[Btrfs-devel] [PATCH 3/4] the main xattr support code
Josef Bacik
jbacik at redhat.com
Wed Nov 7 18:08:39 PST 2007
Hello,
This is the meat of everything. This handles the
adding/retreiving/listing/deleting of xattrs. There are comments scattered
throughout which I hope show what I'm trying to do. Thank you,
Josef
diff -r 9cb5f0f5c713 xattr.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/xattr.c Thu Nov 08 03:56:39 2007 -0500
@@ -0,0 +1,391 @@
+/*
+ * Copyright (C) 2007 Red Hat. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/rwsem.h>
+#include <linux/xattr.h>
+#include "ctree.h"
+#include "btrfs_inode.h"
+#include "transaction.h"
+#include "xattr.h"
+#include "disk-io.h"
+
+static struct xattr_handler *btrfs_xattr_handler_map[] = {
+ [BTRFS_XATTR_INDEX_USER] = &btrfs_xattr_user_handler,
+ [BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS] = &btrfs_xattr_acl_access_handler,
+ [BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT] = &btrfs_xattr_acl_default_handler,
+ [BTRFS_XATTR_INDEX_TRUSTED] = &btrfs_xattr_trusted_handler,
+ [BTRFS_XATTR_INDEX_SECURITY] = &btrfs_xattr_security_handler,
+ [BTRFS_XATTR_INDEX_SYSTEM] = &btrfs_xattr_system_handler,
+};
+
+struct xattr_handler *btrfs_xattr_handlers[] = {
+ &btrfs_xattr_user_handler,
+ &btrfs_xattr_acl_access_handler,
+ &btrfs_xattr_acl_default_handler,
+ &btrfs_xattr_trusted_handler,
+ &btrfs_xattr_security_handler,
+ &btrfs_xattr_system_handler,
+ NULL,
+};
+
+/*
+ * @param name - the xattr name
+ * @return - the xattr_handler for the xattr, NULL if its not found
+ *
+ * use this with listxattr where we don't already know the type of xattr we
+ * have
+ */
+static struct xattr_handler *find_btrfs_xattr_handler(const char *name)
+{
+ int name_len = strlen(name);
+ struct xattr_handler *handler = NULL;
+
+ for (handler = *btrfs_xattr_handlers; handler != NULL; handler++) {
+ int prefix_len = strlen(handler->prefix);
+
+ if (name_len < prefix_len)
+ continue;
+
+ if (memcmp(name, handler->prefix, prefix_len) == 0)
+ break;
+ }
+
+ return handler;
+}
+
+/*
+ * @param name_index - the index for the xattr handler
+ * @return the xattr_handler if we found it, NULL otherwise
+ *
+ * use this if we know the type of the xattr already
+ */
+static struct xattr_handler *btrfs_xattr_handler(int name_index)
+{
+ struct xattr_handler *handler = NULL;
+
+ if (name_index >= 0 &&
+ name_index < ARRAY_SIZE(btrfs_xattr_handler_map))
+ handler = btrfs_xattr_handler_map[name_index];
+
+ return handler;
+}
+
+static inline char *get_name(const char *name, int name_index)
+{
+ char *ret = NULL;
+ struct xattr_handler *handler = btrfs_xattr_handler(name_index);
+ int prefix_len;
+
+ if (!handler)
+ return ret;
+
+ prefix_len = strlen(handler->prefix);
+
+ ret = kmalloc(strlen(name) + prefix_len + 1, GFP_KERNEL);
+ if (!ret)
+ return ret;
+
+ memcpy(ret, handler->prefix, prefix_len);
+ memcpy(ret+prefix_len, name, strlen(name));
+ ret[prefix_len + strlen(name)] = '\0';
+
+ return ret;
+}
+
+ssize_t btrfs_xattr_get(struct inode *inode, int name_index,
+ const char *attr_name, void *buffer, size_t size)
+{
