03/03: [NTOSKRNL] Modified CcCanIWrite to handle Mm throttling limits

[Pierre Schweitzer]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=5d93941d31c714579ff3b…

commit 5d93941d31c714579ff3b3bedb766c6448aeaccb
Author:     Pierre Schweitzer <pierre(a)reactos.org>
AuthorDate: Fri Feb 9 14:22:00 2018 +0100
Commit:     Pierre Schweitzer <pierre(a)reactos.org>
CommitDate: Fri Feb 9 14:22:00 2018 +0100

    [NTOSKRNL] Modified CcCanIWrite to handle Mm throttling limits
---
 ntoskrnl/cc/copy.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/ntoskrnl/cc/copy.c b/ntoskrnl/cc/copy.c
index 40897028fc..a3b1f887aa 100644
--- a/ntoskrnl/cc/copy.c
+++ b/ntoskrnl/cc/copy.c
@@ -697,10 +697,16 @@ CcCanIWrite (
     /* So, now allow write if:
      * - Not the first try or we have no throttling yet
      * AND:
-     * - We don't execeed threshold!
+     * - We don't exceed threshold!
+     * - We don't exceed what Mm can allow us to use
+     *   + If we're above top, that's fine
+     *   + If we're above bottom with limited modified pages, that's fine
+     *   + Otherwise, throttle!
      */
     if ((TryContext != FirstTry || IsListEmpty(&CcDeferredWrites)) &&
         CcTotalDirtyPages + Pages < CcDirtyPageThreshold &&
+        (MmAvailablePages > MmThrottleTop ||
+         (MmModifiedPageListHead.Total < 1000 && MmAvailablePages >
MmThrottleBottom)) &&
         !PerFileDefer)
     {
         return TRUE;