dm-kcopyd.h 2.9 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990
  1. /*
  2. * Copyright (C) 2001 - 2003 Sistina Software
  3. * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
  4. *
  5. * kcopyd provides a simple interface for copying an area of one
  6. * block-device to one or more other block-devices, either synchronous
  7. * or with an asynchronous completion notification.
  8. *
  9. * This file is released under the GPL.
  10. */
  11. #ifndef _LINUX_DM_KCOPYD_H
  12. #define _LINUX_DM_KCOPYD_H
  13. #ifdef __KERNEL__
  14. #include <linux/dm-io.h>
  15. /* FIXME: make this configurable */
  16. #define DM_KCOPYD_MAX_REGIONS 8
  17. #define DM_KCOPYD_IGNORE_ERROR 1
  18. #define DM_KCOPYD_WRITE_SEQ 2
  19. #define DM_KCOPYD_SNAP_MERGE 3
  20. struct dm_kcopyd_throttle {
  21. unsigned throttle;
  22. unsigned num_io_jobs;
  23. unsigned io_period;
  24. unsigned total_period;
  25. unsigned last_jiffies;
  26. };
  27. /*
  28. * kcopyd clients that want to support throttling must pass an initialised
  29. * dm_kcopyd_throttle struct into dm_kcopyd_client_create().
  30. * Two or more clients may share the same instance of this struct between
  31. * them if they wish to be throttled as a group.
  32. *
  33. * This macro also creates a corresponding module parameter to configure
  34. * the amount of throttling.
  35. */
  36. #define DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(name, description) \
  37. static struct dm_kcopyd_throttle dm_kcopyd_throttle = { 100, 0, 0, 0, 0 }; \
  38. module_param_named(name, dm_kcopyd_throttle.throttle, uint, 0644); \
  39. MODULE_PARM_DESC(name, description)
  40. /*
  41. * To use kcopyd you must first create a dm_kcopyd_client object.
  42. * throttle can be NULL if you don't want any throttling.
  43. */
  44. struct dm_kcopyd_client;
  45. struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle);
  46. void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc);
  47. /*
  48. * Submit a copy job to kcopyd. This is built on top of the
  49. * previous three fns.
  50. *
  51. * read_err is a boolean,
  52. * write_err is a bitset, with 1 bit for each destination region
  53. */
  54. typedef void (*dm_kcopyd_notify_fn)(int read_err, unsigned long write_err,
  55. void *context);
  56. void dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from,
  57. unsigned num_dests, struct dm_io_region *dests,
  58. unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  59. /*
  60. * Prepare a callback and submit it via the kcopyd thread.
  61. *
  62. * dm_kcopyd_prepare_callback allocates a callback structure and returns it.
  63. * It must not be called from interrupt context.
  64. * The returned value should be passed into dm_kcopyd_do_callback.
  65. *
  66. * dm_kcopyd_do_callback submits the callback.
  67. * It may be called from interrupt context.
  68. * The callback is issued from the kcopyd thread.
  69. */
  70. void *dm_kcopyd_prepare_callback(struct dm_kcopyd_client *kc,
  71. dm_kcopyd_notify_fn fn, void *context);
  72. void dm_kcopyd_do_callback(void *job, int read_err, unsigned long write_err);
  73. void dm_kcopyd_zero(struct dm_kcopyd_client *kc,
  74. unsigned num_dests, struct dm_io_region *dests,
  75. unsigned flags, dm_kcopyd_notify_fn fn, void *context);
  76. #endif /* __KERNEL__ */
  77. #endif /* _LINUX_DM_KCOPYD_H */