+ struct btrfs_dir_item *di;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_path *path;
+ struct xattr_handler *handler = btrfs_xattr_handler(name_index);
+ int ret = 0;
+ char *data_ptr, *name;
+
+ if (!handler)
+ return -EOPNOTSUPP;
+
+ name = get_name(attr_name, name_index);
+ if (!name)
+ return -ENOMEM;
+
+ mutex_lock(&root->fs_info->fs_mutex);
+ /* lookup the xattr by name */
+ path = btrfs_alloc_path();
+ BUG_ON(!path);
+ di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
+ strlen(name), 0);
+ if (!di || IS_ERR(di)) {
+ ret = -ENODATA;
+ goto out;
+ }
+
+ /* if size is 0, that means we want the size of the attr */
+ if (!size) {
+ ret = btrfs_dir_data_len(di);
+ goto out;
+ }
+
+ /* now get the data out of our dir_item */
+ if (btrfs_dir_data_len(di) > size) {
+ ret = -ERANGE;
+ goto out;
+ }
+ data_ptr = (char *)(di + 1) + btrfs_dir_name_len(di);
+ memcpy(buffer, data_ptr, btrfs_dir_data_len(di));
+ ret = btrfs_dir_data_len(di);
+
+out:
+ kfree(name);
+ btrfs_free_path(path);
+ mutex_unlock(&root->fs_info->fs_mutex);
+ return ret;
+}
+
+int btrfs_xattr_set(struct inode *inode, int name_index,
+ const char *attr_name, const void *value, size_t size,
+ int flags)
+{
+ struct btrfs_dir_item *di;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_path *path;
+ struct xattr_handler *handler = btrfs_xattr_handler(name_index);
+ char *name;
+ int ret = 0;
+
+ if (!handler)
+ return -EOPNOTSUPP;
+
+ name = get_name(attr_name, name_index);
+ if (!name)
+ return -ENOMEM;
+
+ mutex_lock(&root->fs_info->fs_mutex);
+ trans = btrfs_start_transaction(root, 1);
+ btrfs_set_trans_block_group(trans, inode);
+
+ /* first lets see if we already have this xattr */
+ path = btrfs_alloc_path();
+ BUG_ON(!path);
+ di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
+ strlen(name), 1);
+ if (IS_ERR(di)) {
+ ret = PTR_ERR(di);
+ goto out;
+ }
+
+ /* ok we already have this xattr, lets remove it */
+ if (di) {
+ /* if we want create only exit */
+ if (flags & XATTR_CREATE) {
+ ret = -EEXIST;
+ goto out;
+ }
+
+ ret = btrfs_delete_one_dir_name(trans, root, path, di);
+ if (ret)
+ goto out;
+ btrfs_release_path(root, path);
+
+ /* if we don't have a value then we are removing the xattr */
+ if (!value)
+ goto out;
+ } else if (flags & XATTR_REPLACE) {
+ /* we couldn't find the attr to replace, so error out */
+ ret = -ENODATA;
+ goto out;
+ }
+
+ /* ok we have to create a completely new xattr */
+ ret = btrfs_insert_xattr_item(trans, root, name, strlen(name),
+ value, size, inode->i_ino);
+ if (ret)
+ goto out;
+
+out:
+ kfree(name);
+ btrfs_free_path(path);
+ btrfs_end_transaction(trans, root);
+ mutex_unlock(&root->fs_info->fs_mutex);
+ return ret;
+}
+
+ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+ struct btrfs_key key;
+ struct inode *inode = dentry->d_inode;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_path *path;
+ struct btrfs_item *item;
+ struct btrfs_leaf *leaf;
+ struct btrfs_dir_item *di;
+ struct xattr_handler *handler;
+ int ret = 0, slot, advance;
+ size_t total_size = 0, size_left = size, written;
+ char *name_ptr;
+ u32 nritems;
+
+ /*
+ * ok we want all objects associated with this id.
