UPSTREAM: zsfold: Convert zsfold to use the new mount API

Convert the zsfold filesystem to the new internal mount API as the old one
will be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.

Change-Id: Ia3da9e9fd2ef5214c4e7fb71228f8b90c15f9e71
Signed-off-by: David Howells <dhowells@redhat.com>

include/uapi/linux/magic.h

@@ -94,5 +94,6 @@
 #define BALLOON_KVM_MAGIC	0x13661366
 #define ZSMALLOC_MAGIC		0x58295829
 #define DMA_BUF_MAGIC		0x444d4142	/* "DMAB" */
+#define Z3FOLD_MAGIC		0x33
 
 #endif /* __LINUX_MAGIC_H__ */

mm/z3fold.c

@@ -25,7 +25,6 @@
 #include <linux/atomic.h>
 #include <linux/sched.h>
 #include <linux/cpumask.h>
-#include <linux/dcache.h>
 #include <linux/list.h>
 #include <linux/mm.h>
 #include <linux/module.h>
@@ -35,12 +34,14 @@
 #include <linux/compaction.h>
 #include <linux/percpu.h>
 #include <linux/mount.h>
+#include <linux/pseudo_fs.h>
 #include <linux/fs.h>
 #include <linux/preempt.h>
 #include <linux/workqueue.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/zpool.h>
+#include <linux/magic.h>
 
 /*
  * NCHUNKS_ORDER determines the internal allocation granularity, effectively
@@ -239,15 +240,14 @@ static inline void free_handle(unsigned long handle)
 	}
 }
 
-static struct dentry *z3fold_do_mount(struct file_system_type *fs_type,
-				int flags, const char *dev_name, void *data)
+static int z3fold_init_fs_context(struct fs_context *fc)
 {
-	return mount_pseudo(fs_type, "z3fold:", NULL, NULL, 0x33);
+	return init_pseudo(fc, Z3FOLD_MAGIC) ? 0 : -ENOMEM;
 }
 
 static struct file_system_type z3fold_fs = {
 	.name		= "z3fold",
-	.mount		= z3fold_do_mount,
+	.init_fs_context = z3fold_init_fs_context,
 	.kill_sb	= kill_anon_super,
 };