Merge tag 'dm-3.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull dm update from Alasdair G Kergon:
 "Miscellaneous device-mapper fixes, cleanups and performance
  improvements.

  Of particular note:
   - Disable broken WRITE SAME support in all targets except linear and
     striped.  Use it when kcopyd is zeroing blocks.
   - Remove several mempools from targets by moving the data into the
     bio's new front_pad area(which dm calls 'per_bio_data').
   - Fix a race in thin provisioning if discards are misused.
   - Prevent userspace from interfering with the ioctl parameters and
     use kmalloc for the data buffer if it's small instead of vmalloc.
   - Throttle some annoying error messages when I/O fails."

* tag 'dm-3.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: (36 commits)
  dm stripe: add WRITE SAME support
  dm: remove map_info
  dm snapshot: do not use map_context
  dm thin: dont use map_context
  dm raid1: dont use map_context
  dm flakey: dont use map_context
  dm raid1: rename read_record to bio_record
  dm: move target request nr to dm_target_io
  dm snapshot: use per_bio_data
  dm verity: use per_bio_data
  dm raid1: use per_bio_data
  dm: introduce per_bio_data
  dm kcopyd: add WRITE SAME support to dm_kcopyd_zero
  dm linear: add WRITE SAME support
  dm: add WRITE SAME support
  dm: prepare to support WRITE SAME
  dm ioctl: use kmalloc if possible
  dm ioctl: remove PF_MEMALLOC
  dm persistent data: improve improve space map block alloc failure message
  dm thin: use DMERR_LIMIT for errors
  ...

1 files changed, 47 insertions, 8 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 38d27a10aa5..bf6afa2fc43 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -23,7 +23,6 @@ typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
 union map_info {
         void *ptr;
         unsigned long long ll;
-        unsigned target_request_nr;
 };
 
 /*
@@ -46,8 +45,7 @@ typedef void (*dm_dtr_fn) (struct dm_target *ti);
  * = 1: simple remap complete
  * = 2: The target wants to push back the io
  */
-typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
-                          union map_info *map_context);
+typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
                                   union map_info *map_context);
 
@@ -60,8 +58,7 @@ typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
  * 2   : The target wants to push back the io
  */
 typedef int (*dm_endio_fn) (struct dm_target *ti,
-                            struct bio *bio, int error,
-                            union map_info *map_context);
+                            struct bio *bio, int error);
 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
                                     struct request *clone, int error,
                                     union map_info *map_context);
@@ -193,18 +190,30 @@ struct dm_target {
          * A number of zero-length barrier requests that will be submitted
          * to the target for the purpose of flushing cache.
          *
-         * The request number will be placed in union map_info->target_request_nr.
+         * The request number can be accessed with dm_bio_get_target_request_nr.
          * It is a responsibility of the target driver to remap these requests
          * to the real underlying devices.
          */
         unsigned num_flush_requests;
 
         /*
-         * The number of discard requests that will be submitted to the
-         * target.  map_info->request_nr is used just like num_flush_requests.
+         * The number of discard requests that will be submitted to the target.
+         * The request number can be accessed with dm_bio_get_target_request_nr.
          */
         unsigned num_discard_requests;
 
+        /*
+         * The number of WRITE SAME requests that will be submitted to the target.
+         * The request number can be accessed with dm_bio_get_target_request_nr.
+         */
+        unsigned num_write_same_requests;
+
+        /*
+         * The minimum number of extra bytes allocated in each bio for the
+         * target to use.  dm_per_bio_data returns the data location.
+         */
+        unsigned per_bio_data_size;
+
         /* target specific data */
         void *private;
 
@@ -241,6 +250,36 @@ struct dm_target_callbacks {
         int (*congested_fn) (struct dm_target_callbacks *, int);
 };
 
+/*
+ * For bio-based dm.
+ * One of these is allocated for each bio.
+ * This structure shouldn't be touched directly by target drivers.
+ * It is here so that we can inline dm_per_bio_data and
+ * dm_bio_from_per_bio_data
+ */
+struct dm_target_io {
+        struct dm_io *io;
+        struct dm_target *ti;
+        union map_info info;
+        unsigned target_request_nr;
+        struct bio clone;
+};
+
+static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
+{
+        return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
+}
+
+static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
+{
+        return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
+}
+
+static inline unsigned dm_bio_get_target_request_nr(const struct bio *bio)
+{
+        return container_of(bio, struct dm_target_io, clone)->target_request_nr;
+}
+
 int dm_register_target(struct target_type *t);
 void dm_unregister_target(struct target_type *t);