4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: piaojun piaojun@huawei.com
[ Upstream commit d984187e3a1ad7d12447a7ab2c43ce3717a2b5b3 ]
We should not reuse the dirty bh in jbd2 directly due to the following situation:
1. When removing extent rec, we will dirty the bhs of extent rec and truncate log at the same time, and hand them over to jbd2.
2. The bhs are submitted to jbd2 area successfully.
3. The write-back thread of device help flush the bhs to disk but encounter write error due to abnormal storage link.
4. After a while the storage link become normal. Truncate log flush worker triggered by the next space reclaiming found the dirty bh of truncate log and clear its 'BH_Write_EIO' and then set it uptodate in __ocfs2_journal_access():
ocfs2_truncate_log_worker ocfs2_flush_truncate_log __ocfs2_flush_truncate_log ocfs2_replay_truncate_records ocfs2_journal_access_di __ocfs2_journal_access // here we clear io_error and set 'tl_bh' uptodata.
5. Then jbd2 will flush the bh of truncate log to disk, but the bh of extent rec is still in error state, and unfortunately nobody will take care of it.
6. At last the space of extent rec was not reduced, but truncate log flush worker have given it back to globalalloc. That will cause duplicate cluster problem which could be identified by fsck.ocfs2.
Sadly we can hardly revert this but set fs read-only in case of ruining atomicity and consistency of space reclaim.
Link: http://lkml.kernel.org/r/5A6E8092.8090701@huawei.com Fixes: acf8fdbe6afb ("ocfs2: do not BUG if buffer not uptodate in __ocfs2_journal_access") Signed-off-by: Jun Piao piaojun@huawei.com Reviewed-by: Yiwen Jiang jiangyiwen@huawei.com Reviewed-by: Changwei Ge ge.changwei@h3c.com Cc: Mark Fasheh mfasheh@versity.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Joseph Qi jiangqi903@gmail.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ocfs2/journal.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-)
--- a/fs/ocfs2/journal.c +++ b/fs/ocfs2/journal.c @@ -666,23 +666,24 @@ static int __ocfs2_journal_access(handle /* we can safely remove this assertion after testing. */ if (!buffer_uptodate(bh)) { mlog(ML_ERROR, "giving me a buffer that's not uptodate!\n"); - mlog(ML_ERROR, "b_blocknr=%llu\n", - (unsigned long long)bh->b_blocknr); + mlog(ML_ERROR, "b_blocknr=%llu, b_state=0x%lx\n", + (unsigned long long)bh->b_blocknr, bh->b_state);
lock_buffer(bh); /* - * A previous attempt to write this buffer head failed. - * Nothing we can do but to retry the write and hope for - * the best. + * A previous transaction with a couple of buffer heads fail + * to checkpoint, so all the bhs are marked as BH_Write_EIO. + * For current transaction, the bh is just among those error + * bhs which previous transaction handle. We can't just clear + * its BH_Write_EIO and reuse directly, since other bhs are + * not written to disk yet and that will cause metadata + * inconsistency. So we should set fs read-only to avoid + * further damage. */ if (buffer_write_io_error(bh) && !buffer_uptodate(bh)) { - clear_buffer_write_io_error(bh); - set_buffer_uptodate(bh); - } - - if (!buffer_uptodate(bh)) { unlock_buffer(bh); - return -EIO; + return ocfs2_error(osb->sb, "A previous attempt to " + "write this buffer head failed\n"); } unlock_buffer(bh); }