xen-blkif: drop struct blkif_request_segment_aligned

This was wrongly introduced in commit 402b27f9, the only difference
between blkif_request_segment_aligned and blkif_request_segment is
that the former has a named padding, while both share the same
memory layout.

Also correct a few minor glitches in the description, including for it
to no longer assume PAGE_SIZE == 4096.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
[Description fix by Jan Beulich]
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reported-by: Jan Beulich <jbeulich@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Matt Rushton <mrushton@amazon.com>
Cc: Matt Wilson <msw@amazon.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

4 files changed, 19 insertions, 25 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 394fa2eabf87..e612627ae981 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -847,7 +847,7 @@ static int xen_blkbk_parse_indirect(struct blkif_request *req,
         struct grant_page **pages = pending_req->indirect_pages;
         struct xen_blkif *blkif = pending_req->blkif;
         int indirect_grefs, rc, n, nseg, i;
-        struct blkif_request_segment_aligned *segments = NULL;
+        struct blkif_request_segment *segments = NULL;
 
         nseg = pending_req->nr_pages;
         indirect_grefs = INDIRECT_PAGES(nseg);
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index e40326a7f707..9eb34e24b4fe 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -57,7 +57,7 @@
 #define MAX_INDIRECT_SEGMENTS 256
 
 #define SEGS_PER_INDIRECT_FRAME \
-        (PAGE_SIZE/sizeof(struct blkif_request_segment_aligned))
+        (PAGE_SIZE/sizeof(struct blkif_request_segment))
 #define MAX_INDIRECT_PAGES \
         ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
 #define INDIRECT_PAGES(_segs) \
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index c4a4c9006288..7d09dfc9735c 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -162,7 +162,7 @@ static DEFINE_SPINLOCK(minor_lock);
 #define DEV_NAME        "xvd"   /* name in /dev */
 
 #define SEGS_PER_INDIRECT_FRAME \
-        (PAGE_SIZE/sizeof(struct blkif_request_segment_aligned))
+        (PAGE_SIZE/sizeof(struct blkif_request_segment))
 #define INDIRECT_GREFS(_segs) \
         ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
 
@@ -393,7 +393,7 @@ static int blkif_queue_request(struct request *req)
         unsigned long id;
         unsigned int fsect, lsect;
         int i, ref, n;
-        struct blkif_request_segment_aligned *segments = NULL;
+        struct blkif_request_segment *segments = NULL;
 
         /*
          * Used to store if we are able to queue the request by just using
@@ -550,7 +550,7 @@ static int blkif_queue_request(struct request *req)
                         } else {
                                 n = i % SEGS_PER_INDIRECT_FRAME;
                                 segments[n] =
-                                        (struct blkif_request_segment_aligned) {
+                                        (struct blkif_request_segment) {
                                                         .gref       = ref,
                                                         .first_sect = fsect,
                                                         .last_sect  = lsect };
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index ae665ac59c36..32ec05a6572f 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -113,13 +113,13 @@ typedef uint64_t blkif_sector_t;
  * it's less than the number provided by the backend. The indirect_grefs field
  * in blkif_request_indirect should be filled by the frontend with the
  * grant references of the pages that are holding the indirect segments.
- * This pages are filled with an array of blkif_request_segment_aligned
- * that hold the information about the segments. The number of indirect
- * pages to use is determined by the maximum number of segments
- * a indirect request contains. Every indirect page can contain a maximum
- * of 512 segments (PAGE_SIZE/sizeof(blkif_request_segment_aligned)),
- * so to calculate the number of indirect pages to use we have to do
- * ceil(indirect_segments/512).
+ * These pages are filled with an array of blkif_request_segment that hold the
+ * information about the segments. The number of indirect pages to use is
+ * determined by the number of segments an indirect request contains. Every
+ * indirect page can contain a maximum of
+ * (PAGE_SIZE / sizeof(struct blkif_request_segment)) segments, so to
+ * calculate the number of indirect pages to use we have to do
+ * ceil(indirect_segments / (PAGE_SIZE / sizeof(struct blkif_request_segment))).
  *
  * If a backend does not recognize BLKIF_OP_INDIRECT, it should *not*
  * create the "feature-max-indirect-segments" node!
@@ -135,13 +135,12 @@ typedef uint64_t blkif_sector_t;
 
 #define BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST 8
 
-struct blkif_request_segment_aligned {
-        grant_ref_t gref;        /* reference to I/O buffer frame        */
-        /* @first_sect: first sector in frame to transfer (inclusive).   */
-        /* @last_sect: last sector in frame to transfer (inclusive).     */
-        uint8_t     first_sect, last_sect;
-        uint16_t    _pad; /* padding to make it 8 bytes, so it's cache-aligned */
-} __attribute__((__packed__));
+struct blkif_request_segment {
+                grant_ref_t gref;        /* reference to I/O buffer frame        */
+                /* @first_sect: first sector in frame to transfer (inclusive).   */
+                /* @last_sect: last sector in frame to transfer (inclusive).     */
+                uint8_t     first_sect, last_sect;
+};
 
 struct blkif_request_rw {
         uint8_t        nr_segments;  /* number of segments                   */
@@ -151,12 +150,7 @@ struct blkif_request_rw {
 #endif
         uint64_t       id;           /* private guest value, echoed in resp  */
         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
-        struct blkif_request_segment {
-                grant_ref_t gref;        /* reference to I/O buffer frame        */
-                /* @first_sect: first sector in frame to transfer (inclusive).   */
-                /* @last_sect: last sector in frame to transfer (inclusive).     */
-                uint8_t     first_sect, last_sect;
-        } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+        struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 } __attribute__((__packed__));
 
 struct blkif_request_discard {