1 files changed, 32 insertions, 17 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index bf6afa2fc432..1e483fa7afb4 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -68,8 +68,8 @@ typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
 typedef int (*dm_preresume_fn) (struct dm_target *ti);
 typedef void (*dm_resume_fn) (struct dm_target *ti);
 
-typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
-                             unsigned status_flags, char *result, unsigned maxlen);
+typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
+                              unsigned status_flags, char *result, unsigned maxlen);
 
 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
 
@@ -175,6 +175,14 @@ struct target_type {
 #define DM_TARGET_IMMUTABLE             0x00000004
 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 
+/*
+ * Some targets need to be sent the same WRITE bio severals times so
+ * that they can send copies of it to different devices.  This function
+ * examines any supplied bio and returns the number of copies of it the
+ * target requires.
+ */
+typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
+
 struct dm_target {
         struct dm_table *table;
         struct target_type *type;
@@ -187,26 +195,26 @@ struct dm_target {
         uint32_t max_io_len;
 
         /*
-         * A number of zero-length barrier requests that will be submitted
+         * A number of zero-length barrier bios that will be submitted
          * to the target for the purpose of flushing cache.
          *
-         * 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
+         * The bio number can be accessed with dm_bio_get_target_bio_nr.
+         * It is a responsibility of the target driver to remap these bios
          * to the real underlying devices.
          */
-        unsigned num_flush_requests;
+        unsigned num_flush_bios;
 
         /*
-         * 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.
+         * The number of discard bios that will be submitted to the target.
+         * The bio number can be accessed with dm_bio_get_target_bio_nr.
          */
-        unsigned num_discard_requests;
+        unsigned num_discard_bios;
 
         /*
-         * 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.
+         * The number of WRITE SAME bios that will be submitted to the target.
+         * The bio number can be accessed with dm_bio_get_target_bio_nr.
          */
-        unsigned num_write_same_requests;
+        unsigned num_write_same_bios;
 
         /*
          * The minimum number of extra bytes allocated in each bio for the
@@ -214,6 +222,13 @@ struct dm_target {
          */
         unsigned per_bio_data_size;
 
+        /*
+         * If defined, this function is called to find out how many
+         * duplicate bios should be sent to the target when writing
+         * data.
+         */
+        dm_num_write_bios_fn num_write_bios;
+
         /* target specific data */
         void *private;
 
@@ -233,10 +248,10 @@ struct dm_target {
         bool discards_supported:1;
 
         /*
-         * Set if the target required discard request to be split
+         * Set if the target required discard bios to be split
          * on max_io_len boundary.
          */
-        bool split_discard_requests:1;
+        bool split_discard_bios:1;
 
         /*
          * Set if this target does not return zeroes on discarded blocks.
@@ -261,7 +276,7 @@ struct dm_target_io {
         struct dm_io *io;
         struct dm_target *ti;
         union map_info info;
-        unsigned target_request_nr;
+        unsigned target_bio_nr;
         struct bio clone;
 };
 
@@ -275,9 +290,9 @@ 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)
+static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 {
-        return container_of(bio, struct dm_target_io, clone)->target_request_nr;
+        return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 }
 
 int dm_register_target(struct target_type *t);