From: Jan Kara <jack@suse.cz>
To: Steve Magnani <steve.magnani@digidescorp.com>
Cc: Jan Kara <jack@suse.cz>, Jan Kara <jack@suse.com>,
"Steven J . Magnani" <steve@digidescorp.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] udf: reduce leakage of blocks related to named streams
Date: Mon, 26 Aug 2019 11:14:21 +0200 [thread overview]
Message-ID: <20190826091421.GB10614@quack2.suse.cz> (raw)
In-Reply-To: <4169b326-a8ff-5fc4-0e5e-393569273267@digidescorp.com>
On Mon 19-08-19 07:10:24, Steve Magnani wrote:
> Jan -
>
>
> On 8/15/19 7:42 AM, Jan Kara wrote:
> > On Wed 14-08-19 07:50:02, Steven J. Magnani wrote:
> > > Windows is capable of creating UDF files having named streams.
> > > One example is the "Zone.Identifier" stream attached automatically
> > > to files downloaded from a network. See:
> > > https://msdn.microsoft.com/en-us/library/dn392609.aspx
> > >
> > > Modification of a file having one or more named streams in Linux causes
> > > the stream directory to become detached from the file, essentially leaking
> > > all blocks pertaining to the file's streams.
> > >
> > > Fix by saving off information about an inode's streams when reading it,
> > > for later use when its on-disk data is updated.
> > > <snip>
> > > } else {
> > > inode->i_blocks = le64_to_cpu(efe->logicalBlocksRecorded) <<
> > > (inode->i_sb->s_blocksize_bits - 9);
> > > @@ -1498,6 +1502,16 @@ reread:
> > > iinfo->i_lenEAttr = le32_to_cpu(efe->lengthExtendedAttr);
> > > iinfo->i_lenAlloc = le32_to_cpu(efe->lengthAllocDescs);
> > > iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
> > > +
> > > + /* Named streams */
> > > + iinfo->i_streamdir = (efe->streamDirectoryICB.extLength != 0);
> > > + iinfo->i_locStreamdir =
> > > + lelb_to_cpu(efe->streamDirectoryICB.extLocation);
> > > + iinfo->i_lenStreams = le64_to_cpu(efe->objectSize);
> > > + if (iinfo->i_lenStreams >= inode->i_size)
> > > + iinfo->i_lenStreams -= inode->i_size;
> > > + else
> > > + iinfo->i_lenStreams = 0;
> > Hum, maybe you could just have i_objectSize instead of i_lenStreams? You
> > use the field just to preserve objectSize anyway so there's no point in
> > complicating it.
> >
>
> I started making this change and found that it actually complicates things more,
> by forcing the driver to update i_objectSize everywhere that i_size is changed.
> Are you sure this is what you want?
Aha, that's a good point! No, in that case what you did was better. I'll
just take your v2 patch then, I can make the other minor adjustments I was
suggesting when applying the patch. Thanks for looking into this!
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
prev parent reply other threads:[~2019-08-26 9:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-14 12:50 [PATCH v2] udf: reduce leakage of blocks related to named streams Steven J. Magnani
2019-08-15 12:42 ` Jan Kara
2019-08-19 12:10 ` Steve Magnani
2019-08-26 9:14 ` Jan Kara [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190826091421.GB10614@quack2.suse.cz \
--to=jack@suse.cz \
--cc=jack@suse.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=steve.magnani@digidescorp.com \
--cc=steve@digidescorp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).