From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [git pull] vfs fixes
Date: Mon, 3 Apr 2017 01:43:14 +0100 [thread overview]
Message-ID: <20170403004314.GL29622@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170403003045.GK29622@ZenIV.linux.org.uk>
On Mon, Apr 03, 2017 at 01:30:45AM +0100, Al Viro wrote:
> Currently true and almost certainly will remain so. Point taken, what you
> are suggesting is better. Actually, the invariant to watch for is
> "no d_can_lookup() withtout DCACHE_RCUACCESS" and that we can trivially
> enforce by one-liner change in d_flags_for_inode() -
> s/DCACHE_DIRECTORY_TYPE/& | DCACHE_RCUACCESS/
>
> OK...
Do you have any objections against the following (still untested) variant?
I don't see any point in checking for flags & LOOKUP_RCU in case of !*s -
flags is in register at that point, so...
diff --git a/fs/dcache.c b/fs/dcache.c
index 95d71eda8142..05550139a8a6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1757,7 +1757,13 @@ static unsigned d_flags_for_inode(struct inode *inode)
return DCACHE_MISS_TYPE;
if (S_ISDIR(inode->i_mode)) {
- add_flags = DCACHE_DIRECTORY_TYPE;
+ /*
+ * Any potential starting point of lookup should have
+ * DCACHE_RCUACCESS; currently directory dentries
+ * come from d_alloc() anyway, but it costs us nothing
+ * to enforce it here.
+ */
+ add_flags = DCACHE_DIRECTORY_TYPE | DCACHE_RCUACCESS;
if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
if (unlikely(!inode->i_op->lookup))
add_flags = DCACHE_AUTODIR_TYPE;
diff --git a/fs/namei.c b/fs/namei.c
index d41fab78798b..19dcf62133cc 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2145,6 +2145,9 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
int retval = 0;
const char *s = nd->name->name;
+ if (!*s)
+ flags &= ~LOOKUP_RCU;
+
nd->last_type = LAST_ROOT; /* if there are only slashes... */
nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
nd->depth = 0;
next prev parent reply other threads:[~2017-04-03 0:43 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-02 17:01 [git pull] vfs fixes Al Viro
2017-04-02 23:59 ` Linus Torvalds
2017-04-03 0:10 ` Linus Torvalds
2017-04-03 0:30 ` Al Viro
2017-04-03 0:43 ` Al Viro [this message]
2017-04-03 0:58 ` Linus Torvalds
2017-04-03 2:21 ` Al Viro
2017-04-03 6:00 ` Eric W. Biederman
2017-04-03 7:46 ` Al Viro
2017-04-04 0:22 ` Ian Kent
2017-04-04 0:47 ` Ian Kent
2017-04-03 0:20 ` Al Viro
-- strict thread matches above, loose matches on Subject: below --
2024-06-10 14:09 [GIT PULL] " Christian Brauner
2024-06-11 19:15 ` Linus Torvalds
2024-06-11 23:42 ` pr-tracker-bot
2024-05-27 11:55 Christian Brauner
2024-05-27 15:30 ` pr-tracker-bot
2024-04-26 14:59 Christian Brauner
2024-04-26 18:09 ` pr-tracker-bot
2024-04-05 11:22 Christian Brauner
2024-04-05 17:09 ` pr-tracker-bot
2024-03-18 12:19 Christian Brauner
2024-03-18 16:48 ` pr-tracker-bot
2024-03-18 19:14 ` Linus Torvalds
2024-03-18 19:41 ` Linus Torvalds
2024-03-19 6:58 ` Christian Brauner
2024-03-20 10:21 ` Christian Brauner
2024-03-06 15:45 Christian Brauner
2024-03-06 16:33 ` pr-tracker-bot
2024-03-01 12:45 Christian Brauner
2024-03-01 20:37 ` pr-tracker-bot
2024-02-22 14:03 Christian Brauner
2024-02-22 18:18 ` pr-tracker-bot
