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504 lines
13 KiB
504 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2007 Red Hat. All rights reserved. |
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*/ |
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|
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#include <linux/init.h> |
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#include <linux/fs.h> |
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#include <linux/slab.h> |
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#include <linux/rwsem.h> |
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#include <linux/xattr.h> |
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#include <linux/security.h> |
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#include <linux/posix_acl_xattr.h> |
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#include <linux/iversion.h> |
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#include <linux/sched/mm.h> |
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#include "ctree.h" |
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#include "btrfs_inode.h" |
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#include "transaction.h" |
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#include "xattr.h" |
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#include "disk-io.h" |
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#include "props.h" |
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#include "locking.h" |
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int btrfs_getxattr(struct inode *inode, const char *name, |
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void *buffer, size_t size) |
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{ |
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struct btrfs_dir_item *di; |
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struct btrfs_root *root = BTRFS_I(inode)->root; |
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struct btrfs_path *path; |
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struct extent_buffer *leaf; |
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int ret = 0; |
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unsigned long data_ptr; |
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path = btrfs_alloc_path(); |
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if (!path) |
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return -ENOMEM; |
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|
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/* lookup the xattr by name */ |
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di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)), |
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name, strlen(name), 0); |
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if (!di) { |
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ret = -ENODATA; |
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goto out; |
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} else if (IS_ERR(di)) { |
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ret = PTR_ERR(di); |
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goto out; |
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} |
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|
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leaf = path->nodes[0]; |
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/* if size is 0, that means we want the size of the attr */ |
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if (!size) { |
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ret = btrfs_dir_data_len(leaf, di); |
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goto out; |
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} |
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|
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/* now get the data out of our dir_item */ |
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if (btrfs_dir_data_len(leaf, di) > size) { |
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ret = -ERANGE; |
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goto out; |
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} |
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/* |
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* The way things are packed into the leaf is like this |
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* |struct btrfs_dir_item|name|data| |
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* where name is the xattr name, so security.foo, and data is the |
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* content of the xattr. data_ptr points to the location in memory |
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* where the data starts in the in memory leaf |
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*/ |
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data_ptr = (unsigned long)((char *)(di + 1) + |
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btrfs_dir_name_len(leaf, di)); |
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read_extent_buffer(leaf, buffer, data_ptr, |
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btrfs_dir_data_len(leaf, di)); |
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ret = btrfs_dir_data_len(leaf, di); |
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out: |
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btrfs_free_path(path); |
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return ret; |
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} |
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int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode, |
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const char *name, const void *value, size_t size, int flags) |
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{ |
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struct btrfs_dir_item *di = NULL; |
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struct btrfs_root *root = BTRFS_I(inode)->root; |
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struct btrfs_fs_info *fs_info = root->fs_info; |
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struct btrfs_path *path; |
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size_t name_len = strlen(name); |
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int ret = 0; |
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ASSERT(trans); |
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if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info)) |
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return -ENOSPC; |
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path = btrfs_alloc_path(); |
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if (!path) |
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return -ENOMEM; |
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path->skip_release_on_error = 1; |
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if (!value) { |
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di = btrfs_lookup_xattr(trans, root, path, |
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btrfs_ino(BTRFS_I(inode)), name, name_len, -1); |
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if (!di && (flags & XATTR_REPLACE)) |
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ret = -ENODATA; |
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else if (IS_ERR(di)) |
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ret = PTR_ERR(di); |
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else if (di) |
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ret = btrfs_delete_one_dir_name(trans, root, path, di); |
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goto out; |
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} |
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/* |
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* For a replace we can't just do the insert blindly. |
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* Do a lookup first (read-only btrfs_search_slot), and return if xattr |
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* doesn't exist. If it exists, fall down below to the insert/replace |
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* path - we can't race with a concurrent xattr delete, because the VFS |
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* locks the inode's i_mutex before calling setxattr or removexattr. |
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*/ |
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if (flags & XATTR_REPLACE) { |
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ASSERT(inode_is_locked(inode)); |
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di = btrfs_lookup_xattr(NULL, root, path, |
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btrfs_ino(BTRFS_I(inode)), name, name_len, 0); |
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if (!di) |
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ret = -ENODATA; |
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else if (IS_ERR(di)) |
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ret = PTR_ERR(di); |
