From 42e49608683ab25fbbbf9c40edb944601e543882 Mon Sep 17 00:00:00 2001
From: Wu Fengguang <fengguang.wu@intel.com>
Date: Fri, 5 Mar 2010 13:42:01 -0800
Subject: [PATCH] vfs: take f_lock on modifying f_mode after open time
We'll introduce FMODE_RANDOM which will be runtime modified. So protect
all runtime modification to f_mode with f_lock to avoid races.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: <stable@kernel.org> [2.6.33.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/file_table.c | 2 ++
fs/nfsd/nfs4state.c | 2 ++
2 files changed, 4 insertions(+)
diff --git a/fs/file_table.c b/fs/file_table.c
index b98404b54383..32d12b78bac8 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -393,7 +393,9 @@ retry:
continue;
if (!(f->f_mode & FMODE_WRITE))
continue;
+ spin_lock(&f->f_lock);
f->f_mode &= ~FMODE_WRITE;
+ spin_unlock(&f->f_lock);
if (file_check_writeable(f) != 0)
continue;
file_release_write(f);
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f19ed866c95f..fcafe6087f69 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1998,7 +1998,9 @@ nfs4_file_downgrade(struct file *filp, unsigned int share_access)
{
if (share_access & NFS4_SHARE_ACCESS_WRITE) {
drop_file_write_access(filp);
+ spin_lock(&filp->f_lock);
filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;
+ spin_unlock(&filp->f_lock);
}
}