fs/xfs/xfs_attr_remote.h

   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  */
  31 struct 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
  48 extern const struct xfs_buf_ops xfs_attr3_rmt_buf_ops;
  49
  50 int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
  51
  52 int xfs_attr_rmtval_get(struct xfs_da_args *args);
  53 int xfs_attr_rmtval_set(struct xfs_da_args *args);
  54 int xfs_attr_rmtval_remove(struct xfs_da_args *args);
  55
  56 #endif /* __XFS_ATTR_REMOTE_H__ */