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 000000000000..f4ac5e0bbad1
--- /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,
+};