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if (ret) |
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goto out; |
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btrfs_release_path(path); |
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di = NULL; |
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} |
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ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)), |
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name, name_len, value, size); |
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if (ret == -EOVERFLOW) { |
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/* |
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* We have an existing item in a leaf, split_leaf couldn't |
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* expand it. That item might have or not a dir_item that |
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* matches our target xattr, so lets check. |
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*/ |
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ret = 0; |
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btrfs_assert_tree_locked(path->nodes[0]); |
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di = btrfs_match_dir_item_name(fs_info, path, name, name_len); |
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if (!di && !(flags & XATTR_REPLACE)) { |
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ret = -ENOSPC; |
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goto out; |
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} |
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} else if (ret == -EEXIST) { |
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ret = 0; |
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di = btrfs_match_dir_item_name(fs_info, path, name, name_len); |
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ASSERT(di); /* logic error */ |
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} else if (ret) { |
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goto out; |
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} |
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if (di && (flags & XATTR_CREATE)) { |
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ret = -EEXIST; |
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goto out; |
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} |
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if (di) { |
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/* |
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* We're doing a replace, and it must be atomic, that is, at |
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* any point in time we have either the old or the new xattr |
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* value in the tree. We don't want readers (getxattr and |
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* listxattrs) to miss a value, this is specially important |
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* for ACLs. |
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*/ |
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const int slot = path->slots[0]; |
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struct extent_buffer *leaf = path->nodes[0]; |
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const u16 old_data_len = btrfs_dir_data_len(leaf, di); |
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const u32 item_size = btrfs_item_size_nr(leaf, slot); |
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const u32 data_size = sizeof(*di) + name_len + size; |
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struct btrfs_item *item; |
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unsigned long data_ptr; |
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char *ptr; |
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if (size > old_data_len) { |
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if (btrfs_leaf_free_space(leaf) < |
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(size - old_data_len)) { |
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ret = -ENOSPC; |
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goto out; |
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} |
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} |
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if (old_data_len + name_len + sizeof(*di) == item_size) { |
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/* No other xattrs packed in the same leaf item. */ |
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if (size > old_data_len) |
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btrfs_extend_item(path, size - old_data_len); |
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else if (size < old_data_len) |
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btrfs_truncate_item(path, data_size, 1); |
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} else { |
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/* There are other xattrs packed in the same item. */ |
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ret = btrfs_delete_one_dir_name(trans, root, path, di); |
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if (ret) |
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goto out; |
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btrfs_extend_item(path, data_size); |
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} |
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item = btrfs_item_nr(slot); |
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ptr = btrfs_item_ptr(leaf, slot, char); |
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ptr += btrfs_item_size(leaf, item) - data_size; |
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di = (struct btrfs_dir_item *)ptr; |
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btrfs_set_dir_data_len(leaf, di, size); |
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data_ptr = ((unsigned long)(di + 1)) + name_len; |
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write_extent_buffer(leaf, value, data_ptr, size); |
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btrfs_mark_buffer_dirty(leaf); |
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} else { |
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/* |
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* Insert, and we had space for the xattr, so path->slots[0] is |
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* where our xattr dir_item is and btrfs_insert_xattr_item() |
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* filled it. |
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*/ |
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} |
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out: |
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btrfs_free_path(path); |
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if (!ret) { |
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set_bit(BTRFS_INODE_COPY_EVERYTHING, |
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&BTRFS_I(inode)->runtime_flags); |
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clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags); |
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} |
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return ret; |
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} |
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/* |
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* @value: "" makes the attribute to empty, NULL removes it |
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*/ |
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int btrfs_setxattr_trans(struct inode *inode, const char *name, |
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const void *value, size_t size, int flags) |
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{ |
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struct btrfs_root *root = BTRFS_I(inode)->root; |
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struct btrfs_trans_handle *trans; |
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const bool start_trans = (current->journal_info == NULL); |
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int ret; |
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if (start_trans) { |
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/* |
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* 1 unit for inserting/updating/deleting the xattr |
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* 1 unit for the inode item update |
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*/ |
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trans = btrfs_start_transaction(root, 2); |
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if (IS_ERR(trans)) |
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return PTR_ERR(trans); |
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} else { |
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/* |
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* This can happen when smack is enabled and a directory is being |
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* created. It happens through d_instantiate_new(), which calls |
