From adf32529b8b95ed360356f13bd9a7f2a4b707412 Mon Sep 17 00:00:00 2001

Message-Id: <adf32529b8b95ed360356f13bd9a7f2a4b707412.1389014116.git.minovotn@redhat.com>

In-Reply-To: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>

References: <c8cc35838d42aa286242772d97e3a9be7bb786ba.1389014116.git.minovotn@redhat.com>

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Mon, 9 Dec 2013 14:09:29 +0100

Subject: [PATCH 41/50] raw-posix: add support for write_zeroes on XFS and

 block devices

RH-Author: Paolo Bonzini <pbonzini@redhat.com>

Message-id: <1386598178-11845-44-git-send-email-pbonzini@redhat.com>

Patchwork-id: 56080

O-Subject: [RHEL 7.0 qemu-kvm PATCH 43/52] raw-posix: add support for write_zeroes on XFS and block devices

Bugzilla: 1007815

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

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

The code is similar to the implementation of discard and write_zeroes

with UNMAP.  However, failure must be propagated up to block.c.

The stale page cache problem can be reproduced as follows:

    # modprobe scsi-debug lbpws=1 lbprz=1

    # ./qemu-io /dev/sdXX

    qemu-io> write -P 0xcc 0 2M

    qemu-io> write -z 0 1M

    qemu-io> read -P 0x00 0 512

    Pattern verification failed at offset 0, 512 bytes

    qemu-io> read -v 0 512

    00000000:  cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc  ................

    ...

    # ./qemu-io --cache=none /dev/sdXX

    qemu-io> write -P 0xcc 0 2M

    qemu-io> write -z 0 1M

    qemu-io> read -P 0x00 0 512

    qemu-io> read -v 0 512

    00000000:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................

    ...

And similarly with discard instead of "write -z".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit 97a2ae34537882df34810d538ab1f51085499d2c)

---

 block/raw-aio.h   |  3 +-

 block/raw-posix.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++--------

 2 files changed, 74 insertions(+), 13 deletions(-)

Signed-off-by: Michal Novotny <minovotn@redhat.com>

---

 block/raw-aio.h   |  3 +-

 block/raw-posix.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++--------

 2 files changed, 74 insertions(+), 13 deletions(-)

diff --git a/block/raw-aio.h b/block/raw-aio.h

index c61f159..7ad0a8a 100644

--- a/block/raw-aio.h

+++ b/block/raw-aio.h

@@ -21,9 +21,10 @@

 #define QEMU_AIO_IOCTL        0x0004

 #define QEMU_AIO_FLUSH        0x0008

 #define QEMU_AIO_DISCARD      0x0010

+#define QEMU_AIO_WRITE_ZEROES 0x0020

 #define QEMU_AIO_TYPE_MASK \

         (QEMU_AIO_READ|QEMU_AIO_WRITE|QEMU_AIO_IOCTL|QEMU_AIO_FLUSH| \

-         QEMU_AIO_DISCARD)

+         QEMU_AIO_DISCARD|QEMU_AIO_WRITE_ZEROES)

 /* AIO flags */

 #define QEMU_AIO_MISALIGNED   0x1000

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

index 815a80b..f410668 100644

--- a/block/raw-posix.c

+++ b/block/raw-posix.c

@@ -142,6 +142,7 @@ typedef struct BDRVRawState {

     bool is_xfs:1;

 #endif

     bool has_discard:1;

+    bool has_write_zeroes:1;

     bool discard_zeroes:1;

 } BDRVRawState;

@@ -327,6 +328,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,

 #endif

     s->has_discard = true;

+    s->has_write_zeroes = true;

     if (fstat(s->fd, &st) < 0) {

         error_setg_errno(errp, errno, "Could not stat file");

@@ -345,9 +347,11 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,

 #ifdef __linux__

         /* On Linux 3.10, BLKDISCARD leaves stale data in the page cache.  Do

          * not rely on the contents of discarded blocks unless using O_DIRECT.

+         * Same for BLKZEROOUT.

