[reactos] 01/03: [NTOS:MM] Do not chunk-read files marked with FO_RANDOM_ACCESS

[Jérôme Gardou]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=35c091adaf7ee70a57743f...

commit 35c091adaf7ee70a57743f29ab288e3ca0881366
Author:     Jérôme Gardou [e-mail]
AuthorDate: Tue Feb 16 11:27:19 2021 +0100
Commit:     Jérôme Gardou [e-mail]
CommitDate: Fri Feb 26 08:46:53 2021 +0100

[NTOS:MM] Do not chunk-read files marked with FO_RANDOM_ACCESS
---
 ntoskrnl/mm/section.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/ntoskrnl/mm/section.c b/ntoskrnl/mm/section.c
index 3f364b49f4d..ea56635b72f 100644
--- a/ntoskrnl/mm/section.c
+++ b/ntoskrnl/mm/section.c
@@ -1200,9 +1200,19 @@ MmMakeSegmentResident(
     if (!NT_SUCCESS(Status))
         return Status;

-    RangeStart = Offset - (Offset % _64K);
-    if (RangeEnd % _64K)
-        RangeEnd += _64K - (RangeEnd % _64K);
+    /* If the file is not random access, read a 64K Chunk. */
+    if (!FlagOn(FileObject->Flags, FO_RANDOM_ACCESS))
+    {
+        RangeStart = Offset - (Offset % _64K);
+        if (RangeEnd % _64K)
+            RangeEnd += _64K - (RangeEnd % _64K);
+    }
+    else
+    {
+        RangeStart = Offset  - (Offset % PAGE_SIZE);
+        if (RangeEnd % PAGE_SIZE)
+            RangeEnd += PAGE_SIZE - (RangeEnd % PAGE_SIZE);
+    }

/* Clamp if needed */
     if (!FlagOn(*Segment->Flags, MM_DATAFILE_SEGMENT))