dm: remove useless test in alloc_multiple_bios

Commit Message

Mikulas Patocka Jan. 9, 2025, 1:47 p.m. UTC

The test gfp_flag & GFP_NOWAIT was always true, because both GFP_NOIO and
GFP_NOWAIT include the flag __GFP_KSWAPD_RECLAIM. Luckily, this oversight
didn't result in any harm; the loop always started with "try = 0".

This patch removes the faulty test and explicitly starts the loop with
"try = 0" (so that we don't hold the mutex in the first iteration).

Signed-off-by: Mikulas Patocka <[e-mail]>

---
 drivers/md/dm.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

Patch

Index: linux-2.6/drivers/md/dm.c
===================================================================
--- linux-2.6.orig/drivers/md/dm.c	2025-01-08 17:24:52.000000000 +0100
+++ linux-2.6/drivers/md/dm.c	2025-01-08 17:26:52.000000000 +0100
@@ -1479,12 +1479,12 @@  static void setup_split_accounting(struc
 
 static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
 				struct dm_target *ti, unsigned int num_bios,
-				unsigned *len, gfp_t gfp_flag)
+				unsigned *len)
 {
 	struct bio *bio;
-	int try = (gfp_flag & GFP_NOWAIT) ? 0 : 1;
+	int try;
 
-	for (; try < 2; try++) {
+	for (try = 0; try < 2; try++) {
 		int bio_nr;
 
 		if (try && num_bios > 1)
@@ -1508,8 +1508,7 @@  static void alloc_multiple_bios(struct b
 }
 
 static unsigned int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
-					  unsigned int num_bios, unsigned int *len,
-					  gfp_t gfp_flag)
+					  unsigned int num_bios, unsigned int *len)
 {
 	struct bio_list blist = BIO_EMPTY_LIST;
 	struct bio *clone;
@@ -1526,7 +1525,7 @@  static unsigned int __send_duplicate_bio
 	 * Using alloc_multiple_bios(), even if num_bios is 1, to consistently
 	 * support allocating using GFP_NOWAIT with GFP_NOIO fallback.
 	 */
-	alloc_multiple_bios(&blist, ci, ti, num_bios, len, gfp_flag);
+	alloc_multiple_bios(&blist, ci, ti, num_bios, len);
 	while ((clone = bio_list_pop(&blist))) {
 		if (num_bios > 1)
 			dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO);
@@ -1564,7 +1563,7 @@  static void __send_empty_flush(struct cl
 
 			atomic_add(ti->num_flush_bios, &ci->io->io_count);
 			bios = __send_duplicate_bios(ci, ti, ti->num_flush_bios,
-						     NULL, GFP_NOWAIT);
+						     NULL);
 			atomic_sub(ti->num_flush_bios - bios, &ci->io->io_count);
 		}
 	} else {
@@ -1612,7 +1611,7 @@  static void __send_abnormal_io(struct cl
 		    __max_io_len(ti, ci->sector, max_granularity, max_sectors));
 
 	atomic_add(num_bios, &ci->io->io_count);
-	bios = __send_duplicate_bios(ci, ti, num_bios, &len, GFP_NOIO);
+	bios = __send_duplicate_bios(ci, ti, num_bios, &len);
 	/*
 	 * alloc_io() takes one extra reference for submission, so the
 	 * reference won't reach 0 without the following (+1) subtraction
@@ -1849,7 +1848,7 @@  static blk_status_t __send_zone_reset_al
 			 * not go crazy with the clone allocation.
 			 */
 			alloc_multiple_bios(&blist, ci, ti, min(nr_reset, 32),
-					    NULL, GFP_NOIO);
+					    NULL);
 		}
 
 		/* Get a clone and change it to a regular reset operation. */
@@ -1881,7 +1880,7 @@  static void __send_zone_reset_all_native
 	unsigned int bios;
 
 	atomic_add(1, &ci->io->io_count);
-	bios = __send_duplicate_bios(ci, ti, 1, NULL, GFP_NOIO);
+	bios = __send_duplicate_bios(ci, ti, 1, NULL);
 	atomic_sub(1 - bios, &ci->io->io_count);
 
 	ci->sector_count = 0;