block: fix possible reorder of flush operations

[mirror_qemu.git] / block / io.c

diff --git a/block/io.c b/block/io.c
index 5c759fae470778b6ef1fda8757f439466ed67852..420944d80db104188445e198ce45eb890fc6edfb 100644 (file)
--- a/block/io.c
+++ b/block/io.c
@@ -1180,10 +1180,11 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
     int alignment = MAX(bs->bl.pwrite_zeroes_alignment,
                         bs->bl.request_alignment);
 
-    assert(is_power_of_2(alignment));
-    head = offset & (alignment - 1);
-    tail = (offset + count) & (alignment - 1);
-    max_write_zeroes &= ~(alignment - 1);
+    assert(alignment % bs->bl.request_alignment == 0);
+    head = offset % alignment;
+    tail = (offset + count) % alignment;
+    max_write_zeroes = QEMU_ALIGN_DOWN(max_write_zeroes, alignment);
+    assert(max_write_zeroes >= bs->bl.request_alignment);
 
     while (count > 0 && !ret) {
         int num = count;
@@ -2282,11 +2283,11 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
     int current_gen = bs->write_gen;
 
     /* Wait until any previous flushes are completed */
-    while (bs->flush_started_gen != bs->flushed_gen) {
+    while (bs->active_flush_req != NULL) {
         qemu_co_queue_wait(&bs->flush_queue);
     }
 
-    bs->flush_started_gen = current_gen;
+    bs->active_flush_req = &req;
 
     /* Write back all layers by calling one driver function */
     if (bs->drv->bdrv_co_flush) {
@@ -2356,7 +2357,9 @@ flush_parent:
 out:
     /* Notify any pending flushes that we have completed */
     bs->flushed_gen = current_gen;
-    qemu_co_queue_restart_all(&bs->flush_queue);
+    bs->active_flush_req = NULL;
+    /* Return value is ignored - it's ok if wait queue is empty */
+    qemu_co_queue_next(&bs->flush_queue);
 
     tracked_request_end(&req);
     return ret;
@@ -2423,16 +2426,16 @@ int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
         return 0;
     }
 
-    if (!bs->drv->bdrv_co_discard && !bs->drv->bdrv_aio_pdiscard) {
+    if (!bs->drv->bdrv_co_pdiscard && !bs->drv->bdrv_aio_pdiscard) {
         return 0;
     }
 
     /* Discard is advisory, so ignore any unaligned head or tail */
-    align = MAX(BDRV_SECTOR_SIZE,
-                MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment));
-    assert(is_power_of_2(align));
-    head = MIN(count, -offset & (align - 1));
+    align = MAX(bs->bl.pdiscard_alignment, bs->bl.request_alignment);
+    assert(align % bs->bl.request_alignment == 0);
+    head = offset % align;
     if (head) {
+        head = MIN(count, align - head);
         count -= head;
         offset += head;
     }
@@ -2450,14 +2453,14 @@ int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
 
     max_pdiscard = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_pdiscard, INT_MAX),
                                    align);
+    assert(max_pdiscard);
 
     while (count > 0) {
         int ret;
         int num = MIN(count, max_pdiscard);
 
-        if (bs->drv->bdrv_co_discard) {
-            ret = bs->drv->bdrv_co_discard(bs, offset >> BDRV_SECTOR_BITS,
-                                           num >> BDRV_SECTOR_BITS);
+        if (bs->drv->bdrv_co_pdiscard) {
+            ret = bs->drv->bdrv_co_pdiscard(bs, offset, num);
         } else {
             BlockAIOCB *acb;
             CoroutineIOCompletion co = {