Hi, On Tue 02-04-19 12:11:33, Jiufei Xue wrote: > can I get your Acked-by? Ted, tracks patches in patchwork and he processes less important fixes in bigger batches when he has time. So don't be afraid, your patch is not lost :) Honza > > Thanks, > Jiufei > > On 2019/3/28 下午6:07, Jiufei Xue wrote: > > We hit a BUG at fs/buffer.c:3057 if we detached the nbd device > > before unmounting ext4 filesystem. > > > > The typical chain of events leading to the BUG: > > jbd2_write_superblock > > submit_bh > > submit_bh_wbc > > BUG_ON(!buffer_mapped(bh)); > > > > The block device is removed and all the pages are invalidated. JBD2 > > was trying to write journal superblock to the block device which is > > no longer present. > > > > Fix this by checking the journal superblock's buffer head prior to > > submitting. > > > > Cc: stable@xxxxxxxxxx > > Reported-by: Eric Ren <renzhen@xxxxxxxxxxxxxxxxx> > > Signed-off-by: Jiufei Xue <jiufei.xue@xxxxxxxxxxxxxxxxx> > > Reviewed-by: Jan Kara <jack@xxxxxxx> > > --- > > fs/jbd2/journal.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c > > index 382c030cc78b..37e16d969925 100644 > > --- a/fs/jbd2/journal.c > > +++ b/fs/jbd2/journal.c > > @@ -1350,6 +1350,10 @@ static int jbd2_write_superblock(journal_t *journal, int write_flags) > > journal_superblock_t *sb = journal->j_superblock; > > int ret; > > > > + /* Buffer got discarded which means block device got invalidated */ > > + if (!buffer_mapped(bh)) > > + return -EIO; > > + > > trace_jbd2_write_superblock(journal, write_flags); > > if (!(journal->j_flags & JBD2_BARRIER)) > > write_flags &= ~(REQ_FUA | REQ_PREFLUSH); -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
