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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  30 
  31 #ifdef  __cplusplus
  32 extern "C" {
  33 #endif
  34 
  35 #ifdef _KERNEL
  36 
  37 #include <sys/zfs_znode.h>
  38 
  39 typedef enum {
  40         RL_READER,
  41         RL_WRITER,
  42         RL_APPEND
  43 } rl_type_t;
  44 
  45 typedef struct rl {
  46         znode_t *r_zp;          /* znode this lock applies to */
  47         avl_node_t r_node;      /* avl node link */
  48         uint64_t r_off;         /* file range offset */
  49         uint64_t r_len;         /* file range length */
  50         uint_t r_cnt;           /* range reference count in tree */
  51         rl_type_t r_type;       /* range type */
  52         kcondvar_t r_wr_cv;     /* cv for waiting writers */
  53         kcondvar_t r_rd_cv;     /* cv for waiting readers */
  54         uint8_t r_proxy;        /* acting for original range */
  55         uint8_t r_write_wanted; /* writer wants to lock this range */
  56         uint8_t r_read_wanted;  /* reader wants to lock this range */
  57 } rl_t;
  58 
  59 /*
  60  * Lock a range (offset, length) as either shared (READER)
  61  * or exclusive (WRITER or APPEND). APPEND is a special type that
  62  * is converted to WRITER that specified to lock from the start of the
  63  * end of file.  zfs_range_lock() returns the range lock structure.
  64  */
  65 rl_t *zfs_range_lock(znode_t *zp, uint64_t off, uint64_t len, rl_type_t type);
  66 
  67 /*
  68  * Unlock range and destroy range lock structure.
  69  */
  70 void zfs_range_unlock(rl_t *rl);
  71 
  72 /*
  73  * Reduce range locked as RW_WRITER from whole file to specified range.
  74  * Asserts the whole file was previously locked.
  75  */
  76 void zfs_range_reduce(rl_t *rl, uint64_t off, uint64_t len);
  77 
  78 /*
  79  * AVL comparison function used to compare range locks
  80  */
  81 int zfs_range_compare(const void *arg1, const void *arg2);
  82 
  83 #endif /* _KERNEL */
  84 
  85 #ifdef  __cplusplus
  86 }
  87 #endif
  88 
  89 #endif  /* _SYS_FS_ZFS_RLOCK_H */