Linux 3.11 compat: fops->iterate()

Commit torvalds/linux@2233f31aade393641f0eaed43a71110e629bb900
replaced ->readdir() with ->iterate() in struct file_operations.
All filesystems must now use the new ->iterate method.

To handle this the code was reworked to use the new ->iterate
interface.  Care was taken to keep the majority of changes
confined to the ZPL layer which is already Linux specific.
However, minor changes were required to the common zfs_readdir()
function.

Compatibility with older kernels was accomplished by adding
versions of the trivial dir_emit* helper functions.  Also the
various *_readdir() functions were reworked in to wrappers
which create a dir_context structure to pass to the new
*_iterate() functions.

Unfortunately, the new dir_emit* functions prevent us from
passing a private pointer to the filldir function.  The xattr
directory code leveraged this ability through zfs_readdir()
to generate the list of xattr names.  Since we can no longer
use zfs_readdir() a simplified zpl_xattr_readdir() function
was added to perform the same task.

Signed-off-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1653
Issue #1591

1 files changed, 43 insertions, 0 deletions

diff --git a/config/kernel-vfs-iterate.m4 b/config/kernel-vfs-iterate.m4
new file mode 100644
index 000000000..c2c65622c
--- /dev/null
+++ b/config/kernel-vfs-iterate.m4
@@ -0,0 +1,43 @@
+dnl #
+dnl # 3.11 API change
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_VFS_ITERATE], [
+	AC_MSG_CHECKING([whether fops->iterate() is available])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+		int iterate(struct file *filp, struct dir_context * context)
+		    { return 0; }
+
+		static const struct file_operations fops
+		    __attribute__ ((unused)) = {
+			.iterate	 = iterate,
+		};
+	],[
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_VFS_ITERATE, 1,
+		          [fops->iterate() is available])
+	],[
+		AC_MSG_RESULT(no)
+
+		AC_MSG_CHECKING([whether fops->readdir() is available])
+		ZFS_LINUX_TRY_COMPILE([
+			#include <linux/fs.h>
+			int readdir(struct file *filp, void *entry, filldir_t func)
+			    { return 0; }
+
+			static const struct file_operations fops
+			    __attribute__ ((unused)) = {
+				.readdir = readdir,
+			};
+		],[
+		],[
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_VFS_READDIR, 1,
+				  [fops->readdir() is available])
+		],[
+			AC_MSG_ERROR(no; file a bug report with ZFSOnLinux)
+		])
+
+	])
+])