+ * NOTE: we set key.offset = 0; because we want to start with the
+ * first xattr that we find and walk forward
+ */
+ key.objectid = inode->i_ino;
+ key.flags = 0;
+ btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
+ key.offset = 0;
+
+ path = btrfs_alloc_path();
+ path->reada = 2;
+ BUG_ON(!path);
+
+ mutex_lock(&root->fs_info->fs_mutex);
+
+ /* search for our xattrs */
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0)
+ goto err;
+ ret = 0;
+ advance = 0;
+ while (1) {
+ leaf = btrfs_buffer_leaf(path->nodes[0]);
+ nritems = btrfs_header_nritems(&leaf->header);
+ slot = path->slots[0];
+
+ /* this is where we start walking through the path */
+ if (advance || slot >= nritems) {
+ /*
+ * if we've reached the last slot in this leaf we need
+ * to go to the next leaf and reset everything
+ */
+ if (slot >= nritems-1) {
+ ret = btrfs_next_leaf(root, path);
+ if (ret)
+ break;
+ leaf = btrfs_buffer_leaf(path->nodes[0]);
+ nritems = btrfs_header_nritems(&leaf->header);
+ slot = path->slots[0];
+ } else {
+ /*
+ * just walking through the slots on this leaf
+ */
+ slot++;
+ path->slots[0]++;
+ }
+ }
+ advance = 1;
+
+ item = leaf->items + slot;
+
+ /* check to make sure this item is what we want */
+ if (btrfs_disk_key_objectid(&item->key) != key.objectid)
+ break;
+ if (btrfs_disk_key_type(&item->key) != BTRFS_XATTR_ITEM_KEY)
+ break;
+
+ di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+
+ total_size += btrfs_dir_name_len(di)+1;
+
+ /* we are just looking for how big our buffer needs to be */
+ if (!size)
+ continue;
+
+ /* find our handler for this xattr */
+ name_ptr = (char *)(di + 1);
+ handler = find_btrfs_xattr_handler(name_ptr);
+ if (!handler) {
+ printk(KERN_ERR "btrfs: unsupported xattr found\n");
+ continue;
+ }
+
+ /* call the list function associated with this xattr */
+ written = handler->list(inode, buffer, size_left, name_ptr,
+ btrfs_dir_name_len(di));
+ if (written < 0) {
+ ret = -ERANGE;
+ break;
+ }
+
+ size_left -= written;
+ buffer += written;
+ }
+ ret = total_size;
+
+err:
+ btrfs_release_path(root, path);
+ btrfs_free_path(path);
+ mutex_unlock(&root->fs_info->fs_mutex);
+
+ return ret;
+}
+
+/*
+ * delete all the xattrs associated with the inode. fs_mutex should be
+ * held when we come into here
+ */
+int btrfs_delete_xattrs(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct inode *inode)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct btrfs_item *item;
+ struct btrfs_leaf *leaf;
+ int ret;
+
+ path = btrfs_alloc_path();
+ BUG_ON(!path);
+ key.objectid = inode->i_ino;
+ key.flags = 0;
+ btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
+ key.offset = (u64)-1;
+
+ while(1) {
+ /* look for our next xattr */
+ ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+ if (ret < 0)
+ goto out;
+ BUG_ON(ret == 0);
+
+ if (path->slots[0] == 0)
+ break;
+
+ path->slots[0]--;
+ leaf = btrfs_buffer_leaf(path->nodes[0]);
+ item = leaf->items + path->slots[0];
+
+ if (btrfs_disk_key_objectid(&item->key) != key.objectid)
+ break;
+ if (btrfs_disk_key_type(&item->key) != BTRFS_XATTR_ITEM_KEY)
+ break;
+
+ ret = btrfs_del_item(trans, root, path);
+ BUG_ON(ret);
+ btrfs_release_path(root, path);
+ }
+ ret = 0;
+out:
+ btrfs_release_path(root, path);
+ btrfs_free_path(path);
+
+ return ret;
+}
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