On Mon 02-11-20 14:30:37, Andreas Dilger wrote:
> On Nov 2, 2020, at 10:27 AM, Jan Kara <jack@xxxxxxx> wrote:
> >
> > The on-disk quota format supports quota files with upto 2^32 blocks. Be
> > careful when computing quota file offsets in the quota files from block
> > numbers as they can overflow 32-bit types. Since quota files larger than
> > 4GB would require ~26 millions of quota users, this is mostly a
> > theoretical concern now but better be careful, fuzzers would find the
> > problem sooner or later anyway...
> >
> > Signed-off-by: Jan Kara <jack@xxxxxxx>
>
> Out of curiosity, is this 26 million *quota entries*, or is it just a UID
> larger than 26M? At one point the quota files were sparse and indexed by
> the UID, but I guess very file name "quota tree" means this is not correct.
> Is there some document/comment that describes the on-disk quota file format?
It is really 26M different UIDs/GIDs/ProjectIDs. The sparse file format you
describe is the original quota format (implemented by fs/quota/quota_v1.c)
that the current format superseeded sometime in 1999 or so ;). The current
format uses radix tree for structure lookup and then structures are just
stored in a linear array. There's documentation of the format in
quota-tools in doc/quotadoc.sgml.
> In any case, the change makes sense regardless, since ->quota_read() takes
> loff_t for the offset.
>
> Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
Thanks!
Honza
>
> > ---
> > fs/quota/quota_tree.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
> > index a6f856f341dc..c5562c871c8b 100644
> > --- a/fs/quota/quota_tree.c
> > +++ b/fs/quota/quota_tree.c
> > @@ -62,7 +62,7 @@ static ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
> >
> > memset(buf, 0, info->dqi_usable_bs);
> > return sb->s_op->quota_read(sb, info->dqi_type, buf,
> > - info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
> > + info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
> > }
> >
> > static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
> > @@ -71,7 +71,7 @@ static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
> > ssize_t ret;
> >
> > ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
> > - info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
> > + info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
> > if (ret != info->dqi_usable_bs) {
> > quota_error(sb, "dquota write failed");
> > if (ret >= 0)
> > @@ -284,7 +284,7 @@ static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
> > blk);
> > goto out_buf;
> > }
> > - dquot->dq_off = (blk << info->dqi_blocksize_bits) +
> > + dquot->dq_off = ((loff_t)blk << info->dqi_blocksize_bits) +
> > sizeof(struct qt_disk_dqdbheader) +
> > i * info->dqi_entry_size;
> > kfree(buf);
> > @@ -559,7 +559,7 @@ static loff_t find_block_dqentry(struct qtree_mem_dqinfo *info,
> > ret = -EIO;
> > goto out_buf;
> > } else {
> > - ret = (blk << info->dqi_blocksize_bits) + sizeof(struct
> > + ret = ((loff_t)blk << info->dqi_blocksize_bits) + sizeof(struct
> > qt_disk_dqdbheader) + i * info->dqi_entry_size;
> > }
> > out_buf:
> > --
> > 2.16.4
> >
>
>
> Cheers, Andreas
>
>
>
>
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
