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Commit 7d6fec45 authored by Al Viro's avatar Al Viro
Browse files

vfs: start hiding vfsmount guts series 



Almost all fields of struct vfsmount are used only by core VFS (and
a fairly small part of it, at that).  The plan: embed struct vfsmount
into struct mount, making the latter visible only to core parts of VFS.
Then move fields from vfsmount to mount, eventually leaving only
mnt_root/mnt_sb/mnt_flags in struct vfsmount.  Filesystem code still
gets pointers to struct vfsmount and remains unchanged; all such
pointers go to struct vfsmount embedded into the instances of struct
mount allocated by fs/namespace.c.  When fs/namespace.c et.al. get
a pointer to vfsmount, they turn it into pointer to mount (using
container_of) and work with that.

This is the first part of series; struct mount is introduced,
allocation switched to using it.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent dabe0dc1

fs/mount.h

+9 −0
Original line number Diff line number Diff line 
#include <linux/mount.h>



struct mount {

	struct vfsmount mnt;

};



static inline struct mount *real_mount(struct vfsmount *mnt)

{

	return container_of(mnt, struct mount, mnt);

}



static inline int mnt_has_parent(struct vfsmount *mnt)

{

	return mnt != mnt->mnt_parent;

fs/namespace.c

+10 −8
Original line number Diff line number Diff line
@@ -173,8 +173,9 @@ unsigned int mnt_get_count(struct vfsmount *mnt) 


static struct vfsmount *alloc_vfsmnt(const char *name)

{

	struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);

	if (mnt) {

	struct mount *p = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);

	if (p) {

		struct vfsmount *mnt = &p->mnt;

		int err;



		err = mnt_alloc_id(mnt);
@@ -210,16 +211,16 @@ static struct vfsmount *alloc_vfsmnt(const char *name) 
		INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);

#endif

	}

	return mnt;

	return &p->mnt;



#ifdef CONFIG_SMP

out_free_devname:

	kfree(mnt->mnt_devname);

	kfree(p->mnt.mnt_devname);

#endif

out_free_id:

	mnt_free_id(mnt);

	mnt_free_id(&p->mnt);

out_free_cache:

	kmem_cache_free(mnt_cache, mnt);

	kmem_cache_free(mnt_cache, p);

	return NULL;

}
@@ -449,12 +450,13 @@ static void __mnt_unmake_readonly(struct vfsmount *mnt) 


static void free_vfsmnt(struct vfsmount *mnt)

{

	struct mount *p = real_mount(mnt);

	kfree(mnt->mnt_devname);

	mnt_free_id(mnt);

#ifdef CONFIG_SMP

	free_percpu(mnt->mnt_pcp);

#endif

	kmem_cache_free(mnt_cache, mnt);

	kmem_cache_free(mnt_cache, p);

}



/*
@@ -2698,7 +2700,7 @@ void __init mnt_init(void) 


	init_rwsem(&namespace_sem);



	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),

	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),

			0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);



	mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);