From 070f95bad47e0d0f1884b93184369b3c9322cd4c Mon Sep 17 00:00:00 2001

Message-Id: <070f95bad47e0d0f1884b93184369b3c9322cd4c.1389014116.git.minovotn@redhat.com>

In-Reply-To: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>

References: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Mon, 9 Dec 2013 14:09:37 +0100

Subject: [PATCH 49/50] qemu-img: round down request length to an aligned

 sector

RH-Author: Paolo Bonzini <pbonzini@redhat.com>

Message-id: <1386598178-11845-52-git-send-email-pbonzini@redhat.com>

Patchwork-id: 56088

O-Subject: [RHEL 7.0 qemu-kvm PATCH 51/52] qemu-img: round down request length to an aligned sector

Bugzilla: 1039557

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

From: Peter Lieven <pl@kamp.de>

this patch shortens requests to end at an aligned sector so that

the next request starts aligned.

[Squashed Peter's fix for bdrv_get_info() failure discussed on the

mailing list.

--Stefan]

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Peter Lieven <pl@kamp.de>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit 24f833cd43dbfb5f8ae99e8a6d3691671622d3ea)

---

 qemu-img.c | 32 ++++++++++++++++++++++++--------

 1 file changed, 24 insertions(+), 8 deletions(-)

Signed-off-by: Michal Novotny <minovotn@redhat.com>

---

 qemu-img.c | 32 ++++++++++++++++++++++++--------

 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c

index 6890bb1..55bb82c 100644

--- a/qemu-img.c

+++ b/qemu-img.c

@@ -1122,8 +1122,7 @@ out3:

 static int img_convert(int argc, char **argv)

 {

-    int c, n, n1, bs_n, bs_i, compress, cluster_size,

-        cluster_sectors, skip_create;

+    int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create;

     int64_t ret = 0;

     int progress = 0, flags;

     const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename;

@@ -1395,19 +1394,23 @@ static int img_convert(int argc, char **argv)

         }

     }

-    if (compress) {

-        ret = bdrv_get_info(out_bs, &bdi;;

-        if (ret < 0) {

+    cluster_sectors = 0;

+    ret = bdrv_get_info(out_bs, &bdi;;

+    if (ret < 0) {

+        if (compress) {

             error_report("could not get block driver info");

             goto out;

         }

-        cluster_size = bdi.cluster_size;

-        if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE) {

+    } else {

+        cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;

+    }

+

+    if (compress) {

+        if (cluster_sectors <= 0 || cluster_sectors > bufsectors) {

             error_report("invalid cluster size");

             ret = -1;

             goto out;

         }

-        cluster_sectors = cluster_size >> 9;

         sector_num = 0;

         nb_sectors = total_sectors;

@@ -1540,6 +1543,19 @@ static int img_convert(int argc, char **argv)

             }

             n = MIN(nb_sectors, bufsectors);

+

+            /* round down request length to an aligned sector, but

+             * do not bother doing this on short requests. They happen

+             * when we found an all-zero area, and the next sector to

+             * write will not be sector_num + n. */

+            if (cluster_sectors > 0 && n >= cluster_sectors) {

+                int64_t next_aligned_sector = (sector_num + n);

+                next_aligned_sector -= next_aligned_sector % cluster_sectors;

+                if (sector_num + n > next_aligned_sector) {

+                    n = next_aligned_sector - sector_num;

+                }

+            }

+

             n = MIN(n, bs_sectors - (sector_num - bs_offset));

             n1 = n;

-- 

1.7.11.7