Linux 4.12 compat: super_setup_bdi_name()

All filesystems were converted to dynamically allocated BDIs.  The
destruction of backing_dev_info structures is handled as part of
super block destruction.  Refactor the code to abstract away the
details of creating and destroying a BDI.

Reviewed-by: Chunwei Chen <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #6089 

2 files changed, 78 insertions, 10 deletions

diff --git a/include/linux/vfs_compat.h b/include/linux/vfs_compat.h
index cd22b522a..4e61b1d09 100644
--- a/include/linux/vfs_compat.h
+++ b/include/linux/vfs_compat.h
@@ -70,45 +70,114 @@ truncate_setsize(struct inode *ip, loff_t new)
 /*
  * 2.6.32 - 2.6.33, bdi_setup_and_register() is not available.
  * 2.6.34 - 3.19, bdi_setup_and_register() takes 3 arguments.
- * 4.0 - x.y, bdi_setup_and_register() takes 2 arguments.
+ * 4.0 - 4.11, bdi_setup_and_register() takes 2 arguments.
+ * 4.12 - x.y, super_setup_bdi_name() new interface.
  */
-#if defined(HAVE_2ARGS_BDI_SETUP_AND_REGISTER)
+#if defined(HAVE_SUPER_SETUP_BDI_NAME)
 static inline int
-zpl_bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
+zpl_bdi_setup(struct super_block *sb, char *name)
 {
-	return (bdi_setup_and_register(bdi, name));
+	return (super_setup_bdi_name(sb, name));
+}
+static inline void
+zpl_bdi_destroy(struct super_block *sb)
+{
+}
+#elif defined(HAVE_2ARGS_BDI_SETUP_AND_REGISTER)
+static inline int
+zpl_bdi_setup(struct super_block *sb, char *name)
+{
+	struct backing_dev_info *bdi;
+	int error;
+
+	bdi = kmem_zalloc(sizeof (struct backing_dev_info), KM_SLEEP);
+	error = bdi_setup_and_register(bdi, name);
+	if (error) {
+		kmem_free(bdi, sizeof (struct backing_dev_info));
+		return (error);
+	}
+
+	sb->s_bdi = bdi;
+
+	return (0);
+}
+static inline void
+zpl_bdi_destroy(struct super_block *sb)
+{
+	struct backing_dev_info *bdi = sb->s_bdi;
+
+	bdi_destroy(bdi);
+	kmem_free(bdi, sizeof (struct backing_dev_info));
+	sb->s_bdi = NULL;
 }
 #elif defined(HAVE_3ARGS_BDI_SETUP_AND_REGISTER)
 static inline int
-zpl_bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
+zpl_bdi_setup(struct super_block *sb, char *name)
 {
-	return (bdi_setup_and_register(bdi, name, BDI_CAP_MAP_COPY));
+	struct backing_dev_info *bdi;
+	int error;
+
+	bdi = kmem_zalloc(sizeof (struct backing_dev_info), KM_SLEEP);
+	error = bdi_setup_and_register(bdi, name, BDI_CAP_MAP_COPY);
+	if (error) {
+		kmem_free(sb->s_bdi, sizeof (struct backing_dev_info));
+		return (error);
+	}
+
+	sb->s_bdi = bdi;
+
+	return (0);
+}
+static inline void
+zpl_bdi_destroy(struct super_block *sb)
+{
+	struct backing_dev_info *bdi = sb->s_bdi;
+
+	bdi_destroy(bdi);
+	kmem_free(bdi, sizeof (struct backing_dev_info));
+	sb->s_bdi = NULL;
 }
 #else
 extern atomic_long_t zfs_bdi_seq;
 
 static inline int
-zpl_bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
+zpl_bdi_setup(struct super_block *sb, char *name)
 {
+	struct backing_dev_info *bdi;
 	char tmp[32];
 	int error;
 
+	bdi = kmem_zalloc(sizeof (struct backing_dev_info), KM_SLEEP);
 	bdi->name = name;
 	bdi->capabilities = BDI_CAP_MAP_COPY;
 
 	error = bdi_init(bdi);
-	if (error)
+	if (error) {
+		kmem_free(bdi, sizeof (struct backing_dev_info));
 		return (error);
+	}
 
 	sprintf(tmp, "%.28s%s", name, "-%d");
 	error = bdi_register(bdi, NULL, tmp,
 	    atomic_long_inc_return(&zfs_bdi_seq));
 	if (error) {
 		bdi_destroy(bdi);
+		kmem_free(bdi, sizeof (struct backing_dev_info));
 		return (error);
 	}
 
-	return (error);
+	sb->s_bdi = bdi;
+
+	return (0);
+}
+static inline void
+zpl_bdi_destroy(struct super_block *sb)
+{
+	struct backing_dev_info *bdi = sb->s_bdi;
+
+	bdi_destroy(bdi);
+	kmem_free(bdi, sizeof (struct backing_dev_info));
+	sb->s_bdi = NULL;
 }
 #endif
 
diff --git a/include/sys/zfs_vfsops.h b/include/sys/zfs_vfsops.h
index aeecc472d..2326da422 100644
--- a/include/sys/zfs_vfsops.h
+++ b/include/sys/zfs_vfsops.h
@@ -75,7 +75,6 @@ typedef struct zfs_mnt {
 struct zfsvfs {
 	vfs_t		*z_vfs;		/* generic fs struct */
 	struct super_block *z_sb;	/* generic super_block */
-	struct backing_dev_info z_bdi;	/* generic backing dev info */
 	struct zfsvfs	*z_parent;	/* parent fs */
 	objset_t	*z_os;		/* objset reference */
 	uint64_t	z_flags;	/* super_block flags */