Blame SOURCES/kvm-block-Allow-waiting-for-overlapping-requests-between.patch

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From 971e56af33f89b4e11a2e6b07b389d729756b9ed Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Tue, 3 Dec 2013 14:55:55 +0100
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Subject: [PATCH 17/37] block: Allow waiting for overlapping requests between begin/end
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Message-id: <1392117622-28812-18-git-send-email-kwolf@redhat.com>
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Patchwork-id: 57182
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O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 17/37] block: Allow waiting for overlapping requests between begin/end
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Bugzilla: 748906
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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Previously, it was not possible to use wait_for_overlapping_requests()
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between tracked_request_begin()/end() because it would wait for itself.
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Ignore the current request in the overlap check and run more of the
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bdrv_co_do_preadv/pwritev code with a BdrvTrackedRequest present.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Benoit Canet <benoit@irqsave.net>
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(cherry picked from commit 65afd211c71fc91750d8a18f9604c1e57a5202fb)
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Conflicts:
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	block.c
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Conflicts because in RHEL 7 write notifiers don't exist.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block.c | 36 +++++++++++++++++++-----------------
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 1 file changed, 19 insertions(+), 17 deletions(-)
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---
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 block.c |   36 +++++++++++++++++++-----------------
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 1 files changed, 19 insertions(+), 17 deletions(-)
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diff --git a/block.c b/block.c
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index 09bb127..645bcd0 100644
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--- a/block.c
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+++ b/block.c
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@@ -2129,7 +2129,7 @@ static bool tracked_request_overlaps(BdrvTrackedRequest *req,
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 }
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 static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,
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-        int64_t offset, unsigned int bytes)
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+        BdrvTrackedRequest *self, int64_t offset, unsigned int bytes)
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 {
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     BdrvTrackedRequest *req;
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     int64_t cluster_offset;
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@@ -2147,6 +2147,9 @@ static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,
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     do {
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         retry = false;
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         QLIST_FOREACH(req, &bs->tracked_requests, list) {
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+            if (req == self) {
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+                continue;
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+            }
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             if (tracked_request_overlaps(req, cluster_offset, cluster_bytes)) {
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                 /* Hitting this means there was a reentrant request, for
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                  * example, a block driver issuing nested requests.  This must
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@@ -2744,10 +2747,10 @@ err:
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  * implemented by the caller.
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  */
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 static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
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-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)
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+    BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
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+    QEMUIOVector *qiov, int flags)
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 {
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     BlockDriver *drv = bs->drv;
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-    BdrvTrackedRequest req;
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     int ret;
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     int64_t sector_num = offset >> BDRV_SECTOR_BITS;
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@@ -2762,11 +2765,9 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
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     }
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     if (bs->copy_on_read_in_flight) {
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-        wait_for_overlapping_requests(bs, offset, bytes);
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+        wait_for_overlapping_requests(bs, req, offset, bytes);
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     }
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-    tracked_request_begin(&req, bs, offset, bytes, false);
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-
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     if (flags & BDRV_REQ_COPY_ON_READ) {
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         int pnum;
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@@ -2813,8 +2814,6 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
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     }
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 out:
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-    tracked_request_end(&req);
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-
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     if (flags & BDRV_REQ_COPY_ON_READ) {
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         bs->copy_on_read_in_flight--;
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     }
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@@ -2830,6 +2829,8 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
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     BdrvRequestFlags flags)
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 {
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     BlockDriver *drv = bs->drv;
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+    BdrvTrackedRequest req;
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+
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     /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
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     uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment);
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     uint8_t *head_buf = NULL;
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@@ -2880,9 +2881,11 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
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         bytes = ROUND_UP(bytes, align);
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     }
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-    ret = bdrv_aligned_preadv(bs, offset, bytes,
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+    tracked_request_begin(&req, bs, offset, bytes, false);
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+    ret = bdrv_aligned_preadv(bs, &req, offset, bytes,
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                               use_local_qiov ? &local_qiov : qiov,
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                               flags);
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+    tracked_request_end(&req);
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     if (use_local_qiov) {
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         qemu_iovec_destroy(&local_qiov);
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@@ -3001,10 +3004,10 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
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  * Forwards an already correctly aligned write request to the BlockDriver.
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  */
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 static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
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-    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)
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+    BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
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+    QEMUIOVector *qiov, int flags)
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 {
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     BlockDriver *drv = bs->drv;
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-    BdrvTrackedRequest req;
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     int ret;
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     int64_t sector_num = offset >> BDRV_SECTOR_BITS;
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@@ -3014,11 +3017,9 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
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     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
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     if (bs->copy_on_read_in_flight) {
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-        wait_for_overlapping_requests(bs, offset, bytes);
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+        wait_for_overlapping_requests(bs, req, offset, bytes);
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     }
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-    tracked_request_begin(&req, bs, offset, bytes, true);
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-
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     if (flags & BDRV_REQ_ZERO_WRITE) {
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         ret = bdrv_co_do_write_zeroes(bs, sector_num, nb_sectors, flags);
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     } else {
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@@ -3040,8 +3041,6 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
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         bs->total_sectors = MAX(bs->total_sectors, sector_num + nb_sectors);
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     }
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-    tracked_request_end(&req);
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-
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     return ret;
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 }
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@@ -3052,6 +3051,7 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
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     int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
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     BdrvRequestFlags flags)
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 {
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+    BdrvTrackedRequest req;
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     int ret;
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     if (!bs->drv) {
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@@ -3070,7 +3070,9 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
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         bdrv_io_limits_intercept(bs, true, bytes >> BDRV_SECTOR_BITS);
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     }
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-    ret = bdrv_aligned_pwritev(bs, offset, bytes, qiov, flags);
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+    tracked_request_begin(&req, bs, offset, bytes, true);
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+    ret = bdrv_aligned_pwritev(bs, &req, offset, bytes, qiov, flags);
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+    tracked_request_end(&req);
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     return ret;
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 }
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-- 
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1.7.1
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