From 971e56af33f89b4e11a2e6b07b389d729756b9ed Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Tue, 3 Dec 2013 14:55:55 +0100

Subject: [PATCH 17/37] block: Allow waiting for overlapping requests between begin/end

Message-id: <1392117622-28812-18-git-send-email-kwolf@redhat.com>

Patchwork-id: 57182

O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 17/37] block: Allow waiting for overlapping requests between begin/end

Bugzilla: 748906

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Max Reitz <mreitz@redhat.com>

Previously, it was not possible to use wait_for_overlapping_requests()

between tracked_request_begin()/end() because it would wait for itself.

Ignore the current request in the overlap check and run more of the

bdrv_co_do_preadv/pwritev code with a BdrvTrackedRequest present.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

Reviewed-by: Benoit Canet <benoit@irqsave.net>

(cherry picked from commit 65afd211c71fc91750d8a18f9604c1e57a5202fb)

Conflicts:

	block.c

Conflicts because in RHEL 7 write notifiers don't exist.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

 block.c | 36 +++++++++++++++++++-----------------

 1 file changed, 19 insertions(+), 17 deletions(-)

---

 block.c |   36 +++++++++++++++++++-----------------

 1 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/block.c b/block.c

index 09bb127..645bcd0 100644

--- a/block.c

+++ b/block.c

@@ -2129,7 +2129,7 @@ static bool tracked_request_overlaps(BdrvTrackedRequest *req,

 }

 static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,

-        int64_t offset, unsigned int bytes)

+        BdrvTrackedRequest *self, int64_t offset, unsigned int bytes)

 {

     BdrvTrackedRequest *req;

     int64_t cluster_offset;

@@ -2147,6 +2147,9 @@ static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,

     do {

         retry = false;

         QLIST_FOREACH(req, &bs->tracked_requests, list) {

+            if (req == self) {

+                continue;

+            }

             if (tracked_request_overlaps(req, cluster_offset, cluster_bytes)) {

                 /* Hitting this means there was a reentrant request, for

                  * example, a block driver issuing nested requests.  This must

@@ -2744,10 +2747,10 @@ err:

  * implemented by the caller.

  */

 static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,

-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)

+    BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,

+    QEMUIOVector *qiov, int flags)

 {

     BlockDriver *drv = bs->drv;

-    BdrvTrackedRequest req;

     int ret;

     int64_t sector_num = offset >> BDRV_SECTOR_BITS;

@@ -2762,11 +2765,9 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,

     }

     if (bs->copy_on_read_in_flight) {

-        wait_for_overlapping_requests(bs, offset, bytes);

+        wait_for_overlapping_requests(bs, req, offset, bytes);

     }

-    tracked_request_begin(&req, bs, offset, bytes, false);

-

     if (flags & BDRV_REQ_COPY_ON_READ) {

         int pnum;

@@ -2813,8 +2814,6 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,

     }

 out:

-    tracked_request_end(&req;;

-

     if (flags & BDRV_REQ_COPY_ON_READ) {

         bs->copy_on_read_in_flight--;

     }

@@ -2830,6 +2829,8 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,

     BdrvRequestFlags flags)

 {

     BlockDriver *drv = bs->drv;

+    BdrvTrackedRequest req;

+

     /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */

     uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);

     uint8_t *head_buf = NULL;

@@ -2880,9 +2881,11 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,

         bytes = ROUND_UP(bytes, align);

     }

-    ret = bdrv_aligned_preadv(bs, offset, bytes,

+    tracked_request_begin(&req, bs, offset, bytes, false);

+    ret = bdrv_aligned_preadv(bs, &req, offset, bytes,

                               use_local_qiov ? &local_qiov : qiov,

                               flags);

+    tracked_request_end(&req;;

     if (use_local_qiov) {

         qemu_iovec_destroy(&local_qiov);

@@ -3001,10 +3004,10 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,

  * Forwards an already correctly aligned write request to the BlockDriver.

  */

 static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,

-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)

+    BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,

+    QEMUIOVector *qiov, int flags)

 {

     BlockDriver *drv = bs->drv;

-    BdrvTrackedRequest req;

     int ret;

     int64_t sector_num = offset >> BDRV_SECTOR_BITS;

@@ -3014,11 +3017,9 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,

     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);

     if (bs->copy_on_read_in_flight) {

-        wait_for_overlapping_requests(bs, offset, bytes);

+        wait_for_overlapping_requests(bs, req, offset, bytes);

     }

-    tracked_request_begin(&req, bs, offset, bytes, true);

-

     if (flags & BDRV_REQ_ZERO_WRITE) {

         ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors, flags);

     } else {

@@ -3040,8 +3041,6 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,

         bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);

     }

-    tracked_request_end(&req;;

-

     return ret;

 }

@@ -3052,6 +3051,7 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,

     int64_t offset, unsigned int bytes, QEMUIOVector *qiov,

     BdrvRequestFlags flags)

 {

+    BdrvTrackedRequest req;

     int ret;

     if (!bs->drv) {

@@ -3070,7 +3070,9 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,

         bdrv_io_limits_intercept(bs, true, bytes >> BDRV_SECTOR_BITS);

     }

-    ret = bdrv_aligned_pwritev(bs, offset, bytes, qiov, flags);

+    tracked_request_begin(&req, bs, offset, bytes, true);

+    ret = bdrv_aligned_pwritev(bs, &req, offset, bytes, qiov, flags);

+    tracked_request_end(&req;;

     return ret;

 }

-- 

1.7.1