2024-02-12 13:00 Christian Brauner
2024-02-12 17:03 ` pr-tracker-bot
2024-01-13 12:31 Christian Brauner
2024-01-17 20:03 ` pr-tracker-bot
2023-11-24 10:27 Christian Brauner
2023-11-24 18:25 ` Linus Torvalds
2023-11-24 18:52 ` Linus Torvalds
2023-11-24 20:12 ` Linus Torvalds
2023-11-25 13:05 ` Christian Brauner
2023-11-25 13:10 ` Christian Brauner
2023-11-25 13:28 ` Omar Sandoval
2023-11-25 14:04 ` Christian Brauner
2023-11-24 18:26 ` pr-tracker-bot
2023-10-19 10:07 Christian Brauner
2023-10-19 16:37 ` Linus Torvalds
2023-10-20 11:14 ` Christian Brauner
2023-10-19 18:36 ` pr-tracker-bot
2023-09-26 10:39 Christian Brauner
2023-09-26 16:14 ` pr-tracker-bot
2023-07-06 11:52 Christian Brauner
2023-07-07 2:27 ` pr-tracker-bot
2023-07-02 11:28 Christian Brauner
2023-07-02 18:53 ` pr-tracker-bot
2023-05-25 12:22 Christian Brauner
2023-05-25 18:18 ` pr-tracker-bot
2023-05-12 15:31 Christian Brauner
2023-05-12 22:14 ` pr-tracker-bot
2023-04-03 11:04 Christian Brauner
2023-04-03 16:51 ` pr-tracker-bot
2023-03-12 12:18 Christian Brauner
2023-03-12 16:20 ` pr-tracker-bot
2020-09-22 21:29 [git pull] " Al Viro
2020-09-22 22:15 ` pr-tracker-bot
[not found] <CAHk-=wgdsv1UA+QtgiJM8KQAG7N7_9iK_edchnzZYyj+nxmfLA@mail.gmail.com>
[not found] ` <20200113195448.GT8904@ZenIV.linux.org.uk>
[not found] ` <CAHk-=whn5qk-e-KnYr6HNe5hp45v+XyDbsA2+szXvK3gC06A2w@mail.gmail.com>
2020-01-15 6:41 ` Al Viro
2020-01-15 19:35 ` pr-tracker-bot
2018-07-01 12:31 Al Viro
2018-07-01 19:36 ` Linus Torvalds
2018-07-01 20:05 ` Al Viro
2018-07-01 20:25 ` Linus Torvalds
2018-04-20 15:58 Al Viro
2018-04-20 18:29 ` Andrew Morton
2018-04-20 19:09 ` Al Viro
2018-04-20 19:57 ` Andrew Morton
2017-06-17 2:56 Al Viro
2017-04-09 5:40 Al Viro
2017-04-11 6:10 ` Linus Torvalds
2017-04-11 6:48 ` Al Viro
2017-04-11 21:02 ` Andreas Dilger
2017-04-12 7:00 ` Linus Torvalds
2017-04-15 6:41 ` Vegard Nossum
2017-04-15 16:51 ` Linus Torvalds
2017-04-15 17:08 ` Al Viro
2016-06-17 20:50 Q. hlist_bl_add_head_rcu() in d_alloc_parallel() J. R. Okajima
2016-06-17 22:16 ` Al Viro
2016-06-19 5:24 ` J. R. Okajima
2016-06-19 16:55 ` Al Viro
2016-06-20 4:34 ` J. R. Okajima
2016-06-20 5:35 ` Al Viro
2016-06-20 14:51 ` Al Viro
2016-06-20 17:14 ` [git pull] vfs fixes Al Viro
2016-06-08 2:12 Al Viro
2016-05-28 0:10 Al Viro
2016-02-28 1:09 Al Viro
2014-09-14 19:47 Al Viro
2014-09-26 20:38 ` Joachim Eastwood
2014-09-26 20:46 ` Joachim Eastwood
2014-09-26 20:58 ` Al Viro
2014-09-26 21:28 ` Joachim Eastwood
2014-09-26 21:52 ` Joachim Eastwood
2014-03-24 22:58 Imre Deak
2014-03-25 7:21 ` Sedat Dilek
2014-03-23 7:16 Al Viro
2014-03-23 10:57 ` Sedat Dilek
2014-03-23 15:35 ` Al Viro
2014-03-23 16:56 ` Al Viro
2014-03-23 16:36 ` Linus Torvalds
2014-03-23 16:45 ` Al Viro
2014-03-23 17:01 ` Linus Torvalds
2014-03-24 8:52 ` Sedat Dilek
2014-03-25 0:46 ` Linus Torvalds
2014-03-26 16:36 ` Sedat Dilek
2014-03-26 20:55 ` Linus Torvalds
2014-03-27 6:14 ` Sedat Dilek
2014-03-30 20:33 ` Al Viro
2014-03-30 20:55 ` Al Viro
2014-03-30 22:39 ` Linus Torvalds
2014-03-30 23:21 ` Al Viro
2013-06-22 7:16 Al Viro
2013-03-27 0:36 Al Viro
2012-03-10 21:30 Al Viro
2012-03-10 21:49 ` Linus Torvalds
2012-03-10 22:14 ` Al Viro
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