From: Charan Teja Reddy <[email protected]>
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.
Signed-off-by: Charan Teja Reddy <[email protected]>
---
Changes in V5:
-- Moved the 'endbyte' calculation to a helper function.
-- This patch is newly raised in V5 thus no change exists from v1 to v4.
mm/fadvise.c | 11 +----------
mm/internal.h | 21 +++++++++++++++++++++
2 files changed, 22 insertions(+), 10 deletions(-)
diff --git a/mm/fadvise.c b/mm/fadvise.c
index d6baa4f..086e929 100644
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -65,16 +65,7 @@ int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
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 = -1;
- else
- endbyte--; /* inclusive */
+ endbyte = fadvise_calc_endbyte(offset, len);
switch (advice) {
case POSIX_FADV_NORMAL:
diff --git a/mm/internal.h b/mm/internal.h
index d8030039..91bb17d 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -506,6 +506,27 @@ static inline void vunmap_range_noflush(unsigned long start, unsigned long end)
#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 = -1;
+ else
+ endbyte--; /* inclusive */
+
+ return endbyte;
+}
+
+/*
* Return the mem_map entry representing the 'offset' subpage within
* the maximally aligned gigantic page 'base'. Handle any discontiguity
* in the mem_map at MAX_ORDER_NR_PAGES boundaries.
--
2.7.4