Hi shenmeng,

On Wed, Aug 07, 2019 at 10:36:55PM +0800, [email protected] wrote:
> From: shenmeng996 <[email protected]>
> 
> fstat return block device's size of zero.
> use ioctl to get block device's size.
> 
> Signed-off-by: shenmeng996 <[email protected]>


Thanks for your patch v2 :)

It looks good to me, and I update this patch so that
autoconf can check these new header files.
https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git/commit/?h=experimental&id=0f225449962b4a9716985e7530a395a9500d0de6
Do you agree with this modification? please share your thought about this.

Thanks,
Gao Xiang

diff --git a/configure.ac b/configure.ac
index 6f4eacc..fcdf30a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -73,12 +73,14 @@ AC_CHECK_HEADERS(m4_flatten([
        fcntl.h
        inttypes.h
        linux/falloc.h
+       linux/fs.h
        linux/types.h
        limits.h
        stddef.h
        stdint.h
        stdlib.h
        string.h
+       sys/ioctl.h
        sys/stat.h
        sys/time.h
        unistd.h
diff --git a/lib/io.c b/lib/io.c
index 93328d3..15c5a35 100644
--- a/lib/io.c
+++ b/lib/io.c
@@ -9,7 +9,11 @@
 #define _LARGEFILE64_SOURCE
 #define _GNU_SOURCE
 #include <sys/stat.h>
+#include <sys/ioctl.h>
 #include "erofs/io.h"
+#ifdef HAVE_LINUX_FS_H
+#include <linux/fs.h>
+#endif
 #ifdef HAVE_LINUX_FALLOC_H
 #include <linux/falloc.h>
 #endif
@@ -21,6 +25,26 @@ static const char *erofs_devname;
 static int erofs_devfd = -1;
 static u64 erofs_devsz;
 
+int dev_get_blkdev_size(int fd, u64 *bytes)
+{
+       errno = ENOTSUP;
+#ifdef BLKGETSIZE64
+       if (ioctl(fd, BLKGETSIZE64, bytes) >= 0)
+               return 0;
+#endif
+
+#ifdef BLKGETSIZE
+       {
+               unsigned long size;
+               if (ioctl(fd, BLKGETSIZE, &size) >= 0) {
+                       *bytes = ((u64)size << 9);
+                       return 0;
+               }
+       }
+#endif
+       return -errno;
+}
+
 void dev_close(void)
 {
        close(erofs_devfd);
@@ -49,7 +73,12 @@ int dev_open(const char *dev)
 
        switch (st.st_mode & S_IFMT) {
        case S_IFBLK:
-               erofs_devsz = st.st_size;
+               ret = dev_get_blkdev_size(fd, &erofs_devsz);
+               if (ret) {
+                       erofs_err("failed to get block device size(%s).", dev);
+                       close(fd);
+                       return ret;
+               }
                break;
        case S_IFREG:
                ret = ftruncate(fd, 0);
-- 
2.17.1

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