From: Al Viro <viro@ZenIV.linux.org.uk>
To: Matthew Wilcox <matthew@wil.cx>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Eric Paris <eparis@redhat.com>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, hch@infradead.org,
zohar@us.ibm.com, warthog9@kernel.org, david@fromorbit.com,
jmorris@namei.org, kyle@mcmartin.ca, hpa@zytor.com,
akpm@linux-foundation.org, mingo@elte.hu
Subject: Re: [PATCH 1/3] IMA: move read/write counters into struct inode
Date: Wed, 20 Oct 2010 04:15:04 +0100 [thread overview]
Message-ID: <20101020031504.GA18581@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20101019191133.GE2447@parisc-linux.org>
On Tue, Oct 19, 2010 at 01:11:33PM -0600, Matthew Wilcox wrote:
> Hm. Sounds like the same question that the file leases code needs
> answered. The important difference is that the leases code can just
> refuse to set a lease on inodes with multiple dentries.
>
> While my mind's on it ... Al, is this code even close to correct?
>
> if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
> goto out;
> if ((arg == F_WRLCK)
> && ((atomic_read(&dentry->d_count) > 1)
> || (atomic_read(&inode->i_count) > 1)))
> goto out;
No. This is complete junk; note that e.g. ls -lR will disrupt it, since
lstat(2) will bump dentry refcount. The first part is more or less OK;
the second makes no sense.
What is it trying to do? Note that the first part also doesn't make a lot
of sense, since you could be acquiring a write reference *right* *now*,
just as that check passes. And you could finish getting it before you get
to do anything else in generic_setlease().
next prev parent reply other threads:[~2010-10-20 3:15 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-19 1:16 [PATCH 1/3] IMA: move read/write counters into struct inode Eric Paris
2010-10-19 1:16 ` [PATCH 2/3] IMA: only allocate iint when needed Eric Paris
2010-10-19 1:17 ` [PATCH 3/3] IMA: use rbtree instead of radix tree for inode information cache Eric Paris
2010-10-19 1:30 ` [PATCH 1/3] IMA: move read/write counters into struct inode Christoph Hellwig
2010-10-19 2:14 ` Eric Paris
2010-10-19 7:39 ` Dave Chinner
2010-10-19 16:24 ` Eric Paris
2010-10-19 16:29 ` Christoph Hellwig
2010-10-19 8:39 ` Ingo Molnar
2010-10-19 2:46 ` Eric Paris
2010-10-19 15:52 ` Linus Torvalds
2010-10-19 16:36 ` Eric Paris
2010-10-19 16:55 ` Al Viro
2010-10-19 17:03 ` Linus Torvalds
2010-10-19 17:28 ` Al Viro
2010-10-19 18:16 ` Mimi Zohar
2010-10-20 13:10 ` John Stoffel
2010-10-20 13:36 ` Al Viro
2010-10-20 14:09 ` John Stoffel
2010-10-19 19:11 ` Matthew Wilcox
2010-10-20 3:15 ` Al Viro [this message]
2010-10-20 17:38 ` J. Bruce Fields
2010-10-19 22:49 ` Eric Paris
2010-10-20 14:38 ` Ingo Molnar
2010-10-20 14:46 ` Eric Paris
2010-10-20 15:15 ` Ingo Molnar
2010-10-20 15:25 ` Eric Paris
2010-10-21 16:15 ` Casey Schaufler
2010-10-22 8:48 ` Ingo Molnar
2010-10-22 17:50 ` Casey Schaufler
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