+ mm-fadvise-move-endbyte-calculations-to-helper-function.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm: fadvise: move 'endbyte' calculations to helper function
has been added to the -mm mm-unstable branch.  Its filename is
     mm-fadvise-move-endbyte-calculations-to-helper-function.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fadvise-move-endbyte-calculations-to-helper-function.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Charan Teja Kalla <quic_charante@quicinc.com>
Subject: mm: fadvise: move 'endbyte' calculations to helper function
Date: Tue, 14 Feb 2023 18:21:49 +0530

Patch series "mm: shmem: support POSIX_FADV_[WILL|DONT]NEED for shmem
files", v7.

This patchset aims to implement POSIX_FADV_WILLNEED and
POSIX_FADV_DONTNEED advices to shmem files which can be helpful for the
drivers who may want to manage the pages of shmem files on their own,
like, that are created through shmem_file_setup[_with_mnt]().


This patch (of 2):

Move the 'endbyte' calculations that determines last byte that fadvise can
to a helper function.  This is a preparatory change made for
shmem_fadvise() functionality in the next patch.  No functional changes in
this patch.

Link: https://lkml.kernel.org/r/cover.1676378702.git.quic_charante@quicinc.com
Link: https://lkml.kernel.org/r/22de7e716051abbafc01fab9f479f4d5b03745ca.1676378702.git.quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mark Hemment <markhemm@googlemail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/fadvise.c  |   11 +----------
 mm/internal.h |   21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 10 deletions(-)

--- a/mm/fadvise.c~mm-fadvise-move-endbyte-calculations-to-helper-function
+++ a/mm/fadvise.c
@@ -65,16 +65,7 @@ int generic_fadvise(struct file *file, l
 		return 0;
 	}
 
-	/*
-	 * Careful about overflows. Len == 0 means "as much as possible".  Use
-	 * unsigned math because signed overflows are undefined and UBSan
-	 * complains.
-	 */
-	endbyte = (u64)offset + (u64)len;
-	if (!len || endbyte < len)
-		endbyte = LLONG_MAX;
-	else
-		endbyte--;		/* inclusive */
+	endbyte = fadvise_calc_endbyte(offset, len);
 
 	switch (advice) {
 	case POSIX_FADV_NORMAL:
--- a/mm/internal.h~mm-fadvise-move-endbyte-calculations-to-helper-function
+++ a/mm/internal.h
@@ -657,6 +657,27 @@ static inline void vunmap_range_noflush(
 }
 #endif /* !CONFIG_MMU */
 
+/*
+ * Helper function to get the endbyte of a file that fadvise can operate on.
+ */
+static inline loff_t fadvise_calc_endbyte(loff_t offset, loff_t len)
+{
+	loff_t endbyte;
+
+	/*
+	 * Careful about overflows. Len == 0 means "as much as possible".  Use
+	 * unsigned math because signed overflows are undefined and UBSan
+	 * complains.
+	 */
+	endbyte = (u64)offset + (u64)len;
+	if (!len || endbyte < len)
+		endbyte = LLONG_MAX;
+	else
+		endbyte--;		/* inclusive */
+
+	return endbyte;
+}
+
 /* Memory initialisation debug and verification */
 enum mminit_level {
 	MMINIT_WARNING,
_

Patches currently in -mm which might be from quic_charante@quicinc.com are

mm-fadvise-move-endbyte-calculations-to-helper-function.patch
mm-shmem-implement-posix_fadv_need-for-shmem.patch