From: Josef Bacik <josef@toxicpanda.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Josef Bacik <josef@toxicpanda.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"zhengbin (A)" <zhengbin13@huawei.com>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"zhangyi (F)" <yi.zhang@huawei.com>,
renxudong1@huawei.com, Hou Tao <houtao1@huawei.com>,
linux-btrfs@vger.kernel.org, "Yan, Zheng" <zyan@redhat.com>,
linux-cifs@vger.kernel.org, Steve French <sfrench@us.ibm.com>
Subject: Re: [PATCH] Re: Possible FS race condition between iterate_dir and d_alloc_parallel
Date: Tue, 24 Sep 2019 11:26:28 -0400 [thread overview]
Message-ID: <20190924152627.kmbvxb4elpxfoybf@macbook-pro-91.dhcp.thefacebook.com> (raw)
In-Reply-To: <20190924151107.GF26530@ZenIV.linux.org.uk>
On Tue, Sep 24, 2019 at 04:11:07PM +0100, Al Viro wrote:
> On Tue, Sep 24, 2019 at 11:01:45AM -0400, Josef Bacik wrote:
>
> > Sorry I mis-read the code a little bit. This is purely for the subvolume link
> > directories. We haven't wandered down into this directory yet. If the
> > subvolume is being deleted and we still have the fake directory entry for it
> > then we just populate it with this dummy inode and then we can't lookup anything
> > underneath it. Thanks,
>
> Umm... OK, I guess my question would be better stated a bit differently: we
> have a directory inode, with btrfs_lookup() for lookups in it *and* with
> dcache_readdir() called when you try to do getdents(2) on that thing.
> How does that work?
Sorry I hadn't read through the context. We won't end up with things under this
directory. The lookup will try to look up into the subvolume, see that it's
empty, and just return nothing. There should never be any entries that end up
under this dummy entry. Thanks,
Josef
next prev parent reply other threads:[~2019-09-24 15:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAHk-=whpKgNTxjrenAed2sNkegrpCCPkV77_pWKbqo+c7apCOw@mail.gmail.com>
[not found] ` <20190914170146.GT1131@ZenIV.linux.org.uk>
[not found] ` <CAHk-=wiPv+yo86GpA+Gd_et0KS2Cydk4gSbEj3p4S4tEb1roKw@mail.gmail.com>
[not found] ` <20190914200412.GU1131@ZenIV.linux.org.uk>
[not found] ` <CAHk-=whpoQ_hX2KeqjQs3DeX6Wb4Tmb8BkHa5zr-Xu=S55+ORg@mail.gmail.com>
[not found] ` <20190915005046.GV1131@ZenIV.linux.org.uk>
[not found] ` <CAHk-=wjcZBB2GpGP-cxXppzW=M0EuFnSLoTXHyqJ4BtffYrCXw@mail.gmail.com>
[not found] ` <20190915160236.GW1131@ZenIV.linux.org.uk>
[not found] ` <CAHk-=whjNE+_oSBP_o_9mquUKsJn4gomL2f0MM79gxk_SkYLRw@mail.gmail.com>
[not found] ` <20190921140731.GQ1131@ZenIV.linux.org.uk>
2019-09-24 2:52 ` [PATCH] Re: Possible FS race condition between iterate_dir and d_alloc_parallel Al Viro
2019-09-24 13:30 ` Josef Bacik
2019-09-24 14:51 ` Al Viro
2019-09-24 15:01 ` Josef Bacik
2019-09-24 15:11 ` Al Viro
2019-09-24 15:26 ` Josef Bacik [this message]
2019-09-24 16:33 ` Al Viro
[not found] ` <CAHk-=wiJ1eY7y6r_cFNRPCqD+BJZS7eJeQFO6OrXxRFjDAipsQ@mail.gmail.com>
2019-09-29 5:29 ` Al Viro
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=20190924152627.kmbvxb4elpxfoybf@macbook-pro-91.dhcp.thefacebook.com \
--to=josef@toxicpanda.com \
--cc=akpm@linux-foundation.org \
--cc=houtao1@huawei.com \
--cc=jack@suse.cz \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-cifs@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=renxudong1@huawei.com \
--cc=sfrench@us.ibm.com \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=yi.zhang@huawei.com \
--cc=zhengbin13@huawei.com \
--cc=zyan@redhat.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).