path: root/fs/xfs/xfs_attr_item.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2022 Oracle.  All Rights Reserved.
 * Author: Allison Henderson <allison.henderson@oracle.com>
 */

#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_shared.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_bmap_btree.h"
#include "xfs_trans_priv.h"
#include "xfs_log.h"
#include "xfs_inode.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_attr_item.h"
#include "xfs_trace.h"
#include "xfs_trans_space.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_log_priv.h"
#include "xfs_log_recover.h"
#include "xfs_parent.h"

struct kmem_cache		*xfs_attri_cache;
struct kmem_cache		*xfs_attrd_cache;

static const struct xfs_item_ops xfs_attri_item_ops;
static const struct xfs_item_ops xfs_attrd_item_ops;

static inline struct xfs_attri_log_item *ATTRI_ITEM(struct xfs_log_item *lip)
{
	return container_of(lip, struct xfs_attri_log_item, attri_item);
}

/*
 * Shared xattr name/value buffers for logged extended attribute operations
 *
 * When logging updates to extended attributes, we can create quite a few
 * attribute log intent items for a single xattr update.  To avoid cycling the
 * memory allocator and memcpy overhead, the name (and value, for setxattr)
 * are kept in a refcounted object that is shared across all related log items
 * and the upper-level deferred work state structure.  The shared buffer has
 * a control structure, followed by the name, and then the value.
 */

static inline struct xfs_attri_log_nameval *
xfs_attri_log_nameval_get(
	struct xfs_attri_log_nameval	*nv)
{
	if (!refcount_inc_not_zero(&nv->refcount))
		return NULL;
	return nv;
}

static inline void
xfs_attri_log_nameval_put(
	struct xfs_attri_log_nameval	*nv)
{
	if (!nv)
		return;
	if (refcount_dec_and_test(&nv->refcount))
		kvfree(nv);
}

static inline struct xfs_attri_log_nameval *
xfs_attri_log_nameval_alloc(
	const void			*name,
	unsigned int			name_len,
	const void			*new_name,
	unsigned int			new_name_len,
	const void			*value,
	unsigned int			value_len,
	const void			*new_value,
	unsigned int			new_value_len)
{
	struct xfs_attri_log_nameval	*nv;

	/*
	 * This could be over 64kB in length, so we have to use kvmalloc() for
	 * this. But kvmalloc() utterly sucks, so we use our own version.
	 */
	nv = xlog_kvmalloc(sizeof(struct xfs_attri_log_nameval) +
					name_len + new_name_len + value_len +
					new_value_len);

	nv->name.i_addr = nv + 1;
	nv->name.i_len = name_len;
	nv->name.i_type = XLOG_REG_TYPE_ATTR_NAME;
	memcpy(nv->name.i_addr, name, name_len);

	if (new_name_len) {
		nv->new_name.i_addr = nv->name.i_addr + name_len;
		nv->new_name.i_len = new_name_len;
		memcpy(nv->new_name.i_addr, new_name, new_name_len);
	} else {
		nv->new_name.i_addr = NULL;
		nv->new_name.i_len = 0;
	}
	nv->new_name.i_type = XLOG_REG_TYPE_ATTR_NEWNAME;

	if (value_len) {
		nv->value.i_addr = nv->name.i_addr + name_len + new_name_len;
		nv->value.i_len = value_len;
		memcpy(nv->value.i_addr, value, value_len);
	} else {
		nv->value.i_addr = NULL;
		nv->value.i_len = 0;
	}
	nv