9p: Add a Direct IO support for non-cached operations.

The presence of v9fs_direct_IO() in the address space ops vector allowes open() O_DIRECT flags which would have failed otherwise. In the non-cached mode, we shunt off direct read and write requests before the VFS gets them, so this method should never be called. Direct IO is not 'yet' supported in the cached mode. Hence when this routine is called through generic_file_aio_read(), the read/write fails with an error. Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

9p: Add a Direct IO support for non-cached operations.
The presence of v9fs_direct_IO() in the address space ops vector allowes open() O_DIRECT flags which would have failed otherwise. In the non-cached mode, we shunt off direct read and write requests before the VFS gets them, so this method should never be called. Direct IO is not 'yet' supported in the cached mode. Hence when this routine is called through generic_file_aio_read(), the read/write fails with an error. Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
jvrao · Eric Van Hensbergen
1 parent 4f7ebe8072
Showing 1 changed file with 30 additions and 0 deletions Side-by-side Diff
fs/9p/vfs_addr.c
@@ -154,11 +154,41 @@
 	return 0;
 }
  
+/**
+ * v9fs_direct_IO - 9P address space operation for direct I/O
+ * @rw: direction (read or write)
+ * @iocb: target I/O control block
+ * @iov: array of vectors that define I/O buffer
+ * @pos: offset in file to begin the operation
+ * @nr_segs: size of iovec array
+ *
+ * The presence of v9fs_direct_IO() in the address space ops vector
+ * allowes open() O_DIRECT flags which would have failed otherwise.
+ *
+ * In the non-cached mode, we shunt off direct read and write requests before
+ * the VFS gets them, so this method should never be called.
+ *
+ * Direct IO is not 'yet' supported in the cached mode. Hence when
+ * this routine is called through generic_file_aio_read(), the read/write fails
+ * with an error.
+ *
+ */
+ssize_t v9fs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+		loff_t pos, unsigned long nr_segs)
+{
+	P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
+			"off/no(%lld/%lu) EINVAL\n",
+			iocb->ki_filp->f_path.dentry->d_name.name,
+			(long long) pos, nr_segs);
+
+	return -EINVAL;
+}
 const struct address_space_operations v9fs_addr_operations = {
       .readpage = v9fs_vfs_readpage,
       .readpages = v9fs_vfs_readpages,
       .releasepage = v9fs_release_page,
       .invalidatepage = v9fs_invalidate_page,
       .launder_page = v9fs_launder_page,
+      .direct_IO = v9fs_direct_IO,
 };
...	...	@@ -154,11 +154,41 @@
154	154	return 0;
155	155	}
156	156
	157	+/**
	158	+ * v9fs_direct_IO - 9P address space operation for direct I/O
	159	+ * @rw: direction (read or write)
	160	+ * @iocb: target I/O control block
	161	+ * @iov: array of vectors that define I/O buffer
	162	+ * @pos: offset in file to begin the operation
	163	+ * @nr_segs: size of iovec array
	164	+ *
	165	+ * The presence of v9fs_direct_IO() in the address space ops vector
	166	+ * allowes open() O_DIRECT flags which would have failed otherwise.
	167	+ *
	168	+ * In the non-cached mode, we shunt off direct read and write requests before
	169	+ * the VFS gets them, so this method should never be called.
	170	+ *
	171	+ * Direct IO is not 'yet' supported in the cached mode. Hence when
	172	+ * this routine is called through generic_file_aio_read(), the read/write fails
	173	+ * with an error.
	174	+ *
	175	+ */
	176	+ssize_t v9fs_direct_IO(int rw, struct kiocb iocb, const struct iovec iov,
	177	+ loff_t pos, unsigned long nr_segs)
	178	+{
	179	+ P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
	180	+ "off/no(%lld/%lu) EINVAL\n",
	181	+ iocb->ki_filp->f_path.dentry->d_name.name,
	182	+ (long long) pos, nr_segs);
	183	+
	184	+ return -EINVAL;
	185	+}
157	186	const struct address_space_operations v9fs_addr_operations = {
158	187	.readpage = v9fs_vfs_readpage,
159	188	.readpages = v9fs_vfs_readpages,
160	189	.releasepage = v9fs_release_page,
161	190	.invalidatepage = v9fs_invalidate_page,
162	191	.launder_page = v9fs_launder_page,
	192	+ .direct_IO = v9fs_direct_IO,
163	193	};