loop: allow loop_set_status to re-enable direct I/O

Unlike all other calls of (__)loop_update_dio, loop_set_status never
looks at the O_DIRECT flag of the backing file, and thus doesn't
re-enable direct I/O on an O_DIRECT backing file if e.g. the new block
size would allow it.  Fix that and remove the need for the separate
__loop_update_dio flag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250110073750.1582447-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 6eb6d901151c191831aed19afe12bdc757f06400..2e1f8aa045a903adb35c479626793d9d911300b4 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -196,8 +196,9 @@ static bool lo_can_use_dio(struct loop_device *lo)
        return true;
 }
 
-static void __loop_update_dio(struct loop_device *lo, bool dio)
+static inline void loop_update_dio(struct loop_device *lo)
 {
+       bool dio = lo->use_dio || (lo->lo_backing_file->f_flags & O_DIRECT);
        bool use_dio = dio && lo_can_use_dio(lo);
 
        if (lo->use_dio == use_dio)
@@ -531,12 +532,6 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
        }
 }
 
-static inline void loop_update_dio(struct loop_device *lo)
-{
-       __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
-                               lo->use_dio);
-}
-
 static void loop_reread_partitions(struct loop_device *lo)
 {
        int rc;
@@ -1301,7 +1296,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
        }
 
        /* update the direct I/O flag if lo_offset changed */
-       __loop_update_dio(lo, lo->use_dio);
+       loop_update_dio(lo);
 
 out_unfreeze:
        blk_mq_unfreeze_queue(lo->lo_queue);