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ubifs: Re-statistic cleaned znode count if commit failed

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Dirty znodes will be written on flash in committing process with
following states:

	      process A			|  znode state
------------------------------------------------------
do_commit				| DIRTY_ZNODE
  ubifs_tnc_start_commit		| DIRTY_ZNODE
   get_znodes_to_commit			| DIRTY_ZNODE | COW_ZNODE
    layout_commit			| DIRTY_ZNODE | COW_ZNODE
     fill_gap                           | 0
  write master				| 0 or OBSOLETE_ZNODE

	      process B			|  znode state
------------------------------------------------------
do_commit				| DIRTY_ZNODE[1]
  ubifs_tnc_start_commit		| DIRTY_ZNODE
   get_znodes_to_commit			| DIRTY_ZNODE | COW_ZNODE
  ubifs_tnc_end_commit			| DIRTY_ZNODE | COW_ZNODE
   write_index                          | 0
  write master				| 0 or OBSOLETE_ZNODE[2] or
					| DIRTY_ZNODE[3]

[1] znode is dirtied without concurrent committing process
[2] znode is copied up (re-dirtied by other process) before cleaned
    up in committing process
[3] znode is re-dirtied after cleaned up in committing process

Currently, the clean znode count is updated in free_obsolete_znodes(),
which is called only in normal path. If do_commit failed, clean znode
count won't be updated, which triggers a failure ubifs assertion[4] in
ubifs_tnc_close():
 ubifs_assert_failed [ubifs]: UBIFS assert failed: freed == n

[4] Commit 380347e9ca ("UBIFS: Add an assertion for clean_zn_cnt").

Fix it by re-statisticing cleaned znode count in tnc_destroy_cnext().

Fetch a reproducer in [Link].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216704
Fixes: 1e51764a3c ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Zhihao Cheng 2022-11-18 17:02:35 +08:00 committed by Richard Weinberger
parent 2de203d8ab
commit 944e096aa2
1 changed files with 15 additions and 0 deletions
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15
fs/ubifs/tnc.c
View File

@ -3053,6 +3053,21 @@ static void tnc_destroy_cnext(struct ubifs_info *c)
cnext = cnext->cnext;
if (ubifs_zn_obsolete(znode))
kfree(znode);
else if (!ubifs_zn_cow(znode)) {
/*
* Don't forget to update clean znode count after
* committing failed, because ubifs will check this
* count while closing tnc. Non-obsolete znode could
* be re-dirtied during committing process, so dirty
* flag is untrustable. The flag 'COW_ZNODE' is set
* for each dirty znode before committing, and it is
* cleared as long as the znode become clean, so we
* can statistic clean znode count according to this
* flag.
*/
atomic_long_inc(&c->clean_zn_cnt);
atomic_long_inc(&ubifs_clean_zn_cnt);
}
} while (cnext && cnext != c->cnext);
}