The current boundary check for nr_to_read in do_page_cache_ra can lead
to a redundant self-assignment when the desired read length precisely
matches the remaining pages to the end of the file.
Currently, the code is:
if (nr_to_read > end_index - index)
nr_to_read = end_index - index + 1;
If nr_to_read is, for instance, 3, and end_index - index + 1 is also 3
(meaning 3 pages remain), the condition 3 > 2 evaluates to true, leading
to nr_to_read being assigned 3 again. While compilers might optimize
this trivial self-assignment, it introduces unnecessary logical overhead
and reduces code clarity.
This patch refines the condition to be more explicit and avoid this
redundant assignment:
if (nr_to_read > end_index - index + 1)
nr_to_read = end_index - index + 1;
This ensures the assignment only occurs when nr_to_read genuinely
exceeds the available pages, improving code precision and slightly
enhancing readability without altering the core functionality.
Signed-off-by: Xiaole He <hexiaole1994@xxxxxxx>
---
mm/readahead.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/readahead.c b/mm/readahead.c
index 20d36d6b055e..bbcfbebe7569 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -321,7 +321,7 @@ static void do_page_cache_ra(struct readahead_control *ractl,
if (index > end_index)
return;
/* Don't read past the page containing the last byte of the file */
- if (nr_to_read > end_index - index)
+ if (nr_to_read > end_index - index + 1)
nr_to_read = end_index - index + 1;
page_cache_ra_unbounded(ractl, nr_to_read, lookahead_size);
--
2.43.0
