fix #965: disk_io_counters() may miscalculate sector size and report …

…the wrong number of bytes read and written

HISTORY.rst

@@ -9,6 +9,8 @@
 
 - 964_: [Windows] Process.username() and psutil.users() may return badly
   decoding character on Python 3.
+- 965_: [Linux] disk_io_counters() may miscalculate sector size and report the
+  wrong number of bytes read and written.
 
 5.1.0
 =====

psutil/_pslinux.py

@@ -243,9 +243,9 @@ def file_flags_to_mode(flags):
     return mode
 
 
-def get_sector_size():
+def get_sector_size(partition):
     try:
-        with open(b"/sys/block/sda/queue/hw_sector_size") as f:
+        with open(b"/sys/block/%s/queue/hw_sector_size" % partition) as f:
             return int(f.read())
     except (IOError, ValueError):
         # man iostat states that sectors are equivalent with blocks and
@@ -254,9 +254,6 @@ def get_sector_size():
         return 512
 
 
-SECTOR_SIZE = get_sector_size()
-
-
 @memoize
 def set_scputimes_ntuple(procfs_path):
     """Return a namedtuple of variable fields depending on the
@@ -1027,8 +1024,9 @@ def get_partitions():
             raise ValueError("not sure how to interpret line %r" % line)
 
         if name in partitions:
-            rbytes = rbytes * SECTOR_SIZE
-            wbytes = wbytes * SECTOR_SIZE
+            sector_size = get_sector_size(name)
+            rbytes = rbytes * sector_size
+            wbytes = wbytes * sector_size
             retdict[name] = (reads, writes, rbytes, wbytes, rtime, wtime,
                              reads_merged, writes_merged, busy_time)
     return retdict