[PATCH] final ->d_parent fixes

OK, here's ->d_parent stuff unrelated to printk.  Looking into printk
right now...

fs/ncpfs/dir.c

@@ -257,12 +257,18 @@ static int
 __ncp_lookup_validate(struct dentry * dentry, int flags)
 {
 	struct ncp_server *server;
-	struct inode *dir = dentry->d_parent->d_inode;
+	struct dentry *parent;
+	struct inode *dir;
 	struct ncp_entry_info finfo;
 	int res, val = 0, len = dentry->d_name.len + 1;
 	__u8 __name[len];
 
-	if (!dentry->d_inode || !dir)
+	read_lock(&dparent_lock);
+	parent = dget(dentry->d_parent);
+	read_unlock(&dparent_lock);
+	dir = parent->d_inode;
+
+	if (!dentry->d_inode)
 		goto finished;
 
 	server = NCP_SERVER(dir);
@@ -313,6 +319,7 @@ __ncp_lookup_validate(struct dentry * dentry, int flags)
 
 finished:
 	DDPRINTK("ncp_lookup_validate: result=%d\n", val);
+	dput(parent);
 	return val;
 }
 

fs/nfs/dir.c

@@ -467,12 +467,16 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
 {
 	struct inode *dir;
 	struct inode *inode;
+	struct dentry *parent;
 	int error;
 	struct nfs_fh fhandle;
 	struct nfs_fattr fattr;
 
+	read_lock(&dparent_lock);
+	parent = dget(dentry->d_parent);
+	read_unlock(&dparent_lock);
 	lock_kernel();
-	dir = dentry->d_parent->d_inode;
+	dir = parent->d_inode;
 	inode = dentry->d_inode;
 
 	if (!inode) {
@@ -508,6 +512,7 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
 	nfs_renew_times(dentry);
  out_valid:
 	unlock_kernel();
+	dput(parent);
 	return 1;
  out_bad:
 	NFS_CACHEINV(dir);
@@ -521,6 +526,7 @@ static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
 	}
 	d_drop(dentry);
 	unlock_kernel();
+	dput(parent);
 	return 0;
 }
 

fs/nfsd/export.c

@@ -112,11 +112,15 @@ exp_parent(svc_client *clp, struct super_block *sb, struct dentry *dentry)
 	struct list_head *head = &clp->cl_export[EXPORT_HASH(sb->s_dev)];
 	struct list_head *p;
 
+	spin_lock(&dcache_lock);
 	list_for_each(p, head) {
 		svc_export *exp = list_entry(p, svc_export, ex_hash);
-		if (is_subdir(dentry, exp->ex_dentry))
+		if (is_subdir(dentry, exp->ex_dentry)) {
+			spin_unlock(&dcache_lock);
 			return exp;
 		}
+	}
+	spin_unlock(&dcache_lock);
 	return NULL;
 }
 
@@ -132,12 +136,16 @@ exp_child(svc_client *clp, struct super_block *sb, struct dentry *dentry)
 	struct list_head *p;
 	struct dentry *ndentry;
 
+	spin_lock(&dcache_lock);
 	list_for_each(p, head) {
 		svc_export *exp = list_entry(p, svc_export, ex_hash);
 		ndentry = exp->ex_dentry;
-		if (ndentry && is_subdir(ndentry->d_parent, dentry))
+		if (ndentry && is_subdir(ndentry->d_parent, dentry)) {
+			spin_unlock(&dcache_lock);
 			return exp;
 		}
+	}
+	spin_unlock(&dcache_lock);
 	return NULL;
 }
 

fs/nfsd/nfs3xdr.c

@@ -699,10 +699,12 @@ encode_entry(struct readdir_cd *cd, const char *name,
 
 		fh_init(&fh, NFS3_FHSIZE);
 		if (isdotent(name, namlen)) {
-			dchild = dparent;
-			if (namlen == 2)
-				dchild = dchild->d_parent;
-			dchild = dget(dchild);
+			if (namlen == 2) {
+				read_lock(&dparent_lock);
+				dchild = dget(dparent->d_parent);
+				read_unlock(&dparent_lock);
+			} else
+				dchild = dget(dparent);
 		} else
 			dchild = lookup_one_len(name, dparent,namlen);
 		if (IS_ERR(dchild))

