[PATCH] Document bi_sector and sector_t

Signed-Off-By: Roger Gammans <rgammans@computer-surgery.co.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 711c321a7011..092dbd0e7658 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -70,7 +70,8 @@ typedef void (bio_destructor_t) (struct bio *);
  * stacking drivers)
  */
 struct bio {
-        sector_t                bi_sector;
+        sector_t                bi_sector;      /* device address in 512 byte
+                                                   sectors */
         struct bio              *bi_next;       /* request queue link */
         struct block_device     *bi_bdev;
         unsigned long           bi_flags;       /* status, command, etc */
diff --git a/include/linux/types.h b/include/linux/types.h
index 406d4ae57631..750f085fa564 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -129,8 +129,12 @@ typedef		__s64		int64_t;
 /* this is a special 64bit data type that is 8-byte aligned */
 #define aligned_u64 unsigned long long __attribute__((aligned(8)))
 
-/*
+/**
  * The type used for indexing onto a disc or disc partition.
+ *
+ * Linux always considers sectors to be 512 bytes long independently
+ * of the devices real block size.
+ *
  * If required, asm/types.h can override it and define
  * HAVE_SECTOR_T
  */