[ros-diffs] [reactos] 01/01: [NTOSKRNL] When growing a file, invalid the last VACB so that it can be refreshed

[Pierre Schweitzer]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=0917c64812c6ed182c8f7…

commit 0917c64812c6ed182c8f771309dfc628127eee2d
Author:     Pierre Schweitzer <pierre(a)reactos.org>
AuthorDate: Sun Dec 23 11:08:01 2018 +0100
Commit:     Pierre Schweitzer <pierre(a)reactos.org>
CommitDate: Sun Dec 23 11:19:14 2018 +0100

    [NTOSKRNL] When growing a file, invalid the last VACB so that it can be refreshed
    
    This will avoid corruption when a file size is little grown and read afterwards.
    Up to now, FSD where reading 0es instead of expected data, causing corruption.
    
    This fixes MS FastFAT not being able to mount a FAT volume in ReactOS, corrupting
    the FAT.
    This also fixes the CcSetFileSizes kmtest tests.
    
    This is based on a patch by Thomas Faber.
    
    CORE-11819
---
 ntoskrnl/cc/fs.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/ntoskrnl/cc/fs.c b/ntoskrnl/cc/fs.c
index e31a17b87b..5798f56a91 100644
--- a/ntoskrnl/cc/fs.c
+++ b/ntoskrnl/cc/fs.c
@@ -301,6 +301,43 @@ CcSetFileSizes (
                             0,
                             FALSE);
     }
+    else
+    {
+        PROS_VACB LastVacb;
+
+        /*
+         * If file (allocation) size has increased, then we need to check whether
+         * it just grows in a single VACB (the last one).
+         * If so, we must mark the VACB as invalid to trigger a read to the
+         * FSD at the next VACB usage, and thus avoid returning garbage
+         */
+
+        /* Check for allocation size and the last VACB */
+        if (SharedCacheMap->SectionSize.QuadPart <
FileSizes->AllocationSize.QuadPart &&
+            SharedCacheMap->SectionSize.QuadPart % VACB_MAPPING_GRANULARITY)
+        {
+            LastVacb = CcRosLookupVacb(SharedCacheMap,
+                                       SharedCacheMap->SectionSize.QuadPart);
+            if (LastVacb != NULL)
+            {
+                /* Mark it as invalid */
+                CcRosReleaseVacb(SharedCacheMap, LastVacb, LastVacb->Dirty ?
LastVacb->Valid : FALSE, FALSE, FALSE);
+            }
+        }
+
+        /* Check for file size and the last VACB */
+        if (SharedCacheMap->FileSize.QuadPart < FileSizes->FileSize.QuadPart
&&
+            SharedCacheMap->FileSize.QuadPart % VACB_MAPPING_GRANULARITY)
+        {
+            LastVacb = CcRosLookupVacb(SharedCacheMap,
+                                       SharedCacheMap->FileSize.QuadPart);
+            if (LastVacb != NULL)
+            {
+                /* Mark it as invalid */
+                CcRosReleaseVacb(SharedCacheMap, LastVacb, LastVacb->Dirty ?
LastVacb->Valid : FALSE, FALSE, FALSE);
+            }
+        }
+    }
 
     KeAcquireSpinLock(&SharedCacheMap->CacheMapLock, &oldirql);
     SharedCacheMap->SectionSize = FileSizes->AllocationSize;