[PATCH] namei fixes (17/19)

follow_mount() made void, reordered dput()/mntput() in it.

follow_dotdot() switched from struct vfmount ** + struct dentry ** to
struct nameidata *; callers updated.

Equivalent transformation + fix for too-early-mntput() race.

Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 19 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 444086d441e1..36925ff307b3 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -596,20 +596,17 @@ static int __follow_mount(struct path *path)
         return res;
 }
 
-static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
 {
-        int res = 0;
         while (d_mountpoint(*dentry)) {
                 struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
                 if (!mounted)
                         break;
+                dput(*dentry);
                 mntput(*mnt);
                 *mnt = mounted;
-                dput(*dentry);
                 *dentry = dget(mounted->mnt_root);
-                res = 1;
         }
-        return res;
 }
 
 /* no need for dcache_lock, as serialization is taken care in
@@ -630,41 +627,41 @@ int follow_down(struct vfsmount **mnt, struct dentry **dentry)
         return 0;
 }
 
-static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
+static inline void follow_dotdot(struct nameidata *nd)
 {
         while(1) {
                 struct vfsmount *parent;
-                struct dentry *old = *dentry;
+                struct dentry *old = nd->dentry;
 
                 read_lock(&current->fs->lock);
-                if (*dentry == current->fs->root &&
-                    *mnt == current->fs->rootmnt) {
+                if (nd->dentry == current->fs->root &&
+                    nd->mnt == current->fs->rootmnt) {
                         read_unlock(&current->fs->lock);
                         break;
                 }
                 read_unlock(&current->fs->lock);
                 spin_lock(&dcache_lock);
-                if (*dentry != (*mnt)->mnt_root) {
-                        *dentry = dget((*dentry)->d_parent);
+                if (nd->dentry != nd->mnt->mnt_root) {
+                        nd->dentry = dget(nd->dentry->d_parent);
                         spin_unlock(&dcache_lock);
                         dput(old);
                         break;
                 }
                 spin_unlock(&dcache_lock);
                 spin_lock(&vfsmount_lock);
-                parent = (*mnt)->mnt_parent;
-                if (parent == *mnt) {
+                parent = nd->mnt->mnt_parent;
+                if (parent == nd->mnt) {
                         spin_unlock(&vfsmount_lock);
                         break;
                 }
                 mntget(parent);
-                *dentry = dget((*mnt)->mnt_mountpoint);
+                nd->dentry = dget(nd->mnt->mnt_mountpoint);
                 spin_unlock(&vfsmount_lock);
                 dput(old);
-                mntput(*mnt);
-                *mnt = parent;
+                mntput(nd->mnt);
+                nd->mnt = parent;
         }
-        follow_mount(mnt, dentry);
+        follow_mount(&nd->mnt, &nd->dentry);
 }
 
 /*
@@ -772,7 +769,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
                         case 2: 
                                 if (this.name[1] != '.')
                                         break;
-                                follow_dotdot(&nd->mnt, &nd->dentry);
+                                follow_dotdot(nd);
                                 inode = nd->dentry->d_inode;
                                 /* fallthrough */
                         case 1:
@@ -839,7 +836,7 @@ last_component:
                         case 2: 
                                 if (this.name[1] != '.')
                                         break;
-                                follow_dotdot(&nd->mnt, &nd->dentry);
+                                follow_dotdot(nd);
                                 inode = nd->dentry->d_inode;
                                 /* fallthrough */
                         case 1: