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authoraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>2009-04-07 18:43:24 +0000
committeraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>2009-04-07 18:43:24 +0000
commitf141eafe286c785f7e2c1e312a73f90d66bdfb90 (patch)
tree049474e891e06deec79bd3d58d49b49ba627276a /posix-aio-compat.c
parentremove bdrv_aio_read/bdrv_aio_write (Christoph Hellwig) (diff)
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push down vector linearization to posix-aio-compat.c (Christoph Hellwig)
Make all AIO requests vectored and defer linearization until the actual I/O thread. This prepares for using native preadv/pwritev. Also enables asynchronous direct I/O by handling that case in the I/O thread. Qcow and qcow2 propably want to be adopted to directly deal with multi-segment requests, but that can be implemented later. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7020 c046a42c-6fe2-441c-8c8c-71466251a162
Diffstat (limited to 'posix-aio-compat.c')
-rw-r--r--posix-aio-compat.c118
1 files changed, 92 insertions, 26 deletions
diff --git a/posix-aio-compat.c b/posix-aio-compat.c
index 65c80ecc3..0eb77a50d 100644
--- a/posix-aio-compat.c
+++ b/posix-aio-compat.c
@@ -20,6 +20,7 @@
#include <stdlib.h>
#include <stdio.h>
#include "osdep.h"
+#include "qemu-common.h"
#include "posix-aio-compat.h"
@@ -76,45 +77,110 @@ static void thread_create(pthread_t *thread, pthread_attr_t *attr,
if (ret) die2(ret, "pthread_create");
}
-static size_t handle_aiocb_readwrite(struct qemu_paiocb *aiocb)
+static size_t handle_aiocb_ioctl(struct qemu_paiocb *aiocb)
+{
+ int ret;
+
+ ret = ioctl(aiocb->aio_fildes, aiocb->aio_ioctl_cmd, aiocb->aio_ioctl_buf);
+ if (ret == -1)
+ return -errno;
+ return ret;
+}
+
+/*
+ * Check if we need to copy the data in the aiocb into a new
+ * properly aligned buffer.
+ */
+static int aiocb_needs_copy(struct qemu_paiocb *aiocb)
+{
+ if (aiocb->aio_flags & QEMU_AIO_SECTOR_ALIGNED) {
+ int i;
+
+ for (i = 0; i < aiocb->aio_niov; i++)
+ if ((uintptr_t) aiocb->aio_iov[i].iov_base % 512)
+ return 1;
+ }
+
+ return 0;
+}
+
+static size_t handle_aiocb_rw_linear(struct qemu_paiocb *aiocb, char *buf)
{
size_t offset = 0;
- ssize_t len;
+ size_t len;
while (offset < aiocb->aio_nbytes) {
- if (aiocb->aio_type == QEMU_PAIO_WRITE)
- len = pwrite(aiocb->aio_fildes,
- (const char *)aiocb->aio_buf + offset,
+ if (aiocb->aio_type == QEMU_PAIO_WRITE)
+ len = pwrite(aiocb->aio_fildes,
+ (const char *)buf + offset,
+ aiocb->aio_nbytes - offset,
+ aiocb->aio_offset + offset);
+ else
+ len = pread(aiocb->aio_fildes,
+ buf + offset,
aiocb->aio_nbytes - offset,
aiocb->aio_offset + offset);
- else
- len = pread(aiocb->aio_fildes,
- (char *)aiocb->aio_buf + offset,
- aiocb->aio_nbytes - offset,
- aiocb->aio_offset + offset);
-
- if (len == -1 && errno == EINTR)
- continue;
- else if (len == -1) {
- offset = -errno;
- break;
- } else if (len == 0)
- break;
- offset += len;
+ if (len == -1 && errno == EINTR)
+ continue;
+ else if (len == -1) {
+ offset = -errno;
+ break;
+ } else if (len == 0)
+ break;
+
+ offset += len;
}
return offset;
}
-static size_t handle_aiocb_ioctl(struct qemu_paiocb *aiocb)
+static size_t handle_aiocb_rw(struct qemu_paiocb *aiocb)
{
- int ret;
+ size_t nbytes;
+ char *buf;
+
+ if (!aiocb_needs_copy(aiocb) && aiocb->aio_niov == 1) {
+ /*
+ * If there is just a single buffer, and it is properly aligned
+ * we can just use plain pread/pwrite without any problems.
+ */
+ return handle_aiocb_rw_linear(aiocb, aiocb->aio_iov->iov_base);
+ }
- ret = ioctl(aiocb->aio_fildes, aiocb->aio_ioctl_cmd, aiocb->aio_buf);
- if (ret == -1)
- return -errno;
- return ret;
+ /*
+ * Ok, we have to do it the hard way, copy all segments into
+ * a single aligned buffer.
+ */
+ buf = qemu_memalign(512, aiocb->aio_nbytes);
+ if (aiocb->aio_type == QEMU_PAIO_WRITE) {
+ char *p = buf;
+ int i;
+
+ for (i = 0; i < aiocb->aio_niov; ++i) {
+ memcpy(p, aiocb->aio_iov[i].iov_base, aiocb->aio_iov[i].iov_len);
+ p += aiocb->aio_iov[i].iov_len;
+ }
+ }
+
+ nbytes = handle_aiocb_rw_linear(aiocb, buf);
+ if (aiocb->aio_type != QEMU_PAIO_WRITE) {
+ char *p = buf;
+ size_t count = aiocb->aio_nbytes, copy;
+ int i;
+
+ for (i = 0; i < aiocb->aio_niov && count; ++i) {
+ copy = count;
+ if (copy > aiocb->aio_iov[i].iov_len)
+ copy = aiocb->aio_iov[i].iov_len;
+ memcpy(aiocb->aio_iov[i].iov_base, p, copy);
+ p += copy;
+ count -= copy;
+ }
+ }
+ qemu_vfree(buf);
+
+ return nbytes;
}
static void *aio_thread(void *unused)
@@ -157,7 +223,7 @@ static void *aio_thread(void *unused)
switch (aiocb->aio_type) {
case QEMU_PAIO_READ:
case QEMU_PAIO_WRITE:
- ret = handle_aiocb_readwrite(aiocb);
+ ret = handle_aiocb_rw(aiocb);
break;
case QEMU_PAIO_IOCTL:
ret = handle_aiocb_ioctl(aiocb);