[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>

diff --git a/fs/namei.c b/fs/namei.c
index 444086d..36925ff 100644 (file)
--- 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: