Initial import

1 files changed, 324 insertions, 0 deletions

diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
new file mode 100644
index 000000000..d31c1a72d
--- /dev/null
+++ b/fs/cachefiles/xattr.c
@@ -0,0 +1,324 @@
+/* CacheFiles extended attribute management
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/quotaops.h>
+#include <linux/xattr.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+static const char cachefiles_xattr_cache[] =
+	XATTR_USER_PREFIX "CacheFiles.cache";
+
+/*
+ * check the type label on an object
+ * - done using xattrs
+ */
+int cachefiles_check_object_type(struct cachefiles_object *object)
+{
+	struct dentry *dentry = object->dentry;
+	char type[3], xtype[3];
+	int ret;
+
+	ASSERT(dentry);
+	ASSERT(d_backing_inode(dentry));
+
+	if (!object->fscache.cookie)
+		strcpy(type, "C3");
+	else
+		snprintf(type, 3, "%02x", object->fscache.cookie->def->type);
+
+	_enter("%p{%s}", object, type);
+
+	/* attempt to install a type label directly */
+	ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2,
+			   XATTR_CREATE);
+	if (ret == 0) {
+		_debug("SET"); /* we succeeded */
+		goto error;
+	}
+
+	if (ret != -EEXIST) {
+		pr_err("Can't set xattr on %pd [%lu] (err %d)\n",
+		       dentry, d_backing_inode(dentry)->i_ino,
+		       -ret);
+		goto error;
+	}
+
+	/* read the current type label */
+	ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
+	if (ret < 0) {
+		if (ret == -ERANGE)
+			goto bad_type_length;
+
+		pr_err("Can't read xattr on %pd [%lu] (err %d)\n",
+		       dentry, d_backing_inode(dentry)->i_ino,
+		       -ret);
+		goto error;
+	}
+
+	/* check the type is what we're expecting */
+	if (ret != 2)
+		goto bad_type_length;
+
+	if (xtype[0] != type[0] || xtype[1] != type[1])
+		goto bad_type;
+
+	ret = 0;
+
+error:
+	_leave(" = %d", ret);
+	return ret;
+
+bad_type_length:
+	pr_err("Cache object %lu type xattr length incorrect\n",
+	       d_backing_inode(dentry)->i_ino);
+	ret = -EIO;
+	goto error;
+
+bad_type:
+	xtype[2] = 0;
+	pr_err("Cache object %pd [%lu] type %s not %s\n",
+	       dentry, d_backing_inode(dentry)->i_ino,
+	       xtype, type);
+	ret = -EIO;
+	goto error;
+}
+
+/*
+ * set the state xattr on a cache file
+ */
+int cachefiles_set_object_xattr(struct cachefiles_object *object,
+				struct cachefiles_xattr *auxdata)
+{
+	struct dentry *dentry = object->dentry;
+	int ret;
+
+	ASSERT(dentry);
+
+	_enter("%p,#%d", object, auxdata->len);
+
+	/* attempt to install the cache metadata directly */
+	_debug("SET #%u", auxdata->len);
+
+	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
+			   &auxdata->type, auxdata->len,
+			   XATTR_CREATE);
+	if (ret < 0 && ret != -ENOMEM)
+		cachefiles_io_error_obj(
+			object,
+			"Failed to set xattr with error %d", ret);
+
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * update the state xattr on a cache file
+ */
+int cachefiles_update_object_xattr(struct cachefiles_object *object,
+				   struct cachefiles_xattr *auxdata)
+{
+	struct dentry *dentry = object->dentry;
+	int ret;
+
+	ASSERT(dentry);
+
+	_enter("%p,#%d", object, auxdata->len);
+
+	/* attempt to install the cache metadata directly */
+	_debug("SET #%u", auxdata->len);
+
+	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
+			   &auxdata->type, auxdata->len,
+			   XATTR_REPLACE);
+	if (ret < 0 && ret != -ENOMEM)
+		cachefiles_io_error_obj(
+			object,
+			"Failed to update xattr with error %d", ret);
+
+	_leave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * check the consistency between the backing cache and the FS-Cache cookie
+ */
+int cachefiles_check_auxdata(struct cachefiles_object *object)
