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authorPeter Maydell <peter.maydell@linaro.org>2022-01-14 15:56:30 +0000
committerPeter Maydell <peter.maydell@linaro.org>2022-01-14 15:56:30 +0000
commit1cd2ad11d37c48f284f557954e1df675b126264c (patch)
tree09d75bcd7b586c4aa78cef09364e4020a573a8d4 /qemu-img.c
parent0b3f07ebf2954d28debd7493fef551152e08875b (diff)
parente5e748739562268ef4063ee77bf53ad7040b25c7 (diff)
downloadfocaccia-qemu-1cd2ad11d37c48f284f557954e1df675b126264c.tar.gz
focaccia-qemu-1cd2ad11d37c48f284f557954e1df675b126264c.zip
Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
Block layer patches

- qemu-storage-daemon: Add vhost-user-blk help
- block-backend: Fix use-after-free for BDS pointers after aio_poll()
- qemu-img: Fix sparseness of output image with unaligned ranges
- vvfat: Fix crashes in read-write mode
- Fix device deletion events with -device JSON syntax
- Code cleanups

# gpg: Signature made Fri 14 Jan 2022 13:50:16 GMT
# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  iotests/testrunner.py: refactor test_field_width
  block: drop BLK_PERM_GRAPH_MOD
  qemu-img: make is_allocated_sectors() more efficient
  iotests: Test qemu-img convert of zeroed data cluster
  vvfat: Fix vvfat_write() for writes before the root directory
  vvfat: Fix size of temporary qcow file
  iotests/308: Fix for CAP_DAC_OVERRIDE
  iotests/stream-error-on-reset: New test
  block-backend: prevent dangling BDS pointers across aio_poll()
  qapi/block: Restrict vhost-user-blk to CONFIG_VHOST_USER_BLK_SERVER
  qemu-storage-daemon: Add vhost-user-blk help
  docs: Correct 'vhost-user-blk' spelling
  softmmu: fix device deletion events with -device JSON syntax
  include/sysemu/blockdev.h: remove drive_get_max_devs
  include/sysemu/blockdev.h: remove drive_mark_claimed_by_board and inline drive_def
  block_int: make bdrv_backing_overridden static

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'qemu-img.c')
-rw-r--r--qemu-img.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/qemu-img.c b/qemu-img.c
index 21ba1e6800..6fe2466032 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1171,19 +1171,34 @@ static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum,
         }
     }
 
+    if (i == n) {
+        /*
+         * The whole buf is the same.
+         * No reason to split it into chunks, so return now.
+         */
+        *pnum = i;
+        return !is_zero;
+    }
+
     tail = (sector_num + i) & (alignment - 1);
     if (tail) {
         if (is_zero && i <= tail) {
-            /* treat unallocated areas which only consist
-             * of a small tail as allocated. */
+            /*
+             * For sure next sector after i is data, and it will rewrite this
+             * tail anyway due to RMW. So, let's just write data now.
+             */
             is_zero = false;
         }
         if (!is_zero) {
-            /* align up end offset of allocated areas. */
+            /* If possible, align up end offset of allocated areas. */
             i += alignment - tail;
             i = MIN(i, n);
         } else {
-            /* align down end offset of zero areas. */
+            /*
+             * For sure next sector after i is data, and it will rewrite this
+             * tail anyway due to RMW. Better is avoid RMW and write zeroes up
+             * to aligned bound.
+             */
             i -= tail;
         }
     }