xattr support for btrfs

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 497 insertions, 0 deletions

diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
new file mode 100644
index 0000000..f4ac5e0
--- /dev/null
+++ b/fs/btrfs/xattr.c
@@ -0,0 +1,497 @@
+/*
+ * 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(struct extent_buffer *l,
+						      unsigned long name_ptr,
+						      u16 name_len)
+{
+	struct xattr_handler *handler = NULL;
+	int i = 0;
+
+	for (handler = btrfs_xattr_handlers[i]; handler != NULL; i++,
+	     handler = btrfs_xattr_handlers[i]) {
+		u16 prefix_len = strlen(handler->prefix);
+
+		if (name_len < prefix_len)
+			continue;
+
+		if (memcmp_extent_buffer(l, handler->prefix, name_ptr,
+					 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;
+}
+
+size_t btrfs_xattr_generic_list(struct inode *inode, char *list,
+				size_t list_size, const char *name,
+				size_t name_len)
+{
+	if (list && (name_len+1) <= list_size) {
+		memcpy(list, name, name_len);
+		list[name_len] = '\0';
+	} else
+		return -ERANGE;
+
+	return name_len+1;
+}
+
+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 extent_buffer *leaf;
+	struct xattr_handler *handler = btrfs_xattr_handler(name_index);
+	int ret = 0;
+	unsigned long data_ptr;
+	char *name;
+
+	if (!handler)
+		return -EOPNOTSUPP;
+
+	/* just in case... */
+	if (*attr_name == '\0')
+		return -EINVAL;
+
+	name = get_name(attr_name, name_index);
+	if (!name)
+		return -ENOMEM;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		kfree(name);
+		return -ENOMEM;
+	}
+
+	mutex_lock(&root->fs_info->fs_mutex);
+	/* lookup the xattr by name */
+	di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
+				strlen(name), 0);
+	if (!di || IS_ERR(di)) {
+		ret = -ENODATA;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+	/* if size is 0, that means we want the size of the attr */
+	if (!size) {
+		ret = btrfs_dir_data_len(leaf, di);
+		goto out;
+	}
+
+	/* now get the data out of our dir_item */
+	if (btrfs_dir_data_len(leaf, di) > size) {
+		ret = -ERANGE;
+		goto out;
+	}
+	data_ptr = (unsigned long)((char *)(di + 1) +
+				   btrfs_dir_name_len(leaf, di));
+	read_extent_buffer(leaf, buffer, data_ptr,
+			   btrfs_dir_name_len(leaf, di));
+	ret = btrfs_dir_data_len(leaf, di);
+
+out:
+	mutex_unlock(&root->fs_info->fs_mutex);
+	kfree(name);
+	btrfs_free_path(path);
+	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, mod = 0;
+
+	if (!handler)
+		return -EOPNOTSUPP;
+
+	/* just in case... */
+	if (*attr_name == '\0')
+		return -EINVAL;
+
+	name = get_name(attr_name, name_index);
+	if (!name)
+		return -ENOMEM;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		kfree(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 */
+	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) {
+			mod = 1;
+			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;
+	mod = 1;
+
+out:
+	if (mod) {
+		inode->i_ctime = CURRENT_TIME;
+		ret = btrfs_update_inode(trans, root, inode);
+	}
+
+	btrfs_end_transaction(trans, root);
+	mutex_unlock(&root->fs_info->fs_mutex);
+	kfree(name);
+	btrfs_free_path(path);
+
+	return ret;
+}
+
+ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+	struct btrfs_key key, found_key;
+	struct inode *inode = dentry->d_inode;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_path *path;
+	struct btrfs_item *item;
+	struct extent_buffer *leaf;
+	struct btrfs_dir_item *di;
+	struct xattr_handler *handler;
+	int ret = 0, slot, advance;
+	size_t total_size = 0, size_left = size, written;
+	unsigned long name_ptr;
+	char *name;
+	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;
+	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
+	key.offset = 0;
+
+	path = btrfs_alloc_path();
