intrinsic automount and mountpoint degradation support

PATCH New David Howells 1 participant 1 message Jun 30, 2004 VFS

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David Howells

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2004-06-30 19:36 UTC #0 lore raw

PATCH 1/1 intrinsic automount and mountpoint degradation support

Hi Linus, Andrew,

Here's a patch that I worked out with Al Viro that adds support for a filesystem (such as kAFS) to perform automounting intrinsically without the need for a userspace daemon. It also adds support for such mountpoints to be degraded at the filesystem's behest until they've been untouched long enough that they'll be removed.

I've a patch (to follow) that removes some #ifdef's from fs/afs/* thus allowing it to make use of this facility.

David

fs/namei.c +6 -0

diff -uNr linux-2.6.7/fs/namei.c linux-2.6.7-auto/fs/namei.c
@@ -278,6 +278,12 @@
 	mntput(nd->mnt);
 }
 
+void path_release_on_umount(struct nameidata *nd)
+{
+	dput(nd->dentry);
+	_mntput(nd->mnt);
+}
+
 /*
  * Internal lookup() using the new generic dcache.
  * SMP-safe

fs/namespace.c +149 ~~-19~~

275 lines not on this page · raw message

fs/super.c +3 -0

diff -uNr linux-2.6.7/fs/super.c linux-2.6.7-auto/fs/super.c
@@ -788,6 +788,7 @@
 	mnt->mnt_root = dget(sb->s_root);
 	mnt->mnt_mountpoint = sb->s_root;
 	mnt->mnt_parent = mnt;
+	mnt->mnt_namespace = current->namespace;
 	up_write(&sb->s_umount);
 	put_filesystem(type);
 	return mnt;

@@ -804,6 +805,8 @@
 	return (struct vfsmount *)sb;
 }
 
+EXPORT_SYMBOL_GPL(do_kern_mount);
+
 struct vfsmount *kern_mount(struct file_system_type *type)
 {
 	return do_kern_mount(type->name, 0, type->name, NULL);

include/linux/fs.h +1 -0

diff -uNr linux-2.6.7/include/linux/fs.h linux-2.6.7-auto/include/linux/fs.h
@@ -714,6 +714,7 @@
 
 #define MNT_FORCE	0x00000001	/* Attempt to forcibily umount */
 #define MNT_DETACH	0x00000002	/* Just detach from the tree */
+#define MNT_EXPIRE	0x00000004	/* Mark for expiry */
 
 extern struct list_head super_blocks;
 extern spinlock_t sb_lock;

include/linux/mount.h +20 -1

diff -uNr linux-2.6.7/include/linux/mount.h linux-2.6.7-auto/include/linux/mount.h
@@ -29,8 +29,11 @@
 	struct list_head mnt_child;	/* and going through their mnt_child */
 	atomic_t mnt_count;
 	int mnt_flags;
+	int mnt_expiry_mark;		/* true if marked for expiry */
 	char *mnt_devname;		/* Name of device e.g. /dev/dsk/hda1 */
 	struct list_head mnt_list;
+	struct list_head mnt_fslink;	/* link in fs-specific expiry list */
+	struct namespace *mnt_namespace; /* containing namespace */
 };
 
 static inline struct vfsmount *mntget(struct vfsmount *mnt)

@@ -42,7 +45,7 @@
 
 extern void __mntput(struct vfsmount *mnt);
 
-static inline void mntput(struct vfsmount *mnt)
+static inline void _mntput(struct vfsmount *mnt)
 {
 	if (mnt) {
 		if (atomic_dec_and_test(&mnt->mnt_count))

@@ -50,10 +53,26 @@
 	}
 }
 
+static inline void mntput(struct vfsmount *mnt)
+{
+	if (mnt) {
+		mnt->mnt_expiry_mark = 0;
+		_mntput(mnt);
+	}
+}
+
 extern void free_vfsmnt(struct vfsmount *mnt);
 extern struct vfsmount *alloc_vfsmnt(const char *name);
 extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
 				      const char *name, void *data);
+
+struct nameidata;
+
+extern int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
+			int mnt_flags, struct list_head *fslist);
+
+extern void mark_mounts_for_expiry(struct list_head *mounts);
+
 extern spinlock_t vfsmount_lock;
 
 #endif

include/linux/namei.h +1 -0

diff -uNr linux-2.6.7/include/linux/namei.h linux-2.6.7-auto/include/linux/namei.h
@@ -57,6 +57,7 @@
 extern int FASTCALL(path_walk(const char *, struct nameidata *));
 extern int FASTCALL(link_path_walk(const char *, struct nameidata *));
 extern void path_release(struct nameidata *);
+extern void path_release_on_umount(struct nameidata *);
 
 extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry * lookup_hash(struct qstr *, struct dentry *);

include/linux/namespace.h +1 -1

diff -uNr linux-2.6.7/include/linux/namespace.h linux-2.6.7-auto/include/linux/namespace.h
@@ -14,7 +14,7 @@
 
 extern void umount_tree(struct vfsmount *);
 extern int copy_namespace(int, struct task_struct *);
-void __put_namespace(struct namespace *namespace);
+extern void __put_namespace(struct namespace *namespace);
 
 static inline void put_namespace(struct namespace *namespace)
 {