+{
+	struct cachefiles_xattr *auxbuf;
+	enum fscache_checkaux validity;
+	struct dentry *dentry = object->dentry;
+	ssize_t xlen;
+	int ret;
+
+	ASSERT(dentry);
+	ASSERT(d_backing_inode(dentry));
+	ASSERT(object->fscache.cookie->def->check_aux);
+
+	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
+	if (!auxbuf)
+		return -ENOMEM;
+
+	xlen = vfs_getxattr(dentry, cachefiles_xattr_cache,
+			    &auxbuf->type, 512 + 1);
+	ret = -ESTALE;
+	if (xlen < 1 ||
+	    auxbuf->type != object->fscache.cookie->def->type)
+		goto error;
+
+	xlen--;
+	validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen);
+	if (validity != FSCACHE_CHECKAUX_OKAY)
+		goto error;
+
+	ret = 0;
+error:
+	kfree(auxbuf);
+	return ret;
+}
+
+/*
+ * check the state xattr on a cache file
+ * - return -ESTALE if the object should be deleted
+ */
+int cachefiles_check_object_xattr(struct cachefiles_object *object,
+				  struct cachefiles_xattr *auxdata)
+{
+	struct cachefiles_xattr *auxbuf;
+	struct dentry *dentry = object->dentry;
+	int ret;
+
+	_enter("%p,#%d", object, auxdata->len);
+
+	ASSERT(dentry);
+	ASSERT(d_backing_inode(dentry));
+
+	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp);
+	if (!auxbuf) {
+		_leave(" = -ENOMEM");
+		return -ENOMEM;
+	}
+
+	/* read the current type label */
+	ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
+			   &auxbuf->type, 512 + 1);
+	if (ret < 0) {
+		if (ret == -ENODATA)
+			goto stale; /* no attribute - power went off
+				     * mid-cull? */
+
+		if (ret == -ERANGE)
+			goto bad_type_length;
+
+		cachefiles_io_error_obj(object,
+					"Can't read xattr on %lu (err %d)",
+					d_backing_inode(dentry)->i_ino, -ret);
+		goto error;
+	}
+
+	/* check the on-disk object */
+	if (ret < 1)
+		goto bad_type_length;
+
+	if (auxbuf->type != auxdata->type)
+		goto stale;
+
+	auxbuf->len = ret;
+
+	/* consult the netfs */
+	if (object->fscache.cookie->def->check_aux) {
+		enum fscache_checkaux result;
+		unsigned int dlen;
+
+		dlen = auxbuf->len - 1;
+
+		_debug("checkaux %s #%u",
+		       object->fscache.cookie->def->name, dlen);
+
+		result = fscache_check_aux(&object->fscache,
+					   &auxbuf->data, dlen);
+
+		switch (result) {
+			/* entry okay as is */
+		case FSCACHE_CHECKAUX_OKAY:
+			goto okay;
+
+			/* entry requires update */
+		case FSCACHE_CHECKAUX_NEEDS_UPDATE:
+			break;
+
+			/* entry requires deletion */
+		case FSCACHE_CHECKAUX_OBSOLETE:
+			goto stale;
+
+		default:
+			BUG();
+		}
+
+		/* update the current label */
+		ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
+				   &auxdata->type, auxdata->len,
+				   XATTR_REPLACE);
+		if (ret < 0) {
+			cachefiles_io_error_obj(object,
+						"Can't update xattr on %lu"
+						" (error %d)",
+						d_backing_inode(dentry)->i_ino, -ret);
+			goto error;
+		}
+	}
+
+okay:
+	ret = 0;
+
+error:
+	kfree(auxbuf);
+	_leave(" = %d", ret);
+	return ret;
+
+bad_type_length:
+	pr_err("Cache object %lu xattr length incorrect\n",
+	       d_backing_inode(dentry)->i_ino);
+	ret = -EIO;
+	goto error;
+
+stale:
+	ret = -ESTALE;
+	goto error;
+}
+
+/*
+ * remove the object's xattr to mark it stale
+ */
+int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
+				   struct dentry *dentry)
+{
+	int ret;
+
+	ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
+	if (ret < 0) {
+		if (ret == -ENOENT || ret == -ENODATA)
+			ret = 0;
+		else if (ret != -ENOMEM)
+			cachefiles_io_error(cache,
+					    "Can't remove xattr from %lu"
+					    " (error %d)",
+					    d_backing_inode(dentry)->i_ino, -ret);
+	}
+
+	_leave(" = %d", ret);
+	return ret;
+}