+	path->reada = 2;
+	if (!path)
+		return -ENOMEM;
+
+	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 = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		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 = path->nodes[0];
+				nritems = btrfs_header_nritems(leaf);
+				slot = path->slots[0];
+			} else {
+				/*
+				 * just walking through the slots on this leaf
+				 */
+				slot++;
+				path->slots[0]++;
+			}
+		}
+		advance = 1;
+
+		item = btrfs_item_nr(leaf, slot);
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+		/* check to make sure this item is what we want */
+		if (found_key.objectid != key.objectid)
+			break;
+		if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
+			break;
+
+		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+
+		total_size += btrfs_dir_name_len(leaf, 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 = (unsigned long)(di + 1);
+		handler = find_btrfs_xattr_handler(leaf, name_ptr,
+						   btrfs_dir_name_len(leaf, di));
+		if (!handler) {
+			printk(KERN_ERR "btrfs: unsupported xattr found\n");
+			continue;
+		}
+
+		name = kmalloc(btrfs_dir_name_len(leaf, di), GFP_KERNEL);
+		read_extent_buffer(leaf, name, name_ptr,
+				   btrfs_dir_name_len(leaf, di));
+
+		/* call the list function associated with this xattr */
+		written = handler->list(inode, buffer, size_left, name,
+					btrfs_dir_name_len(leaf, di));
+		kfree(name);
+
+		if (written < 0) {
+			ret = -ERANGE;
+			break;
+		}
+
+		size_left -= written;
+		buffer += written;
+	}
+	ret = total_size;
+
+err:
+	mutex_unlock(&root->fs_info->fs_mutex);
+	btrfs_free_path(path);
+
+	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, found_key;
+	struct btrfs_item *item;
+	struct extent_buffer *leaf;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = inode->i_ino;
+	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 = path->nodes[0];
+		item = btrfs_item_nr(leaf, path->slots[0]);
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+		if (found_key.objectid != key.objectid)
+			break;
+		if (btrfs_key_type(&found_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_free_path(path);
+
+	return ret;
+}
+
+/*
+ * Handler functions
+ */
+#define BTRFS_XATTR_SETGET_FUNCS(name, index)				\
+static int btrfs_xattr_##name##_get(struct inode *inode,		\
+				    const char *name, void *value,	\
+				    size_t size)			\
+{									\
+	return btrfs_xattr_get(inode, index, name, value, size);	\
+}									\
+static int btrfs_xattr_##name##_set(struct inode *inode,		\
+				    const char *name, const void *value,\
+				    size_t size, int flags)		\
+{									\
+	return btrfs_xattr_set(inode, index, name, value, size, flags);	\
+}									\
+
+BTRFS_XATTR_SETGET_FUNCS(security, BTRFS_XATTR_INDEX_SECURITY);
+BTRFS_XATTR_SETGET_FUNCS(system, BTRFS_XATTR_INDEX_SYSTEM);
+BTRFS_XATTR_SETGET_FUNCS(user, BTRFS_XATTR_INDEX_USER);
+BTRFS_XATTR_SETGET_FUNCS(trusted, BTRFS_XATTR_INDEX_TRUSTED);
+
+struct xattr_handler btrfs_xattr_security_handler = {
+	.prefix = XATTR_SECURITY_PREFIX,
+	.list	= btrfs_xattr_generic_list,
+	.get	= btrfs_xattr_security_get,
+	.set	= btrfs_xattr_security_set,
+};
+
+struct xattr_handler btrfs_xattr_system_handler = {
+	.prefix = XATTR_SYSTEM_PREFIX,
+	.list	= btrfs_xattr_generic_list,
+	.get	= btrfs_xattr_system_get,
+	.set	= btrfs_xattr_system_set,
+};
+
+struct xattr_handler btrfs_xattr_user_handler = {
+	.prefix	= XATTR_USER_PREFIX,
+	.list	= btrfs_xattr_generic_list,
+	.get	= btrfs_xattr_user_get,
+	.set	= btrfs_xattr_user_set,
+};
+
+struct xattr_handler btrfs_xattr_trusted_handler = {
+	.prefix = XATTR_USER_PREFIX,
+	.list	= btrfs_xattr_generic_list,
+	.get	= btrfs_xattr_trusted_get,
+	.set	= btrfs_xattr_trusted_set,
+};