fs/nfsd/nfsfh.c

@@ -477,6 +477,11 @@ find_fh_dentry(struct super_block *sb, __u32 *datap, int len, int fhtype, int ne
 			/* Something wrong.  We need to drop the whole dentry->result path
 			 * whatever it was
 			 */
+			/*
+			 *  FIXME: the loop below will do Bad Things(tm) if
+			 *  dentry (or one of its ancestors) become attached
+			 *  to the tree (e.g. due to VFAT-style alias handling)
+			 */
 			struct dentry *d;
 			for (d=result ; d ; d=(d->d_parent == d)?NULL:d->d_parent)
 				d_drop(d);
@@ -610,7 +615,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 				dentry = dget(exp->ex_dentry);
 				break;
 			default:
-				dentry = find_fh_dentry(exp->ex_dentry->d_inode->i_sb,
+				dentry = find_fh_dentry(exp->ex_dentry->d_sb,
 							datap, data_left, fh->fh_fileid_type,
 							!(exp->ex_flags & NFSEXP_NOSUBTREECHECK));
 			}
@@ -619,7 +624,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 			tfh[0] = fh->ofh_ino;
 			tfh[1] = fh->ofh_generation;
 			tfh[2] = fh->ofh_dirino;
-			dentry = find_fh_dentry(exp->ex_dentry->d_inode->i_sb,
+			dentry = find_fh_dentry(exp->ex_dentry->d_sb,
 						tfh, 3, fh->ofh_dirino?2:1,
 						!(exp->ex_flags & NFSEXP_NOSUBTREECHECK));
 		}
@@ -676,11 +681,15 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 		if (exp->ex_dentry != dentry) {
 			struct dentry *tdentry = dentry;
 
+			spin_lock(&dcache_lock);
 			do {
 				tdentry = tdentry->d_parent;
 				if (exp->ex_dentry == tdentry)
 					break;
 				/* executable only by root and we can't be root */
+				/*
+				 * FIXME: permissions check is not that simple
+				 */
 				if (current->fsuid
 				    && (exp->ex_flags & NFSEXP_ROOTSQUASH)
 				    && !(tdentry->d_inode->i_uid
@@ -700,8 +709,10 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 				printk("nfsd Security: %s/%s bad export.\n",
 				       dentry->d_parent->d_name.name,
 				       dentry->d_name.name);
+				spin_unlock(&dcache_lock);
 				goto out;
 			}
+			spin_unlock(&dcache_lock);
 		}
 	}
 
@@ -729,7 +740,7 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 inline int _fh_update(struct dentry *dentry, struct svc_export *exp,
 		      __u32 *datap, int *maxsize)
 {
-	struct super_block *sb = dentry->d_inode->i_sb;
+	struct super_block *sb = dentry->d_sb;
 	
 	if (dentry == exp->ex_dentry) {
 		*maxsize = 0;
@@ -806,7 +817,7 @@ fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry, st
 
 	if (ref_fh &&
 	    ref_fh->fh_handle.fh_version == 0xca &&
-	    parent->d_inode->i_sb->s_op->dentry_to_fh == NULL) {
+	    dentry->d_sb->s_op->dentry_to_fh == NULL) {
 		/* old style filehandle please */
 		memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
 		fhp->fh_handle.fh_size = NFS_FHSIZE;

fs/nfsd/vfs.c

@@ -114,29 +114,33 @@ nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
 	if (isdotent(name, len)) {
 		if (len==1)
 			dentry = dget(dparent);
-		else if (dparent != exp->ex_dentry)
+		else if (dparent != exp->ex_dentry) {
+			read_lock(&dparent_lock);
 			dentry = dget(dparent->d_parent);
-		else  if (!EX_CROSSMNT(exp))
+			read_unlock(&dparent_lock);
+		} else  if (!EX_CROSSMNT(exp))
 			dentry = dget(dparent); /* .. == . just like at / */
 		else {
 			/* checking mountpoint crossing is very different when stepping up */
 			struct svc_export *exp2 = NULL;
-			struct dentry *dp;
+			struct dentry *dp, *old;
 			struct vfsmount *mnt = mntget(exp->ex_mnt);
 			dentry = dget(dparent);
 			while(follow_up(&mnt, &dentry))
 				;
-			dp = dget(dentry->d_parent);
-			dput(dentry);
-			dentry = dp;
+			old = dentry;
+			read_lock(&dparent_lock);
+			dp = dentry->d_parent;
 			for ( ; !exp2 && dp->d_parent != dp; dp=dp->d_parent)
 				exp2 = exp_get_by_name(exp->ex_client, mnt, dp);
 			if (!exp2) {
-				dput(dentry);
 				dentry = dget(dparent);
 			} else {
+				dget(dentry->d_parent);
 				exp = exp2;
 			}
+			read_unlock(&dparent_lock);
+			dput(old);
 			mntput(mnt);
 		}
 	} else {

fs/udf/dir.c

@@ -224,7 +224,7 @@ do_udf_readdir(struct inode * dir, struct file *filp, filldir_t filldir, void *d
 
 		if ( cfi.fileCharacteristics & FILE_PARENT )
 		{
-			iblock = udf_get_lb_pblock(dir->i_sb, UDF_I_LOCATION(filp->f_dentry->d_parent->d_inode), 0);
+			iblock = parent_ino(filp->f_dentry);
 			flen = 2;
 			memcpy(fname, "..", flen);
 			dt_type = DT_DIR;