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 Kalla <quic_charante@xxxxxxxxxxx>
---
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 fb7c5f4..1b3cac5 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 = LLONG_MAX;
- 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 7920a8b..8d96811 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -657,6 +657,27 @@ 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 = LLONG_MAX;
+ else
+ endbyte--; /* inclusive */
+
+ return endbyte;
+}
+
/* Memory initialisation debug and verification */
enum mminit_level {
MMINIT_WARNING,
--
2.7.4
