[Qemu-devel] [PATCH] Fix block migration when the device size is not a multiple of 1 MB

[Pierre Riteau <Pierre.Riteau@irisa.fr>]

b02bea3a85cc939f09aa674a3f1e4f36d418c007 added a check on the return
value of bdrv_write and aborts migration when it fails. However, if the
size of the block device to migrate is not a multiple of BLOCK_SIZE
(currently 1 MB), the last bdrv_write will fail with -EIO.

Fixed by calling bdrv_write with the correct size of the last block.
---
 block-migration.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/block-migration.c b/block-migration.c
index 1475325..eeb9c62 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -635,6 +635,8 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
     int64_t addr;
     BlockDriverState *bs;
     uint8_t *buf;
+    int64_t total_sectors;
+    int nr_sectors;
 
     do {
         addr = qemu_get_be64(f);
@@ -656,10 +658,22 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
                 return -EINVAL;
             }
 
+            total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+            if (total_sectors <= 0) {
+                fprintf(stderr, "Error getting length of block device %s\n", device_name);
+                return -EINVAL;
+            }
+
+            if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
+                nr_sectors = total_sectors - addr;
+            } else {
+                nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
+            }
+
             buf = qemu_malloc(BLOCK_SIZE);
 
             qemu_get_buffer(f, buf, BLOCK_SIZE);
-            ret = bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);
+            ret = bdrv_write(bs, addr, buf, nr_sectors);
 
             qemu_free(buf);
             if (ret < 0) {
-- 
1.7.3.5