From: Jamie Lokier <jamie@shareable.org>
To: "Joseph D. Wagner" <theman@josephdwagner.info>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
"'Matthew Wilcox'" <willy@debian.org>
Subject: Re: [PATCH] fs/locks.c fcntl_setlease did not check if a file was opened for writing before granting a read lease
Date: Thu, 27 Nov 2003 16:50:43 +0000 [thread overview]
Message-ID: <20031127165043.GA19669@mail.shareable.org> (raw)
In-Reply-To: <000301c3b504$689afbf0$0201a8c0@joe>
Joseph D. Wagner wrote:
> But I THINK this is how a patch would fix the problem, in theory.
Sorry, it won't.
> + if ((arg == F_RDLCK)
> + && ((dentry->d_flags & O_WRONLY)
> + || (dentry->d_flags & O_RDWR)
> + || (dentry->d_flags & O_CREAT)
> + || (dentry->d_flags & O_TRUNC)
> + || (inode->i_flags & O_WRONLY)
> + || (inode->i_flags & O_RDWR)
> + || (inode->i_flags & O_CREAT)
> + || (inode->i_flags & O_TRUNC)))
> + goto out_unlock;
dentry->d_flags is a combination of the S_ flags, not O_ flags.
E.g. S_SYNC, S_NOATIME etc.
inode->i_flags is a combination of the DCACHE_ flags.
E.g. DCACHE_AUTOFS_PENDING, DCACHE_REFERENCED tc.
To detect if anyone has the file open for writing, you'll a new count
field which keeps track of writer references. Something like this:
if ((arg == F_RDLCK)
&& ((atomic_read(&inode->i_writer_count) != 0)))
You'll also need to modify all the places where that needs to be
maintained.
Btw, I'm not sure why the F_WRLCK case needs to check d_count and
i_count. Isn't it enough to check d_count? Won't all opens reference
the inode through a dentry?:
> if ((arg == F_WRLCK)
> && ((atomic_read(&dentry->d_count) > 1)
> || (atomic_read(&inode->i_count) > 1)))
-- Jamie
next prev parent reply other threads:[~2003-11-27 16:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-27 16:35 [PATCH] fs/locks.c fcntl_setlease did not check if a file was opened for writing before granting a read lease Joseph D. Wagner
2003-11-27 16:50 ` Jamie Lokier [this message]
2003-11-27 17:45 ` Nikita Danilov
2003-11-27 18:03 ` Jamie Lokier
2003-11-27 8:49 ` Joseph D. Wagner
2003-11-28 1:15 ` Jamie Lokier
2003-12-02 10:53 ` Sean Neakums
2003-12-03 2:02 ` Jamie Lokier
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