From: Peng Tao Date: Mon, 19 Jan 2015 23:44:29 +0000 (+0800) Subject: nfs: fix dio deadlock when O_DIRECT flag is flipped X-Git-Tag: v3.12.38~82 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=88bc02271ea706c54abf4237744436c5982d09bf;p=thirdparty%2Fkernel%2Fstable.git nfs: fix dio deadlock when O_DIRECT flag is flipped commit ee8a1a8b160a87dc3a9c81a86796aa4db85ea815 upstream. We only support swap file calling nfs_direct_IO. However, application might be able to get to nfs_direct_IO if it toggles O_DIRECT flag during IO and it can deadlock because we grab inode->i_mutex in nfs_file_direct_write(). So return 0 for such case. Then the generic layer will fall back to buffer IO. Signed-off-by: Peng Tao Signed-off-by: Trond Myklebust Signed-off-by: Jiri Slaby --- diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index d751a2383c24e..db6245c1cd33e 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -123,6 +123,12 @@ static inline int put_dreq(struct nfs_direct_req *dreq) */ ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs) { + struct inode *inode = iocb->ki_filp->f_mapping->host; + + /* we only support swap file calling nfs_direct_IO */ + if (!IS_SWAPFILE(inode)) + return 0; + #ifndef CONFIG_NFS_SWAP dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n", iocb->ki_filp->f_path.dentry->d_name.name,