usr/src/uts/common/fs/zfs/sys/zfs_rlock.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #ifndef _SYS_FS_ZFS_RLOCK_H
  27 #define _SYS_FS_ZFS_RLOCK_H
  28
  29 #ifdef  __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 #ifdef _KERNEL
  34
  35 #include <sys/zfs_znode.h>
  36
  37 typedef enum {
  38         RL_READER,
  39         RL_WRITER,
  40         RL_APPEND
  41 } rl_type_t;
  42
  43 typedef struct rl {
  44         znode_t *r_zp;          /* znode this lock applies to */
  45         avl_node_t r_node;      /* avl node link */
  46         uint64_t r_off;         /* file range offset */
  47         uint64_t r_len;         /* file range length */
  48         uint_t r_cnt;           /* range reference count in tree */
  49         rl_type_t r_type;       /* range type */
  50         kcondvar_t r_wr_cv;     /* cv for waiting writers */
  51         kcondvar_t r_rd_cv;     /* cv for waiting readers */
  52         uint8_t r_proxy;        /* acting for original range */
  53         uint8_t r_write_wanted; /* writer wants to lock this range */
  54         uint8_t r_read_wanted;  /* reader wants to lock this range */
  55 } rl_t;
  56
  57 /*
  58  * Lock a range (offset, length) as either shared (RL_READER)
  59  * or exclusive (RL_WRITER or RL_APPEND).  RL_APPEND is a special type that
  60  * is converted to RL_WRITER that specified to lock from the start of the
  61  * end of file.  Returns the range lock structure.
  62  */
  63 rl_t *zfs_range_lock(znode_t *zp, uint64_t off, uint64_t len, rl_type_t type);
  64
  65 /* Unlock range and destroy range lock structure. */
  66 void zfs_range_unlock(rl_t *rl);
  67
  68 /*
  69  * Reduce range locked as RW_WRITER from whole file to specified range.
  70  * Asserts the whole file was previously locked.
  71  */
  72 void zfs_range_reduce(rl_t *rl, uint64_t off, uint64_t len);
  73
  74 /*
  75  * AVL comparison function used to order range locks
  76  * Locks are ordered on the start offset of the range.
  77  */
  78 int zfs_range_compare(const void *arg1, const void *arg2);
  79
  80 #endif /* _KERNEL */
  81
  82 #ifdef  __cplusplus
  83 }
  84 #endif
  85
  86 #endif  /* _SYS_FS_ZFS_RLOCK_H */