* Andreas Dilger <adilger@xxxxxxxxx>:
>
> > On May 10, 2017, at 4:04 PM, Eric Whitney <enwlinux@xxxxxxxxx> wrote:
> >
> > As e2fsck processes each file in pass1, the actual file system quota is
> > increased by the number of blocks discovered in the file. This can
> > include both non-multiply-claimed and multiply-claimed blocks, if the
> > latter exist. However, if a file containing multiply-claimed blocks
> > is then deleted in pass1b, those blocks are not taken into account when
> > decreasing the actual quota. In this case, the new quota values written
> > to the file system by e2fsck overstate the space actually consumed.
> > And, e2fsck must be run twice on the file system to fully correct
> > quota.
> >
> > Fix this by counting multiply-claimed blocks as a debit to quota when
> > deleting files in pass1b.
>
> Nice catch. It would be good to have an e2fsck test case that checks this.
> Also, one minor code style nit (or possibly defect) below.
Yeah, there's not much test coverage in this area. I'll look at it.
>
> > Signed-off-by: Eric Whitney <enwlinux@xxxxxxxxx>
> > ---
> > e2fsck/pass1b.c | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/e2fsck/pass1b.c b/e2fsck/pass1b.c
> > index b40f026..8744fad 100644
> > --- a/e2fsck/pass1b.c
> > +++ b/e2fsck/pass1b.c
> > @@ -636,11 +636,13 @@ static int delete_file_block(ext2_filsys fs,
> > lc = EXT2FS_B2C(fs, blockcnt);
> > if (ext2fs_test_block_bitmap2(ctx->block_dup_map, *block_nr)) {
> > n = dict_lookup(&clstr_dict, INT_TO_VOIDPTR(c));
> > - if (n) {
> > - p = (struct dup_cluster *) dnode_get(n);
> > - if (lc != pb->cur_cluster)
> > decrement_badcount(ctx, *block_nr, p);
> > - } else
> > + if (n)
> > + if (lc != pb->cur_cluster) {
> > + p = (struct dup_cluster *) dnode_get(n);
> > decrement_badcount(ctx, *block_nr, p);
> > + pb->dup_blocks++;
> > + }
> > + else
> > com_err("delete_file_block", 0,
> > _("internal error: can't find dup_blk for %llu\n"),
> > *block_nr);
>
> This is tricky to know which "if" the "else" is for without the added braces,
> and to be honest I don't even know what the C standard says about this, which
> is likely why the braces were there in the first place. I would instead
> recommend to add braces around the "else" clause to make it clear.
>
Yes, that's a classic dangling else bug - I scrubbed too hard. Thanks very
much for finding that. V2 coming along shortly.
Thanks for the review,
Eric
