On Sat, May 26, 2018 at 08:29:35PM +0800, Lu Fengqi wrote:
> On Sat, May 26, 2018 at 07:42:46AM -0400, Jeff Layton wrote:
> >On Sat, 2018-05-26 at 10:42 +0800, Lu Fengqi wrote:
> >> Creating a file reuses the inode object by kmem_cache_alloc without
> >> initializing maping->wb_err. If it contains an unseen writeback error,
> >> fsync will report an error on the file, even if no error has ever occurred
> >> after the file was created.
> >>
> >> Before commit b4678df184b3 ("errseq: Always report a writeback error
> >> once"), any errors that occur before the file descriptor is opened will be
> >> ignored, causing the issue not to be found. Afterward, any unseen writeback
> >> error will be reported once, including, of course, the uninitialized
> >> maping->wb_err, which exposes this problem.
> >>
> >> Signed-off-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
> >> ---
> >> fs/inode.c | 1 +
> >> 1 file changed, 1 insertion(+)
> >>
> >> diff --git a/fs/inode.c b/fs/inode.c
> >> index 13ceb98c3bd3..bf02dc9d1837 100644
> >> --- a/fs/inode.c
> >> +++ b/fs/inode.c
> >> @@ -182,6 +182,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
> >> mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
> >> mapping->private_data = NULL;
> >> mapping->writeback_index = 0;
> >> + mapping->wb_err = 0;
> >> inode->i_private = NULL;
> >> inode->i_mapping = mapping;
> >> INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
> >
> >(cc'ing Darrick)
> >
> >I think Darrick had a similar patch that also fixed up some related
> >inode reuse issues in xfs. Darrick, were you planning to get that
> >merged for v4.17?
>
> Oh, I missed Darrick's patch. Thanks for your reminder.
Yeah, it's in my for-next branch now, will send it to Linus as a last
minute fix after it's been through the -next wringer (i.e. tomorrow)
unless anyone yells.
--D
>
> --
> Thanks,
> Lu
>
> >--
> >Jeff Layton <jlayton@xxxxxxxxxx>
> >
> >
>
>
