LU-11157 obd: keep dirty_max_pages a round number of MB

In client_adjust_max_dirty() ensure that the dirty pages limit is
always divisible by 256 so that it may faithfully be represented in MB
as is the case when the max_dirty_mb parameters are used.

Test-Parameters: trivial

Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: I8e2fbdd4bf253a46e2951e7840484ab6a617fbe2
Reviewed-on: https://review.whamcloud.com/32831
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>

diff --git a/lustre/include/obd.h b/lustre/include/obd.h
index 14aa618..6f02b59 100644 (file)
--- a/lustre/include/obd.h
+++ b/lustre/include/obd.h
@@ -1223,7 +1223,8 @@ static inline int cli_brw_size(struct obd_device *obd)
        return obd->u.cli.cl_max_pages_per_rpc << PAGE_SHIFT;
 }
 
-/* when RPC size or the max RPCs in flight is increased, the max dirty pages
+/*
+ * When RPC size or the max RPCs in flight is increased, the max dirty pages
  * of the client should be increased accordingly to avoid sending fragmented
  * RPCs over the network when the client runs out of the maximum dirty space
  * when so many RPCs are being generated.
@@ -1231,10 +1232,10 @@ static inline int cli_brw_size(struct obd_device *obd)
 static inline void client_adjust_max_dirty(struct client_obd *cli)
 {
         /* initializing */
-       if (cli->cl_dirty_max_pages <= 0)
-               cli->cl_dirty_max_pages = (OSC_MAX_DIRTY_DEFAULT * 1024 * 1024)
-                                                       >> PAGE_SHIFT;
-       else {
+       if (cli->cl_dirty_max_pages <= 0) {
+               cli->cl_dirty_max_pages =
+                       (OSC_MAX_DIRTY_DEFAULT * 1024 * 1024) >> PAGE_SHIFT;
+       } else {
                unsigned long dirty_max = cli->cl_max_rpcs_in_flight *
                                          cli->cl_max_pages_per_rpc;
 
@@ -1244,6 +1245,12 @@ static inline void client_adjust_max_dirty(struct client_obd *cli)
 
        if (cli->cl_dirty_max_pages > totalram_pages / 8)
                cli->cl_dirty_max_pages = totalram_pages / 8;
+
+       /* This value is exported to userspace through the max_dirty_mb
+        * parameter.  So we round up the number of pages to make it a round
+        * number of MBs. */
+       cli->cl_dirty_max_pages = round_up(cli->cl_dirty_max_pages,
+                                          1 << (20 - PAGE_SHIFT));
 }
 
 #endif /* __OBD_H */