> Hello Namjae Jeon,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch e43bb4e612b4: "ext4: decrement free clusters/inodes
> counters when block group declared bad" from Jun 26, 2014, leads to
> the following Smatch complaint:
>
Hi Dan.
Thanks for your report!!
I will send the proper patch to fix this issue.
> fs/ext4/ialloc.c:343 ext4_free_inode()
> error: we previously assumed 'gdp' could be null (see line 300)
>
> fs/ext4/ialloc.c
> 299 gdp = ext4_get_group_desc(sb, block_group, &bh2);
> 300 if (gdp) {
> ^^^
> Check for NULL.
>
> 301 BUFFER_TRACE(bh2, "get_write_access");
> 302 fatal = ext4_journal_get_write_access(handle, bh2);
> 303 }
> 304 ext4_lock_group(sb, block_group);
> 305 cleared = ext4_test_and_clear_bit(bit, bitmap_bh->b_data);
> 306 if (fatal || !cleared) {
> 307 ext4_unlock_group(sb, block_group);
> 308 goto out;
> 309 }
> 310
> 311 count = ext4_free_inodes_count(sb, gdp) + 1;
> 312 ext4_free_inodes_set(sb, gdp, count);
> 313 if (is_directory) {
> 314 count = ext4_used_dirs_count(sb, gdp) - 1;
> 315 ext4_used_dirs_set(sb, gdp, count);
> 316 percpu_counter_dec(&sbi->s_dirs_counter);
> 317 }
> 318 ext4_inode_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
> 319 EXT4_INODES_PER_GROUP(sb) / 8);
> 320 ext4_group_desc_csum_set(sb, block_group, gdp);
> 321 ext4_unlock_group(sb, block_group);
> 322
> 323 percpu_counter_inc(&sbi->s_freeinodes_counter);
> 324 if (sbi->s_log_groups_per_flex) {
> 325 ext4_group_t f = ext4_flex_group(sbi, block_group);
> 326
> 327 atomic_inc(&sbi->s_flex_groups[f].free_inodes);
> 328 if (is_directory)
> 329 atomic_dec(&sbi->s_flex_groups[f].used_dirs);
> 330 }
> 331 BUFFER_TRACE(bh2, "call ext4_handle_dirty_metadata");
> 332 fatal = ext4_handle_dirty_metadata(handle, NULL, bh2);
> 333 out:
> 334 if (cleared) {
> 335 BUFFER_TRACE(bitmap_bh, "call ext4_handle_dirty_metadata");
> 336 err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
> 337 if (!fatal)
> 338 fatal = err;
> 339 } else {
> 340 ext4_error(sb, "bit already cleared for inode %lu", ino);
> 341 if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
> 342 int count;
> 343 count = ext4_free_inodes_count(sb, gdp);
> ^^^
> Patch adds new unchecked dereference inside the function call.
>
> 344 percpu_counter_sub(&sbi->s_freeinodes_counter,
> 345 count);
>
> regards,
> dan carpenter
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