drivers/md/dm-log.h

   1 /*
   2  * Copyright (C) 2003 Sistina Software
   3  *
   4  * This file is released under the LGPL.
   5  */
   6
   7 #ifndef DM_DIRTY_LOG
   8 #define DM_DIRTY_LOG
   9
  10 #include "dm.h"
  11
  12 typedef sector_t region_t;
  13
  14 struct dirty_log_type;
  15
  16 struct dirty_log {
  17         struct dirty_log_type *type;
  18         void *context;
  19 };
  20
  21 struct dirty_log_type {
  22         struct list_head list;
  23         const char *name;
  24         struct module *module;
  25         unsigned int use_count;
  26
  27         int (*ctr)(struct dirty_log *log, struct dm_target *ti,
  28                    unsigned int argc, char **argv);
  29         void (*dtr)(struct dirty_log *log);
  30
  31         /*
  32          * There are times when we don't want the log to touch
  33          * the disk.
  34          */
  35         int (*suspend)(struct dirty_log *log);
  36         int (*resume)(struct dirty_log *log);
  37
  38         /*
  39          * Retrieves the smallest size of region that the log can
  40          * deal with.
  41          */
  42         uint32_t (*get_region_size)(struct dirty_log *log);
  43
  44         /*
  45          * A predicate to say whether a region is clean or not.
  46          * May block.
  47          */
  48         int (*is_clean)(struct dirty_log *log, region_t region);
  49
  50         /*
  51          *  Returns: 0, 1, -EWOULDBLOCK, < 0
  52          *
  53          * A predicate function to check the area given by
  54          * [sector, sector + len) is in sync.
  55          *
  56          * If -EWOULDBLOCK is returned the state of the region is
  57          * unknown, typically this will result in a read being
  58          * passed to a daemon to deal with, since a daemon is
  59          * allowed to block.
  60          */
  61         int (*in_sync)(struct dirty_log *log, region_t region, int can_block);
  62
  63         /*
  64          * Flush the current log state (eg, to disk).  This
  65          * function may block.
  66          */
  67         int (*flush)(struct dirty_log *log);
  68
  69         /*
  70          * Mark an area as clean or dirty.  These functions may
  71          * block, though for performance reasons blocking should
  72          * be extremely rare (eg, allocating another chunk of
  73          * memory for some reason).
  74          */
  75         void (*mark_region)(struct dirty_log *log, region_t region);
  76         void (*clear_region)(struct dirty_log *log, region_t region);
  77
  78         /*
  79          * Returns: <0 (error), 0 (no region), 1 (region)
  80          *
  81          * The mirrord will need perform recovery on regions of
  82          * the mirror that are in the NOSYNC state.  This
  83          * function asks the log to tell the caller about the
  84          * next region that this machine should recover.
  85          *
  86          * Do not confuse this function with 'in_sync()', one
  87          * tells you if an area is synchronised, the other
  88          * assigns recovery work.
  89         */
  90         int (*get_resync_work)(struct dirty_log *log, region_t *region);
  91
  92         /*
  93          * This notifies the log that the resync status of a region
  94          * has changed.  It also clears the region from the recovering
  95          * list (if present).
  96          */
  97         void (*set_region_sync)(struct dirty_log *log,
  98                                 region_t region, int in_sync);
  99
 100         /*
 101          * Returns the number of regions that are in sync.
 102          */
 103         region_t (*get_sync_count)(struct dirty_log *log);
 104
 105         /*
 106          * Support function for mirror status requests.
 107          */
 108         int (*status)(struct dirty_log *log, status_type_t status_type,
 109                       char *result, unsigned int maxlen);
 110 };
 111
 112 int dm_register_dirty_log_type(struct dirty_log_type *type);
 113 int dm_unregister_dirty_log_type(struct dirty_log_type *type);
 114
 115
 116 /*
 117  * Make sure you use these two functions, rather than calling
 118  * type->constructor/destructor() directly.
 119  */
 120 struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
 121                                       unsigned int argc, char **argv);
 122 void dm_destroy_dirty_log(struct dirty_log *log);
 123
 124 /*
 125  * init/exit functions.
 126  */
 127 int dm_dirty_log_init(void);
 128 void dm_dirty_log_exit(void);
 129
 130 #endif