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, 20 insertions, 3 deletions

diff --git a/module/zfs/zpl_file.c b/module/zfs/zpl_file.c
index 299589193..6598c1779 100644
--- a/module/zfs/zpl_file.c
+++ b/module/zfs/zpl_file.c
@@ -64,21 +64,34 @@ zpl_release(struct inode *ip, struct file *filp)
 }
 
 static int
-zpl_readdir(struct file *filp, void *dirent, filldir_t filldir)
+zpl_iterate(struct file *filp, struct dir_context *ctx)
 {
 	struct dentry *dentry = filp->f_path.dentry;
 	cred_t *cr = CRED();
 	int error;
 
 	crhold(cr);
-	error = -zfs_readdir(dentry->d_inode, dirent, filldir,
-	    &filp->f_pos, cr);
+	error = -zfs_readdir(dentry->d_inode, ctx, cr);
 	crfree(cr);
 	ASSERT3S(error, <=, 0);
 
 	return (error);
 }
 
+#if !defined(HAVE_VFS_ITERATE)
+static int
+zpl_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	struct dir_context ctx = DIR_CONTEXT_INIT(dirent, filldir, filp->f_pos);
+	int error;
+
+	error = zpl_iterate(filp, &ctx);
+	filp->f_pos = ctx.pos;
+
+	return (error);
+}
+#endif /* HAVE_VFS_ITERATE */
+
 #if defined(HAVE_FSYNC_WITH_DENTRY)
 /*
  * Linux 2.6.x - 2.6.34 API,
@@ -506,7 +519,11 @@ const struct file_operations zpl_file_operations = {
 const struct file_operations zpl_dir_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
+#ifdef HAVE_VFS_ITERATE
+	.iterate	= zpl_iterate,
+#else
 	.readdir	= zpl_readdir,
+#endif
 	.fsync		= zpl_fsync,
 	.unlocked_ioctl = zpl_ioctl,
 #ifdef CONFIG_COMPAT