block: Convert bdrv_co_discard() to byte-based

Another step towards byte-based interfaces everywhere.  Replace
the sector-based bdrv_co_discard() with a new byte-based
bdrv_co_pdiscard(), which silently ignores any unaligned head
or tail.  Driver callbacks will be converted in followup patches.

By calculating the alignment outside of the loop, and clamping
the max discard to an aligned value, we can simplify the actions
done within the loop.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-2-git-send-email-eblake@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/block/blkreplay.c b/block/blkreplay.c
index 3368c8c98ddf4b4a53d0f1cf0e204941a2e99717..c69e5a57a054224eb6e3f4231e696558ab364834 100755 (executable)
--- a/block/blkreplay.c
+++ b/block/blkreplay.c
@@ -118,7 +118,8 @@ static int coroutine_fn blkreplay_co_discard(BlockDriverState *bs,
     int64_t sector_num, int nb_sectors)
 {
     uint64_t reqid = request_id++;
-    int ret = bdrv_co_discard(bs->file->bs, sector_num, nb_sectors);
+    int ret = bdrv_co_pdiscard(bs->file->bs, sector_num << BDRV_SECTOR_BITS,
+                               nb_sectors << BDRV_SECTOR_BITS);
     block_request_create(reqid, bs, qemu_coroutine_self());
     qemu_coroutine_yield();
 

diff --git a/block/block-backend.c b/block/block-backend.c
index f9cea1b304f2745d7c2b946a1d8e3b01e8b413d4..d982cf9d291584411141608272a282494355e42f 100644 (file)
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1113,7 +1113,8 @@ int blk_co_discard(BlockBackend *blk, int64_t sector_num, int nb_sectors)
         return ret;
     }
 
-    return bdrv_co_discard(blk_bs(blk), sector_num, nb_sectors);
+    return bdrv_co_pdiscard(blk_bs(blk), sector_num << BDRV_SECTOR_BITS,
+                            nb_sectors << BDRV_SECTOR_BITS);
 }
 
 int blk_co_flush(BlockBackend *blk)

diff --git a/block/io.c b/block/io.c
index 410394dc4235d7c933e8e459996e6bc476e57cd4..14d448d50c6eb2459fdabe62cac90f3c07e11e85 100644 (file)
--- a/block/io.c
+++ b/block/io.c
@@ -2199,7 +2199,8 @@ static void coroutine_fn bdrv_aio_discard_co_entry(void *opaque)
     BlockAIOCBCoroutine *acb = opaque;
     BlockDriverState *bs = acb->common.bs;
 
-    acb->req.error = bdrv_co_discard(bs, acb->req.sector, acb->req.nb_sectors);
+    acb->req.error = bdrv_co_pdiscard(bs, acb->req.sector << BDRV_SECTOR_BITS,
+                                      acb->req.nb_sectors << BDRV_SECTOR_BITS);
     bdrv_co_complete(acb);
 }
 
@@ -2398,20 +2399,22 @@ static void coroutine_fn bdrv_discard_co_entry(void *opaque)
 {
     DiscardCo *rwco = opaque;
 
-    rwco->ret = bdrv_co_discard(rwco->bs, rwco->sector_num, rwco->nb_sectors);
+    rwco->ret = bdrv_co_pdiscard(rwco->bs, rwco->sector_num << BDRV_SECTOR_BITS,
+                                 rwco->nb_sectors << BDRV_SECTOR_BITS);
 }
 
-int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
-                                 int nb_sectors)
+int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
+                                  int count)
 {
     BdrvTrackedRequest req;
-    int max_discard, ret;
+    int max_pdiscard, ret;
+    int head, align;
 
     if (!bs->drv) {
         return -ENOMEDIUM;
     }
 
-    ret = bdrv_check_request(bs, sector_num, nb_sectors);
+    ret = bdrv_check_byte_request(bs, offset, count);
     if (ret < 0) {
         return ret;
     } else if (bs->read_only) {
@@ -2428,45 +2431,45 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
         return 0;
     }
 
