Re: [PATCH v6 07/33] util: introduce qemu_file_get_page_size()

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On 11/09/2015 06:33 PM, Michael S. Tsirkin wrote:
On Fri, Oct 30, 2015 at 01:56:01PM +0800, Xiao Guangrong wrote:
There are three places use the some logic to get the page size on
the file path or file fd

This patch introduces qemu_file_get_page_size() to unify the code

Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
---
  include/qemu/osdep.h |  1 +
  target-ppc/kvm.c     | 21 +++------------------
  util/oslib-posix.c   | 16 ++++++++++++++++
  util/oslib-win32.c   |  5 +++++
  4 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index b568424..d4dde02 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -302,4 +302,5 @@ int qemu_read_password(char *buf, int buf_size);
   */
  pid_t qemu_fork(Error **errp);

+size_t qemu_file_get_page_size(const char *mem_path);
  #endif
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index ac70f08..c661f1c 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -308,28 +308,13 @@ static void kvm_get_smmu_info(PowerPCCPU *cpu, struct kvm_ppc_smmu_info *info)

  static long gethugepagesize(const char *mem_path)
  {
-    struct statfs fs;
-    int ret;
-
-    do {
-        ret = statfs(mem_path, &fs);
-    } while (ret != 0 && errno == EINTR);
+    long size = qemu_file_get_page_size(mem_path);

-    if (ret != 0) {
-        fprintf(stderr, "Couldn't statfs() memory path: %s\n",
-                strerror(errno));
+    if (!size) {
          exit(1);
      }

-#define HUGETLBFS_MAGIC       0x958458f6
-
-    if (fs.f_type != HUGETLBFS_MAGIC) {
-        /* Explicit mempath, but it's ordinary pages */
-        return getpagesize();
-    }
-
-    /* It's hugepage, return the huge page size */
-    return fs.f_bsize;
+    return size;
  }

  static int find_max_supported_pagesize(Object *obj, void *opaque)
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 914cef5..ad94c5a 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -360,6 +360,22 @@ static size_t fd_getpagesize(int fd)
      return getpagesize();
  }

+size_t qemu_file_get_page_size(const char *path)
+{
+    size_t size = 0;
+    int fd = qemu_open(path, O_RDONLY);
+
+    if (fd < 0) {
+        fprintf(stderr, "Could not open %s.\n", path);
+        goto exit;
+    }
+
+    size = fd_getpagesize(fd);
+    qemu_close(fd);
+exit:
+    return size;
+}
+
  void os_mem_prealloc(int fd, char *area, size_t memory)
  {
      int ret;

So this is opening the file for the sole purpose of
doing the fstatfs on it. Seems strange, just do statfs instead.
In fact, maybe we want statfs_getpagesize.

It is just to reuse the code of fd_getpagesize() which already has
the logic to check pagesize.


diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index 09f9e98..a18aa87 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -462,6 +462,11 @@ size_t getpagesize(void)
      return system_info.dwPageSize;
  }

+size_t qemu_file_get_page_size(const char *path)
+{
+    return getpagesize();
+}
+
  void os_mem_prealloc(int fd, char *area, size_t memory)
  {
      int i;

And why is this needed on win32?

It is not actually used, just make osdep.h happy which has
qemu_file_get_page_size() declare.

BTW, i will drop this patch for now on.

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