linux/fs/xfs/xfs_attr_remote.h
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   1/*
   2 * Copyright (c) 2013 Red Hat, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#ifndef __XFS_ATTR_REMOTE_H__
  19#define __XFS_ATTR_REMOTE_H__
  20
  21#define XFS_ATTR3_RMT_MAGIC     0x5841524d      /* XARM */
  22
  23/*
  24 * There is one of these headers per filesystem block in a remote attribute.
  25 * This is done to ensure there is a 1:1 mapping between the attribute value
  26 * length and the number of blocks needed to store the attribute. This makes the
  27 * verification of a buffer a little more complex, but greatly simplifies the
  28 * allocation, reading and writing of these attributes as we don't have to guess
  29 * the number of blocks needed to store the attribute data.
  30 */
  31struct xfs_attr3_rmt_hdr {
  32        __be32  rm_magic;
  33        __be32  rm_offset;
  34        __be32  rm_bytes;
  35        __be32  rm_crc;
  36        uuid_t  rm_uuid;
  37        __be64  rm_owner;
  38        __be64  rm_blkno;
  39        __be64  rm_lsn;
  40};
  41
  42#define XFS_ATTR3_RMT_CRC_OFF   offsetof(struct xfs_attr3_rmt_hdr, rm_crc)
  43
  44#define XFS_ATTR3_RMT_BUF_SPACE(mp, bufsize)    \
  45        ((bufsize) - (xfs_sb_version_hascrc(&(mp)->m_sb) ? \
  46                        sizeof(struct xfs_attr3_rmt_hdr) : 0))
  47
  48extern const struct xfs_buf_ops xfs_attr3_rmt_buf_ops;
  49
  50int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
  51
  52int xfs_attr_rmtval_get(struct xfs_da_args *args);
  53int xfs_attr_rmtval_set(struct xfs_da_args *args);
  54int xfs_attr_rmtval_remove(struct xfs_da_args *args);
  55
  56#endif /* __XFS_ATTR_REMOTE_H__ */
  57
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