Commit ee8a1a8b authored Jan 20, 2015 by Peng Tao Committed by Trond Myklebust Jan 21, 2015

nfs: fix dio deadlock when O_DIRECT flag is flipped



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 <tao.peng@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

parent ec6f34e5

fs/nfs/direct.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -212,6 +212,12 @@ static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq,
		*/
		ssize_t nfs_direct_IO(int rw, struct kiocb iocb, struct iov_iter iter, loff_t pos)
		{
		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 (%pD) off/no(%Ld/%lu) EINVAL\n",
		iocb->ki_filp, (long long) pos, iter->nr_segs);

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