[PATCH] kill lookup_vfsmnt()

[Christoph Hellwig <hch@xxxxxxxxxx>]

Hi,

the lookup_vfsmnt function in the xfs tree is broken by design
as it tries to get a struct vfsmnt for a given kdev_t but a
filesystem can be mounted at multiple mount points in Linux 2.4
and so the mapping is not unique.

The actual usage of the function is not broken as it is used only
to get the struct super_block from the vfsmnt which is again
unique for a kdev_t (but doesn't have to - I know of at least one
fs design where there might be multiple sb's for a dev).

Suggestion: kill lookup_vfsmnt and use get_super instead.
Patch attached.

        Christoph

-- 
Of course it doesn't work. We've performed a software upgrade.


Index: fs/super.c
===================================================================
RCS file: /cvs/linux-2.4-xfs/linux/fs/super.c,v
retrieving revision 1.42
diff -u -b -B -r1.42 super.c
--- fs/super.c  2001/02/22 21:09:04     1.42
+++ fs/super.c  2001/03/03 18:29:44
@@ -456,24 +456,6 @@
         return sp - buf;       /* no trailing NUL */
 }
 
-struct vfsmount *lookup_vfsmnt(kdev_t dev)
-{
-       struct list_head *p;
-
-       if (list_empty(&vfsmntlist))
-               return NULL;
-
-       for (p = vfsmntlist.next; p != &vfsmntlist; p = p->next) {
-               struct vfsmount *tmp = list_entry(p, struct vfsmount, mnt_list);
-               if (tmp->mnt_sb->s_dev == dev) {
-                       return (tmp);
-               }
-       }
-
-       return NULL;
-}
-
-
 static struct proc_fs_info {
        int flag;
        char *str;
Index: fs/xfs/linux/xfs_vfs.c
===================================================================
RCS file: /cvs/linux-2.4-xfs/linux/fs/xfs/linux/xfs_vfs.c,v
retrieving revision 1.21
diff -u -b -B -r1.21 xfs_vfs.c
--- fs/xfs/linux/xfs_vfs.c      2000/11/22 06:53:25     1.21
+++ fs/xfs/linux/xfs_vfs.c      2001/03/03 18:30:20
@@ -211,14 +211,16 @@
        long s;
        struct vfs *vfsp;
        kdev_t  kdev = MKDEV(MAJOR(dev), MINOR(dev));
-       struct vfsmount *entry;
+       struct super_block *sb;
 
        lock_kernel();
-       entry = lookup_vfsmnt(kdev);
-
+       sb = get_super(kdev);
        unlock_kernel();
-       if (entry) {
-               vfsp = LINVFS_GET_VFS(entry->mnt_sb);
+
+       if (!sb)
+               return NULL;
+       
+       vfsp = LINVFS_GET_VFS(sb);
 again:
                spin_lock_irqsave(&vfslock, s);
                if (vfsp->vfs_dev == dev &&
@@ -241,9 +243,6 @@
                }
                spin_unlock_irqrestore(&vfslock, s);
                return vfsp;
-       } else {
-               return NULL;
-       }
 }
 
 void
@@ -312,14 +311,13 @@
 {
         register struct vfs *vfsp;
        kdev_t  kdev = MKDEV(MAJOR(dev), MINOR(dev));
-       struct vfsmount *entry;
+       struct super_block *sb;
 
        lock_kernel();
-       entry = lookup_vfsmnt(kdev);
-
+       sb = get_super(kdev);
 
-        if (entry) {
-               vfsp = LINVFS_GET_VFS(entry->mnt_sb);
+       if (sb) {
+               vfsp = LINVFS_GET_VFS(sb);
                 if ((vfsp->vfs_dev == dev) &&
                     (fstype == VFS_FSTYPE_ANY || fstype == vfsp->vfs_fstype)) {
                        unlock_kernel();
Index: include/linux/mount.h
===================================================================
RCS file: /cvs/linux-2.4-xfs/linux/include/linux/mount.h,v
retrieving revision 1.12
diff -u -b -B -r1.12 mount.h
--- include/linux/mount.h       2000/10/23 18:56:35     1.12
+++ include/linux/mount.h       2001/03/03 18:30:35
@@ -38,7 +38,6 @@
                atomic_inc(&mnt->mnt_count);
        return mnt;
 }
-struct vfsmount *lookup_vfsmnt(kdev_t dev);
 
 static inline void mntput(struct vfsmount *mnt)
 {
Index: kernel/ksyms.c
===================================================================
RCS file: /cvs/linux-2.4-xfs/linux/kernel/ksyms.c,v
retrieving revision 1.80
diff -u -b -B -r1.80 ksyms.c
--- kernel/ksyms.c      2001/03/01 21:13:39     1.80
+++ kernel/ksyms.c      2001/03/03 18:30:40
@@ -143,7 +143,6 @@
 EXPORT_SYMBOL(get_fs_type);
 EXPORT_SYMBOL(get_super);
 EXPORT_SYMBOL(get_empty_super);
-EXPORT_SYMBOL(lookup_vfsmnt);
 EXPORT_SYMBOL(getname);
 EXPORT_SYMBOL(names_cachep);
 EXPORT_SYMBOL(fput);