-    tracked_request_begin(&req, bs, sector_num << BDRV_SECTOR_BITS,
-                          nb_sectors << BDRV_SECTOR_BITS, BDRV_TRACKED_DISCARD);
+    /* 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));
+    if (head) {
+        count -= head;
+        offset += head;
+    }
+    count = QEMU_ALIGN_DOWN(count, align);
+    if (!count) {
+        return 0;
+    }
+
+    tracked_request_begin(&req, bs, offset, count, BDRV_TRACKED_DISCARD);
 
     ret = notifier_with_return_list_notify(&bs->before_write_notifiers, &req);
     if (ret < 0) {
         goto out;
     }
 
-    max_discard = MIN_NON_ZERO(bs->bl.max_pdiscard >> BDRV_SECTOR_BITS,
-                               BDRV_REQUEST_MAX_SECTORS);
-    while (nb_sectors > 0) {
-        int ret;
-        int num = nb_sectors;
-        int discard_alignment = bs->bl.pdiscard_alignment >> BDRV_SECTOR_BITS;
-
-        /* align request */
-        if (discard_alignment &&
-            num >= discard_alignment &&
-            sector_num % discard_alignment) {
-            if (num > discard_alignment) {
-                num = discard_alignment;
-            }
-            num -= sector_num % discard_alignment;
-        }
+    max_pdiscard = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_pdiscard, INT_MAX),
+                                   align);
 
-        /* limit request size */
-        if (num > max_discard) {
-            num = max_discard;
-        }
+    while (count > 0) {
+        int ret;
+        int num = MIN(count, max_pdiscard);
 
         if (bs->drv->bdrv_co_discard) {
-            ret = bs->drv->bdrv_co_discard(bs, sector_num, num);
+            ret = bs->drv->bdrv_co_discard(bs, offset >> BDRV_SECTOR_BITS,
+                                           num >> BDRV_SECTOR_BITS);
         } else {
             BlockAIOCB *acb;
             CoroutineIOCompletion co = {
                 .coroutine = qemu_coroutine_self(),
             };
 
-            acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors,
+            acb = bs->drv->bdrv_aio_discard(bs, offset >> BDRV_SECTOR_BITS,
+                                            num >> BDRV_SECTOR_BITS,
                                             bdrv_co_io_em_complete, &co);
             if (acb == NULL) {
                 ret = -EIO;
@@ -2480,8 +2483,8 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
             goto out;
         }
 
-        sector_num += num;
-        nb_sectors -= num;
+        offset += num;
+        count -= num;
     }
     ret = 0;
 out:

diff --git a/block/raw_bsd.c b/block/raw_bsd.c
index d7674132f287ea057a39971173d5975886a2bb7a..68f0a91a9afd781d099fdad730082f6ac8f94f6e 100644 (file)
--- a/block/raw_bsd.c
+++ b/block/raw_bsd.c
@@ -137,7 +137,8 @@ static int coroutine_fn raw_co_pwrite_zeroes(BlockDriverState *bs,
 static int coroutine_fn raw_co_discard(BlockDriverState *bs,
                                        int64_t sector_num, int nb_sectors)
 {
-    return bdrv_co_discard(bs->file->bs, sector_num, nb_sectors);
+    return bdrv_co_pdiscard(bs->file->bs, sector_num << BDRV_SECTOR_BITS,
+                            nb_sectors << BDRV_SECTOR_BITS);
 }
 
 static int64_t raw_getlength(BlockDriverState *bs)

diff --git a/include/block/block.h b/include/block/block.h
index 616d8b9f1219084bbbdec92b6dee87298e7a009f..4f5cebf15fd5707f2bcf5d7c8bc8e27f0436d99a 100644 (file)
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -342,7 +342,7 @@ void coroutine_fn bdrv_co_drain(BlockDriverState *bs);
 void bdrv_drain_all(void);
 
 int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
-int bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
+int bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset, int count);
 int bdrv_has_zero_init_1(BlockDriverState *bs);
 int bdrv_has_zero_init(BlockDriverState *bs);
 bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs);