Eric Lee / smarc-ti-linux-kernel

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Commit 1066a175c7ef86259ea07f796c9a66dd26f28f5f

Authored by Peng Tao
Committed by Greg Kroah-Hartman
1 parent 907fe767f3
Exists in smarc-ti-linux-3.14.y and in 1 other branch processor-sdk-linux-01.00.00

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 <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 6 additions and 0 deletions Side-by-side Diff

... ... @@ -123,6 +123,12 @@
123 123 */
124 124 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
125 125 {
  126 + struct inode *inode = iocb->ki_filp->f_mapping->host;
  127 +
  128 + /* we only support swap file calling nfs_direct_IO */
  129 + if (!IS_SWAPFILE(inode))
  130 + return 0;
  131 +
126 132 #ifndef CONFIG_NFS_SWAP
127 133 dprintk("NFS: nfs_direct_IO (%pD) off/no(%Ld/%lu) EINVAL\n",
128 134 iocb->ki_filp, (long long) pos, nr_segs);