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Blame SOURCES/kvm-raw-posix-implement-write_zeroes-with-MAY_UNMAP-for-.patch.patch.patch.patch.patch

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From f1b8961cbef828b62ba1ca7da79cd516f7dfc52b Mon Sep 17 00:00:00 2001
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Message-Id: <f1b8961cbef828b62ba1ca7da79cd516f7dfc52b.1389014116.git.minovotn@redhat.com>
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In-Reply-To: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>
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References: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 9 Dec 2013 14:09:28 +0100
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Subject: [PATCH 40/50] raw-posix: implement write_zeroes with MAY_UNMAP for
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 block devices
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: <1386598178-11845-43-git-send-email-pbonzini@redhat.com>
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Patchwork-id: 56079
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O-Subject: [RHEL 7.0 qemu-kvm PATCH 42/52] raw-posix: implement write_zeroes with MAY_UNMAP for block devices
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Bugzilla: 1007815
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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See the next commit for the description of the Linux kernel problem
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that is worked around in raw_open_common.
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit d0b4503ed2d8713791c38839341b023f78d1a3d9)
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---
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 block/raw-posix.c | 37 +++++++++++++++++++++++++++++++++++++
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 1 file changed, 37 insertions(+)
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Signed-off-by: Michal Novotny <minovotn@redhat.com>
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---
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 block/raw-posix.c | 37 +++++++++++++++++++++++++++++++++++++
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 1 file changed, 37 insertions(+)
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diff --git a/block/raw-posix.c b/block/raw-posix.c
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index ca5bcb3..815a80b 100644
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--- a/block/raw-posix.c
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+++ b/block/raw-posix.c
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@@ -335,6 +335,22 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
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     if (S_ISREG(st.st_mode)) {
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         s->discard_zeroes = true;
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     }
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+    if (S_ISBLK(st.st_mode)) {
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+#ifdef BLKDISCARDZEROES
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+        unsigned int arg;
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+        if (ioctl(s->fd, BLKDISCARDZEROES, &arg) == 0 && arg) {
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+            s->discard_zeroes = true;
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+        }
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+#endif
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+#ifdef __linux__
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+        /* On Linux 3.10, BLKDISCARD leaves stale data in the page cache.  Do
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+         * not rely on the contents of discarded blocks unless using O_DIRECT.
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+         */
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+        if (!(bs->open_flags & BDRV_O_NOCACHE)) {
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+            s->discard_zeroes = false;
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+        }
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+#endif
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+    }
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 #ifdef CONFIG_XFS
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     if (platform_test_xfs_fd(s->fd)) {
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@@ -1586,6 +1602,26 @@ static coroutine_fn BlockDriverAIOCB *hdev_aio_discard(BlockDriverState *bs,
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                        cb, opaque, QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);
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 }
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+static coroutine_fn int hdev_co_write_zeroes(BlockDriverState *bs,
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+    int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
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+{
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+    BDRVRawState *s = bs->opaque;
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+    int rc;
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+
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+    rc = fd_open(bs);
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+    if (rc < 0) {
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+        return rc;
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+    }
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+    if (!(flags & BDRV_REQ_MAY_UNMAP)) {
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+        return -ENOTSUP;
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+    }
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+    if (!s->discard_zeroes) {
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+        return -ENOTSUP;
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+    }
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+    return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,
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+                          QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);
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+}
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+
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 static int hdev_create(const char *filename, QEMUOptionParameter *options,
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                        Error **errp)
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 {
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@@ -1637,6 +1673,7 @@ static BlockDriver bdrv_host_device = {
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     .bdrv_reopen_abort   = raw_reopen_abort,
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     .bdrv_create        = hdev_create,
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     .create_options     = raw_create_options,
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+    .bdrv_co_write_zeroes = hdev_co_write_zeroes,
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     .bdrv_aio_readv	= raw_aio_readv,
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     .bdrv_aio_writev	= raw_aio_writev,
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-- 
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1.7.11.7
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