https://git.reactos.org/?p=reactos.git;a=commitdiff;h=e19e907a2c40fa90a238e78b146b5dfc3fe715a3
commit e19e907a2c40fa90a238e78b146b5dfc3fe715a3 Author: Pierre Schweitzer <[email protected]> AuthorDate: Thu Oct 4 10:42:13 2018 +0200 Commit: Pierre Schweitzer <[email protected]> CommitDate: Thu Oct 4 10:45:10 2018 +0200 [NTOSKRNL] Quickly check for alignment in NtRead/WriteFile This quick check based on bits and operation is for 2^ based sector sizes (most of the cases) and will perform faster than the modulo operation which is still used in fallback in case the sector size wouldn't be a power of 2. --- ntoskrnl/io/iomgr/iofunc.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/ntoskrnl/io/iomgr/iofunc.c b/ntoskrnl/io/iomgr/iofunc.c index 01a956505f..61fd88f8fd 100644 --- a/ntoskrnl/io/iomgr/iofunc.c +++ b/ntoskrnl/io/iomgr/iofunc.c @@ -2612,13 +2612,19 @@ NtReadFile(IN HANDLE FileHandle, /* Perform additional checks for non-cached file access */ if (FileObject->Flags & FO_NO_INTERMEDIATE_BUFFERING) { - /* Fail if Length is not sector size aligned */ + /* Fail if Length is not sector size aligned + * Perform a quick check for 2^ sector sizes + * If it fails, try a more standard way + */ if ((DeviceObject->SectorSize != 0) && - (Length % DeviceObject->SectorSize != 0)) + ((DeviceObject->SectorSize - 1) & Length) != 0) { - /* Release the file object and and fail */ - ObDereferenceObject(FileObject); - return STATUS_INVALID_PARAMETER; + if (Length % DeviceObject->SectorSize != 0) + { + /* Release the file object and and fail */ + ObDereferenceObject(FileObject); + return STATUS_INVALID_PARAMETER; + } } /* Fail if buffer doesn't match alignment requirements */ @@ -3649,13 +3655,19 @@ NtWriteFile(IN HANDLE FileHandle, /* Perform additional checks for non-cached file access */ if (FileObject->Flags & FO_NO_INTERMEDIATE_BUFFERING) { - /* Fail if Length is not sector size aligned */ + /* Fail if Length is not sector size aligned + * Perform a quick check for 2^ sector sizes + * If it fails, try a more standard way + */ if ((DeviceObject->SectorSize != 0) && - (Length % DeviceObject->SectorSize != 0)) + ((DeviceObject->SectorSize - 1) & Length) != 0) { - /* Release the file object and and fail */ - ObDereferenceObject(FileObject); - return STATUS_INVALID_PARAMETER; + if (Length % DeviceObject->SectorSize != 0) + { + /* Release the file object and and fail */ + ObDereferenceObject(FileObject); + return STATUS_INVALID_PARAMETER; + } } /* Fail if buffer doesn't match alignment requirements */
