Hi Andrew, Please send this bug-fix to upstream. It fixes a file system corruption problem in a near disk full condition.
Thanks, Ryusuke Konishi On Thu, 9 Jan 2014 02:22:15 +0900, Ryusuke Konishi wrote: > From: Andreas Rohner <[email protected]> > > There is a bug in the function nilfs_segctor_collect, which results in > active data being written to a segment, that is marked as clean. It is > possible, that this segment is selected for a later segment > construction, whereby the old data is overwritten. > > The problem shows itself with the following kernel log message: > > nilfs_sufile_do_cancel_free: segment 6533 must be clean > > Usually a few hours later the file system gets corrupted: > > NILFS: bad btree node (blocknr=8748107): level = 0, flags = 0x0, > nchildren = 0 > NILFS error (device sdc1): nilfs_bmap_last_key: broken bmap > (inode number=114660) > > The issue can be reproduced with a file system that is nearly full and > with the cleaner running, while some IO intensive task is running. > Although it is quite hard to reproduce. > > This is what happens: > > 1. The cleaner starts the segment construction > 2. nilfs_segctor_collect is called > 3. sc_stage is on NILFS_ST_SUFILE and segments are freed > 4. sc_stage is on NILFS_ST_DAT current segment is full > 5. nilfs_segctor_extend_segments is called, which > allocates a new segment > 6. The new segment is one of the segments freed in step 3 > 7. nilfs_sufile_cancel_freev is called and produces an error message > 8. Loop around and the collection starts again > 9. sc_stage is on NILFS_ST_SUFILE and segments are freed > including the newly allocated segment, which will contain active data > and can be allocated at a later time > 10. A few hours later another segment construction allocates the segment > and causes file system corruption > > This can be prevented by simply reordering the statements. If > nilfs_sufile_cancel_freev is called before nilfs_segctor_extend_segments > the freed segments are marked as dirty and cannot be allocated any more. > > Signed-off-by: Andreas Rohner <[email protected]> > Reviewed-by: Ryusuke Konishi <[email protected]> > Tested-by: Andreas Rohner <[email protected]> > Cc: stable <[email protected]> > Signed-off-by: Ryusuke Konishi <[email protected]> > --- > fs/nilfs2/segment.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c > index 9f6b486..a1a1916 100644 > --- a/fs/nilfs2/segment.c > +++ b/fs/nilfs2/segment.c > @@ -1440,17 +1440,19 @@ static int nilfs_segctor_collect(struct nilfs_sc_info > *sci, > > nilfs_clear_logs(&sci->sc_segbufs); > > - err = nilfs_segctor_extend_segments(sci, nilfs, nadd); > - if (unlikely(err)) > - return err; > - > if (sci->sc_stage.flags & NILFS_CF_SUFREED) { > err = nilfs_sufile_cancel_freev(nilfs->ns_sufile, > sci->sc_freesegs, > sci->sc_nfreesegs, > NULL); > WARN_ON(err); /* do not happen */ > + sci->sc_stage.flags &= ~NILFS_CF_SUFREED; > } > + > + err = nilfs_segctor_extend_segments(sci, nilfs, nadd); > + if (unlikely(err)) > + return err; > + > nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA); > sci->sc_stage = prev_stage; > } > -- > 1.7.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
