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From: John Snow <jsnow@redhat.com>
To: qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, jsnow@redhat.com,
	qemu-stable@nongnu.org, qemu-block@nongnu.org,
	Max Reitz <mreitz@redhat.com>
Subject: [Qemu-devel] [PULL 29/36] block/backup: add backup_is_cluster_allocated
Date: Fri, 16 Aug 2019 19:13:11 -0400
Message-ID: <20190816231318.8650-30-jsnow@redhat.com> (raw)
In-Reply-To: <20190816231318.8650-1-jsnow@redhat.com>

Modify bdrv_is_unallocated_range to utilize the pnum return from
bdrv_is_allocated, and in the process change the semantics from
"is unallocated" to "is allocated."

Optionally returns a full number of clusters that share the same
allocation status.

This will be used to carefully toggle bits in the bitmap for sync=top
initialization in the following commits.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190716000117.25219-9-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
---
 block/backup.c | 62 +++++++++++++++++++++++++++++++++++---------------
 1 file changed, 44 insertions(+), 18 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 305f9b3468b..f6bf32c9438 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -185,6 +185,48 @@ static int coroutine_fn backup_cow_with_offload(BackupBlockJob *job,
     return nbytes;
 }
 
+/*
+ * Check if the cluster starting at offset is allocated or not.
+ * return via pnum the number of contiguous clusters sharing this allocation.
+ */
+static int backup_is_cluster_allocated(BackupBlockJob *s, int64_t offset,
+                                       int64_t *pnum)
+{
+    BlockDriverState *bs = blk_bs(s->common.blk);
+    int64_t count, total_count = 0;
+    int64_t bytes = s->len - offset;
+    int ret;
+
+    assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
+
+    while (true) {
+        ret = bdrv_is_allocated(bs, offset, bytes, &count);
+        if (ret < 0) {
+            return ret;
+        }
+
+        total_count += count;
+
+        if (ret || count == 0) {
+            /*
+             * ret: partial segment(s) are considered allocated.
+             * otherwise: unallocated tail is treated as an entire segment.
+             */
+            *pnum = DIV_ROUND_UP(total_count, s->cluster_size);
+            return ret;
+        }
+
+        /* Unallocated segment(s) with uncertain following segment(s) */
+        if (total_count >= s->cluster_size) {
+            *pnum = total_count / s->cluster_size;
+            return 0;
+        }
+
+        offset += count;
+        bytes -= count;
+    }
+}
+
 static int coroutine_fn backup_do_cow(BackupBlockJob *job,
                                       int64_t offset, uint64_t bytes,
                                       bool *error_is_read,
@@ -398,34 +440,18 @@ static bool coroutine_fn yield_and_check(BackupBlockJob *job)
     return false;
 }
 
-static bool bdrv_is_unallocated_range(BlockDriverState *bs,
-                                      int64_t offset, int64_t bytes)
-{
-    int64_t end = offset + bytes;
-
-    while (offset < end && !bdrv_is_allocated(bs, offset, bytes, &bytes)) {
-        if (bytes == 0) {
-            return true;
-        }
-        offset += bytes;
-        bytes = end - offset;
-    }
-
-    return offset >= end;
-}
-
 static int coroutine_fn backup_loop(BackupBlockJob *job)
 {
     bool error_is_read;
     int64_t offset;
     BdrvDirtyBitmapIter *bdbi;
-    BlockDriverState *bs = blk_bs(job->common.blk);
     int ret = 0;
+    int64_t dummy;
 
     bdbi = bdrv_dirty_iter_new(job->copy_bitmap);
     while ((offset = bdrv_dirty_iter_next(bdbi)) != -1) {
         if (job->sync_mode == MIRROR_SYNC_MODE_TOP &&
-            bdrv_is_unallocated_range(bs, offset, job->cluster_size))
+            !backup_is_cluster_allocated(job, offset, &dummy))
         {
             bdrv_reset_dirty_bitmap(job->copy_bitmap, offset,
                                     job->cluster_size);
-- 
2.21.0



  parent reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-16 23:12 [Qemu-devel] [PULL 00/36] Bitmaps patches John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 01/36] qapi/block-core: Introduce BackupCommon John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 02/36] drive-backup: create do_backup_common John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 03/36] blockdev-backup: utilize do_backup_common John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 04/36] qapi: add BitmapSyncMode enum John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 05/36] block/backup: Add mirror sync mode 'bitmap' John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 06/36] block/backup: add 'never' policy to bitmap sync mode John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 07/36] hbitmap: Fix merge when b is empty, and result is not an alias of a John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 08/36] hbitmap: enable merging across granularities John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 09/36] block/dirty-bitmap: add bdrv_dirty_bitmap_merge_internal John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 10/36] block/dirty-bitmap: add bdrv_dirty_bitmap_get John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 11/36] block/backup: upgrade copy_bitmap to BdrvDirtyBitmap John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 12/36] block/backup: add 'always' bitmap sync policy John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 13/36] iotests: add testing shim for script-style python tests John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 14/36] iotests: teach run_job to cancel pending jobs John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 15/36] iotests: teach FilePath to produce multiple paths John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 16/36] iotests: Add virtio-scsi device helper John Snow
2019-08-16 23:12 ` [Qemu-devel] [PULL 17/36] iotests: add test 257 for bitmap-mode backups John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 18/36] block/backup: loosen restriction on readonly bitmaps John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 19/36] blockdev: reduce aio_context locked sections in bitmap add/remove John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 20/36] qapi: implement block-dirty-bitmap-remove transaction action John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 21/36] iotests: test bitmap moving inside 254 John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 22/36] iotests/257: add Pattern class John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 23/36] iotests/257: add EmulatedBitmap class John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 24/36] iotests/257: Refactor backup helpers John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 25/36] block/backup: hoist bitmap check into QMP interface John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 26/36] iotests/257: test API failures John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 27/36] block/backup: improve sync=bitmap work estimates John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 28/36] block/backup: centralize copy_bitmap initialization John Snow
2019-08-16 23:13 ` John Snow [this message]
2019-08-16 23:13 ` [Qemu-devel] [PULL 30/36] block/backup: teach TOP to never copy unallocated regions John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 31/36] block/backup: support bitmap sync modes for non-bitmap backups John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 32/36] iotests/257: test traditional sync modes John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 33/36] qapi: add dirty-bitmaps to query-named-block-nodes result John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 34/36] block/backup: deal with zero detection John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 35/36] block/backup: refactor write_flags John Snow
2019-08-16 23:13 ` [Qemu-devel] [PULL 36/36] tests/test-hbitmap: test next_zero and _next_dirty_area after truncate John Snow
2019-08-19 11:32 ` [Qemu-devel] [PULL 00/36] Bitmaps patches Peter Maydell

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