On 2025/4/9 23:30, Darrick J. Wong wrote:
On Wed, Apr 09, 2025 at 01:29:24AM +0800, Gou Hao wrote:
After the first 'for' loop, the first call to
ifs_block_is_uptodate always evaluates to 0.
Signed-off-by: Gou Hao <gouhao@xxxxxxxxxxxxx>
---
fs/iomap/buffered-io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 31553372b33a..2f52e8e61240 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -259,7 +259,7 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
}
/* truncate len if we find any trailing uptodate block(s) */
- for ( ; i <= last; i++) {
+ for (i++; i <= last; i++) {
Hmmm... prior to the loop, $i is either the first !uptodate block, or
it's past $last. Assuming there's no overflow (there's no combination
of huge folios and tiny blksize that I can think of) then yeah, there's
no point in retesting that the same block $i is uptodate since we hold
the folio lock so nobody else could have set uptodate.
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
Thank you for your review. The explanation is very clear. I will revise the
commit message and send the V2 patch.
--
thanks,
Gou Hao
if (ifs_block_is_uptodate(ifs, i)) {
plen -= (last - i + 1) * block_size;
last = i - 1;
--
2.20.1