          */

         if (!(bs->open_flags & BDRV_O_NOCACHE)) {

             s->discard_zeroes = false;

+            s->has_write_zeroes = false;

         }

 #endif

     }

@@ -703,6 +707,23 @@ static ssize_t handle_aiocb_rw(RawPosixAIOData *aiocb)

 }

 #ifdef CONFIG_XFS

+static int xfs_write_zeroes(BDRVRawState *s, int64_t offset, uint64_t bytes)

+{

+    struct xfs_flock64 fl;

+

+    memset(&fl, 0, sizeof(fl));

+    fl.l_whence = SEEK_SET;

+    fl.l_start = offset;

+    fl.l_len = bytes;

+

+    if (xfsctl(NULL, s->fd, XFS_IOC_ZERO_RANGE, &fl) < 0) {

+        DEBUG_BLOCK_PRINT("cannot write zero range (%s)\n", strerror(errno));

+        return -errno;

+    }

+

+    return 0;

+}

+

 static int xfs_discard(BDRVRawState *s, int64_t offset, uint64_t bytes)

 {

     struct xfs_flock64 fl;

@@ -721,6 +742,42 @@ static int xfs_discard(BDRVRawState *s, int64_t offset, uint64_t bytes)

 }

 #endif

+static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb)

+{

+    int ret = -EOPNOTSUPP;

+    BDRVRawState *s = aiocb->bs->opaque;

+

+    if (s->has_write_zeroes == 0) {

+        return -ENOTSUP;

+    }

+

+    if (aiocb->aio_type & QEMU_AIO_BLKDEV) {

+#ifdef BLKZEROOUT

+        do {

+            uint64_t range[2] = { aiocb->aio_offset, aiocb->aio_nbytes };

+            if (ioctl(aiocb->aio_fildes, BLKZEROOUT, range) == 0) {

+                return 0;

+            }

+        } while (errno == EINTR);

+

+        ret = -errno;

+#endif

+    } else {

+#ifdef CONFIG_XFS

+        if (s->is_xfs) {

+            return xfs_write_zeroes(s, aiocb->aio_offset, aiocb->aio_nbytes);

+        }

+#endif

+    }

+

+    if (ret == -ENODEV || ret == -ENOSYS || ret == -EOPNOTSUPP ||

+        ret == -ENOTTY) {

+        s->has_write_zeroes = false;

+        ret = -ENOTSUP;

+    }

+    return ret;

+}

+

 static ssize_t handle_aiocb_discard(RawPosixAIOData *aiocb)

 {

     int ret = -EOPNOTSUPP;

@@ -805,6 +862,9 @@ static int aio_worker(void *arg)

     case QEMU_AIO_DISCARD:

         ret = handle_aiocb_discard(aiocb);

         break;

+    case QEMU_AIO_WRITE_ZEROES:

+        ret = handle_aiocb_write_zeroes(aiocb);

+        break;

     default:

         fprintf(stderr, "invalid aio request (0x%x)\n", aiocb->aio_type);

         ret = -EINVAL;

@@ -1257,13 +1317,13 @@ static int coroutine_fn raw_co_write_zeroes(

     BDRVRawState *s = bs->opaque;

     if (!(flags & BDRV_REQ_MAY_UNMAP)) {

-        return -ENOTSUP;

-    }

-    if (!s->discard_zeroes) {

-        return -ENOTSUP;

+        return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,

+                              QEMU_AIO_WRITE_ZEROES);

+    } else if (s->discard_zeroes) {

+        return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,

+                              QEMU_AIO_DISCARD);

     }

-    return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,

-                          QEMU_AIO_DISCARD);

+    return -ENOTSUP;

 }

 static int raw_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)

@@ -1613,13 +1673,13 @@ static coroutine_fn int hdev_co_write_zeroes(BlockDriverState *bs,

         return rc;

     }

     if (!(flags & BDRV_REQ_MAY_UNMAP)) {

-        return -ENOTSUP;

-    }

-    if (!s->discard_zeroes) {

-        return -ENOTSUP;

+        return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,

+                              QEMU_AIO_WRITE_ZEROES|QEMU_AIO_BLKDEV);

+    } else if (s->discard_zeroes) {

+        return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,

+                              QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);

     }

-    return paio_submit_co(bs, s->fd, sector_num, NULL, nb_sectors,

-                          QEMU_AIO_DISCARD|QEMU_AIO_BLKDEV);

+    return -ENOTSUP;

 }

 static int hdev_create(const char *filename, QEMUOptionParameter *options,

-- 

1.7.11.7