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* smack_d_instantiate(), which in turn calls __vfs_setxattr() to |
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* set the transmute xattr (XATTR_NAME_SMACKTRANSMUTE) on the |
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* inode. We have already reserved space for the xattr and inode |
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* update at btrfs_mkdir(), so just use the transaction handle. |
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* We don't join or start a transaction, as that will reset the |
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* block_rsv of the handle and trigger a warning for the start |
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* case. |
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*/ |
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ASSERT(strncmp(name, XATTR_SECURITY_PREFIX, |
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XATTR_SECURITY_PREFIX_LEN) == 0); |
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trans = current->journal_info; |
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} |
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ret = btrfs_setxattr(trans, inode, name, value, size, flags); |
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if (ret) |
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goto out; |
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inode_inc_iversion(inode); |
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inode->i_ctime = current_time(inode); |
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ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); |
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BUG_ON(ret); |
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out: |
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if (start_trans) |
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btrfs_end_transaction(trans); |
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return ret; |
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} |
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ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) |
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{ |
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struct btrfs_key key; |
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struct inode *inode = d_inode(dentry); |
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struct btrfs_root *root = BTRFS_I(inode)->root; |
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struct btrfs_path *path; |
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int ret = 0; |
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size_t total_size = 0, size_left = size; |
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/* |
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* ok we want all objects associated with this id. |
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* NOTE: we set key.offset = 0; because we want to start with the |
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* first xattr that we find and walk forward |
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*/ |
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key.objectid = btrfs_ino(BTRFS_I(inode)); |
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key.type = BTRFS_XATTR_ITEM_KEY; |
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key.offset = 0; |
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path = btrfs_alloc_path(); |
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if (!path) |
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return -ENOMEM; |
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path->reada = READA_FORWARD; |
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/* search for our xattrs */ |
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); |
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if (ret < 0) |
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goto err; |
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while (1) { |
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struct extent_buffer *leaf; |
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int slot; |
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struct btrfs_dir_item *di; |
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struct btrfs_key found_key; |
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u32 item_size; |
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u32 cur; |
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leaf = path->nodes[0]; |
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slot = path->slots[0]; |
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/* this is where we start walking through the path */ |
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if (slot >= btrfs_header_nritems(leaf)) { |
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/* |
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* if we've reached the last slot in this leaf we need |
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* to go to the next leaf and reset everything |
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*/ |
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ret = btrfs_next_leaf(root, path); |
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if (ret < 0) |
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goto err; |
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else if (ret > 0) |
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break; |
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continue; |
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} |
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btrfs_item_key_to_cpu(leaf, &found_key, slot); |
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/* check to make sure this item is what we want */ |
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if (found_key.objectid != key.objectid) |
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break; |
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if (found_key.type > BTRFS_XATTR_ITEM_KEY) |
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break; |
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if (found_key.type < BTRFS_XATTR_ITEM_KEY) |
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goto next_item; |
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di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); |
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item_size = btrfs_item_size_nr(leaf, slot); |
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cur = 0; |
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while (cur < item_size) { |
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u16 name_len = btrfs_dir_name_len(leaf, di); |
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u16 data_len = btrfs_dir_data_len(leaf, di); |
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u32 this_len = sizeof(*di) + name_len + data_len; |
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unsigned long name_ptr = (unsigned long)(di + 1); |
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total_size += name_len + 1; |
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/* |
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* We are just looking for how big our buffer needs to |
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* be. |
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*/ |
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if (!size) |
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goto next; |
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if (!buffer || (name_len + 1) > size_left) { |
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ret = -ERANGE; |
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goto err; |
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} |
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read_extent_buffer(leaf, buffer, name_ptr, name_len); |
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buffer[name_len] = '\0'; |
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size_left -= name_len + 1; |
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buffer += name_len + 1; |
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next: |
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cur += this_len; |
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di = (struct btrfs_dir_item *)((char *)di + this_len); |
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} |
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next_item: |
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path->slots[0]++; |
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} |
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ret = total_size; |
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err: |
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btrfs_free_path(path); |
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return ret; |
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} |
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static int btrfs_xattr_handler_get(const struct xattr_handler *handler, |
