Re: [PATCH]: nfsd: more vfs_getxattr

[Christoph Hellwig <hch@lst.de>]

On Sun, Nov 06, 2005 at 10:21:43PM -0800, Andrew Morton wrote:
> Christoph Hellwig <hch@lst.de> wrote:
> >
> > looks like I missed NFSv4 previously.
> 
> When sending fixes for earlier patches, it greatly helps if you can
> identify which patch it is that needs fixing.  Usually it's obvious, but in
> this case it's not.

vfs_getxattr was introduced in

 [PATCH 1/8] add vfs_* helpers for xattr operations

but at that point it was just a cleanup.  it only became mandatory in
later patches to remove xattr checks in the filesystems.

> 
> > +	*buf = kmalloc(buflen, GFP_KERNEL);
> > +	if (!buf)
> > +		return -ENOMEM;
> 
> That's obviously broken.

Fixed one below:


Index: linux-2.6/fs/nfsd/vfs.c
===================================================================
--- linux-2.6.orig/fs/nfsd/vfs.c	2005-11-06 22:25:55.000000000 +0100
+++ linux-2.6/fs/nfsd/vfs.c	2005-11-07 04:22:05.000000000 +0100
@@ -358,8 +358,30 @@
 	goto out;
 }
 
-#if defined(CONFIG_NFSD_V4)
+#if defined(CONFIG_NFSD_V2_ACL) || \
+    defined(CONFIG_NFSD_V3_ACL) || \
+    defined(CONFIG_NFSD_V4)
+static ssize_t nfsd_getxattr(struct dentry *dentry, char *key, void **buf)
+{
+	ssize_t buflen;
+	int error;
+
+	buflen = vfs_getxattr(dentry, key, NULL, 0);
+	if (buflen <= 0)
+		return buflen;
+
+	*buf = kmalloc(buflen, GFP_KERNEL);
+	if (!*buf)
+		return -ENOMEM;
+
+	error = vfs_getxattr(dentry, key, *buf, buflen);
+	if (error < 0)
+		return error;
+	return buflen;
+}
+#endif
 
+#if defined(CONFIG_NFSD_V4)
 static int
 set_nfsv4_acl_one(struct dentry *dentry, struct posix_acl *pacl, char *key)
 {
@@ -439,30 +461,17 @@
 static struct posix_acl *
 _get_posix_acl(struct dentry *dentry, char *key)
 {
-	char *buf = NULL;
-	int buflen, error = 0;
+	void *buf = NULL;
 	struct posix_acl *pacl = NULL;
+	int buflen;
 
-	buflen = vfs_getxattr(dentry, key, NULL, 0);
-	if (buflen <= 0) {
-		pacl = ERR_PTR(buflen < 0 ? buflen : -ENODATA);
-		goto out;
-	}
-
-	buf = kmalloc(buflen, GFP_KERNEL);
-	if (buf == NULL) {
-		pacl = ERR_PTR(-ENOMEM);
-		goto out;
-	}
-
-	error = vfs_getxattr(dentry, key, buf, buflen);
-	if (error < 0) {
-		pacl = ERR_PTR(error);
-		goto out;
-	}
+	buflen = nfsd_getxattr(dentry, key, &buf);
+	if (!buflen)
+		buflen = -ENODATA;
+	if (buflen <= 0)
+		return ERR_PTR(buflen);
 
 	pacl = posix_acl_from_xattr(buf, buflen);
- out:
 	kfree(buf);
 	return pacl;
 }
@@ -1846,39 +1855,25 @@
 	ssize_t size;
 	struct posix_acl *acl;
 
-	if (!IS_POSIXACL(inode) || !inode->i_op || !inode->i_op->getxattr)
+	if (!IS_POSIXACL(inode))
+		return ERR_PTR(-EOPNOTSUPP);
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		name = POSIX_ACL_XATTR_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		name = POSIX_ACL_XATTR_DEFAULT;
+		break;
+	default:
 		return ERR_PTR(-EOPNOTSUPP);
-	switch(type) {
-		case ACL_TYPE_ACCESS:
-			name = POSIX_ACL_XATTR_ACCESS;
-			break;
-		case ACL_TYPE_DEFAULT:
-			name = POSIX_ACL_XATTR_DEFAULT;
-			break;
-		default:
-			return ERR_PTR(-EOPNOTSUPP);
 	}
 
-	size = inode->i_op->getxattr(fhp->fh_dentry, name, NULL, 0);
+	size = nfsd_getxattr(fhp->fh_dentry, name, &value);
+	if (size < 0)
+		return ERR_PTR(size);
 
-	if (size < 0) {
-		acl = ERR_PTR(size);
-		goto getout;
-	} else if (size > 0) {
-		value = kmalloc(size, GFP_KERNEL);
-		if (!value) {
-			acl = ERR_PTR(-ENOMEM);
-			goto getout;
-		}
-		size = inode->i_op->getxattr(fhp->fh_dentry, name, value, size);
-		if (size < 0) {
-			acl = ERR_PTR(size);
-			goto getout;
-		}
-	}
 	acl = posix_acl_from_xattr(value, size);
-
-getout:
 	kfree(value);
 	return acl;
 }