_off_t boff, off;
+       erofs_nid_t pnid;
+       bool fixed = false;
+
+       err = erofs_read_inode_from_disk(&dir);
+       if (err)
+               return err;
+
+       if (!S_ISDIR(dir.i_mode))
+               return -ENOTDIR;
+
+       if (dir.datalayout != EROFS_INODE_FLAT_INLINE &&
+           dir.datalayout != EROFS_INODE_FLAT_PLAIN)
+               return -EOPNOTSUPP;
+
+       pnid = erofs_lookupnid(parent);
+       isz = dir.inode_isize + dir.xattr_isize;
+       boff = erofs_pos(dir.sbi, dir.u.i_blkaddr);
+       for (off = 0; off < dir.i_size; off += bsz) {
+               char buf[EROFS_MAX_BLOCK_SIZE];
+               struct erofs_dirent *de = (struct erofs_dirent *)buf;
+               unsigned int nameoff, count, de_nameoff;
+
+               count = min_t(erofs_off_t, bsz, dir.i_size - off);
+               err = erofs_pread(&dir, buf, count, off);
+               if (err)
+                       return err;
+
+               nameoff = le16_to_cpu(de->nameoff);
+               if (nameoff < sizeof(struct erofs_dirent) ||
+                   nameoff >= count) {
+                       erofs_err("invalid de[0].nameoff %u @ nid %llu, offset %llu",
+                                 nameoff, dir.nid | 0ULL, off | 0ULL);
+                       return -EFSCORRUPTED;
+               }
+
+               while ((char *)de < buf + nameoff) {
+                       de_nameoff = le16_to_cpu(de->nameoff);
+                       if (((char *)(de + 1) >= buf + nameoff ?
+                               strnlen(buf + de_nameoff, count - de_nameoff) == 2 :
+                               le16_to_cpu(de[1].nameoff) == de_nameoff + 2) &&
+                          !memcmp(buf + de_nameoff, "..", 2)) {
+                               if (de->nid == cpu_to_le64(pnid))
+                                       return 0;
+                               de->nid = cpu_to_le64(pnid);
+                               fixed = true;
+                               break;
+                       }
+                       ++de;
+               }
+
+               if (!fixed)
+                       continue;
+               err = erofs_dev_write(dir.sbi, buf,
+                       (off + bsz > dir.i_size &&
+                               dir.datalayout == EROFS_INODE_FLAT_INLINE ?
+                               erofs_iloc(&dir) + isz : boff + off), count);
+               erofs_dbg("directory %llu pNID is updated to %llu",
+                         nid | 0ULL, pnid | 0ULL);
+               break;
+       }
+       if (err || fixed)
+               return err;
+
+       erofs_err("directory data %llu is corrupted (\"..\" not found)",
+                 nid | 0ULL);
+       return -EFSCORRUPTED;
+}
+
 static int erofs_write_dir_file(struct erofs_inode *dir)
 {
        struct erofs_dentry *head = list_first_entry(&dir->i_subdirs,
@@ -359,6 +437,13 @@ static int erofs_write_dir_file(struct erofs_inode *dir)
                const unsigned int len = strlen(d->name) +
                        sizeof(struct erofs_dirent);
 
+               /* XXX: a bit hacky, but to avoid another traversal */
+               if (d->validnid && d->type == EROFS_FT_DIR) {
+                       ret = erofs_rebuild_inode_fix_pnid(dir, d->nid);
+                       if (ret)
+                               return ret;
+               }
+
                erofs_d_invalidate(d);
                if (used + len > erofs_blksiz(sbi)) {
                        ret = write_dirblock(sbi, q, head, d,
@@ -1193,7 +1278,9 @@ static int erofs_mkfs_jobfn(struct erofs_mkfs_jobitem *item)
        }
 
        if (item->type == EROFS_MKFS_JOB_DIR_BH) {
-               erofs_write_dir_file(inode);
+               ret = erofs_write_dir_file(inode);
+               if (ret)
+                       return ret;
                erofs_write_tail_end(inode);
                inode->bh->op = &erofs_write_inode_bhops;
                erofs_iput(inode);