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struct dentry *unused, struct inode *inode, |
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const char *name, void *buffer, size_t size) |
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{ |
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name = xattr_full_name(handler, name); |
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return btrfs_getxattr(inode, name, buffer, size); |
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} |
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static int btrfs_xattr_handler_set(const struct xattr_handler *handler, |
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struct user_namespace *mnt_userns, |
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struct dentry *unused, struct inode *inode, |
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const char *name, const void *buffer, |
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size_t size, int flags) |
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{ |
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name = xattr_full_name(handler, name); |
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return btrfs_setxattr_trans(inode, name, buffer, size, flags); |
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} |
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static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, |
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struct user_namespace *mnt_userns, |
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struct dentry *unused, struct inode *inode, |
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const char *name, const void *value, |
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size_t size, int flags) |
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{ |
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int ret; |
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struct btrfs_trans_handle *trans; |
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struct btrfs_root *root = BTRFS_I(inode)->root; |
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name = xattr_full_name(handler, name); |
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ret = btrfs_validate_prop(name, value, size); |
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if (ret) |
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return ret; |
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trans = btrfs_start_transaction(root, 2); |
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if (IS_ERR(trans)) |
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return PTR_ERR(trans); |
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ret = btrfs_set_prop(trans, inode, name, value, size, flags); |
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if (!ret) { |
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inode_inc_iversion(inode); |
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inode->i_ctime = current_time(inode); |
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ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); |
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BUG_ON(ret); |
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} |
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btrfs_end_transaction(trans); |
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return ret; |
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} |
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static const struct xattr_handler btrfs_security_xattr_handler = { |
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.prefix = XATTR_SECURITY_PREFIX, |
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.get = btrfs_xattr_handler_get, |
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.set = btrfs_xattr_handler_set, |
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}; |
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static const struct xattr_handler btrfs_trusted_xattr_handler = { |
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.prefix = XATTR_TRUSTED_PREFIX, |
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.get = btrfs_xattr_handler_get, |
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.set = btrfs_xattr_handler_set, |
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}; |
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static const struct xattr_handler btrfs_user_xattr_handler = { |
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.prefix = XATTR_USER_PREFIX, |
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.get = btrfs_xattr_handler_get, |
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.set = btrfs_xattr_handler_set, |
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}; |
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static const struct xattr_handler btrfs_btrfs_xattr_handler = { |
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.prefix = XATTR_BTRFS_PREFIX, |
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.get = btrfs_xattr_handler_get, |
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.set = btrfs_xattr_handler_set_prop, |
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}; |
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const struct xattr_handler *btrfs_xattr_handlers[] = { |
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&btrfs_security_xattr_handler, |
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#ifdef CONFIG_BTRFS_FS_POSIX_ACL |
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&posix_acl_access_xattr_handler, |
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&posix_acl_default_xattr_handler, |
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#endif |
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&btrfs_trusted_xattr_handler, |
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&btrfs_user_xattr_handler, |
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&btrfs_btrfs_xattr_handler, |
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NULL, |
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}; |
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static int btrfs_initxattrs(struct inode *inode, |
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const struct xattr *xattr_array, void *fs_private) |
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{ |
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struct btrfs_trans_handle *trans = fs_private; |
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const struct xattr *xattr; |
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unsigned int nofs_flag; |
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char *name; |
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int err = 0; |
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/* |
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* We're holding a transaction handle, so use a NOFS memory allocation |
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* context to avoid deadlock if reclaim happens. |
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*/ |
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nofs_flag = memalloc_nofs_save(); |
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for (xattr = xattr_array; xattr->name != NULL; xattr++) { |
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name = kmalloc(XATTR_SECURITY_PREFIX_LEN + |
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strlen(xattr->name) + 1, GFP_KERNEL); |
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if (!name) { |
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err = -ENOMEM; |
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break; |
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} |
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strcpy(name, XATTR_SECURITY_PREFIX); |
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strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); |
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err = btrfs_setxattr(trans, inode, name, xattr->value, |
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xattr->value_len, 0); |
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kfree(name); |
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if (err < 0) |
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break; |
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} |
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memalloc_nofs_restore(nofs_flag); |
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return err; |
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} |
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int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, |
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struct inode *inode, struct inode *dir, |
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const struct qstr *qstr) |
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{ |
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return security_inode_init_security(inode, dir, qstr, |
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&btrfs_initxattrs, trans); |
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}
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