1 files changed, 291 insertions, 0 deletions

diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
new file mode 100644
index 000000000000..f3e7a0bf068b
--- /dev/null
+++ b/fs/cachefiles/xattr.c
@@ -0,0 +1,291 @@
+/* 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 "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(dentry->d_inode);
+
+        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) {
+                kerror("Can't set xattr on %*.*s [%lu] (err %d)",
+                       dentry->d_name.len, dentry->d_name.len,
+                       dentry->d_name.name, dentry->d_inode->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;
+
+                kerror("Can't read xattr on %*.*s [%lu] (err %d)",
+                       dentry->d_name.len, dentry->d_name.len,
+                       dentry->d_name.name, dentry->d_inode->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:
+        kerror("Cache object %lu type xattr length incorrect",
+               dentry->d_inode->i_ino);
+        ret = -EIO;
+        goto error;
+
+bad_type:
+        xtype[2] = 0;
+        kerror("Cache object %*.*s [%lu] type %s not %s",
+               dentry->d_name.len, dentry->d_name.len,
+               dentry->d_name.name, dentry->d_inode->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(object->fscache.cookie);
+        ASSERT(dentry);
+
+        _enter("%p,#%d", object, auxdata->len);
+
+        /* attempt to install the cache metadata directly */
+        _debug("SET %s #%u", object->fscache.cookie->def->name, 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(object->fscache.cookie);
+        ASSERT(dentry);
+
+        _enter("%p,#%d", object, auxdata->len);
+
+        /* attempt to install the cache metadata directly */
+        _debug("SET %s #%u", object->fscache.cookie->def->name, 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 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(dentry->d_inode);
+
+        auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
+        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)",
+                                        dentry->d_inode->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)",
+                                                dentry->d_inode->i_ino, -ret);
+                        goto error;
+                }
+        }
+
+okay:
+        ret = 0;
+
+error:
+        kfree(auxbuf);
+        _leave(" = %d", ret);
+        return ret;
+
+bad_type_length:
+        kerror("Cache object %lu xattr length incorrect",
+               dentry->d_inode->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)",
+                                            dentry->d_inode->i_ino, -ret);
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}