[013/227] remove bdi_congested() and wb_congested() and related functions

Commit Message

Andrew Morton March 22, 2022, 9:39 p.m. UTC

From: NeilBrown <[e-mail]>
Subject: remove bdi_congested() and wb_congested() and related functions

These functions are no longer useful as no BDIs report congestions any
more.

Removing the test on bdi_write_contested() in current_may_throttle() could
cause a small change in behaviour, but only when PF_LOCAL_THROTTLE is set.

So replace the calls by 'false' and simplify the code - and remove the
functions.

[[e-mail]: fix build]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: NeilBrown <[e-mail]>
Acked-by: Ryusuke Konishi <[e-mail]>	[nilfs]
Cc: Anna Schumaker <[e-mail]>
Cc: Chao Yu <[e-mail]>
Cc: Darrick J. Wong <[e-mail]>
Cc: Ilya Dryomov <[e-mail]>
Cc: Jaegeuk Kim <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: Jeff Layton <[e-mail]>
Cc: Jens Axboe <[e-mail]>
Cc: Lars Ellenberg <[e-mail]>
Cc: Miklos Szeredi <[e-mail]>
Cc: Paolo Valente <[e-mail]>
Cc: Philipp Reisner <[e-mail]>
Cc: Trond Myklebust <[e-mail]>
Cc: Wu Fengguang <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 drivers/block/drbd/drbd_int.h |    3 ---
 drivers/block/drbd/drbd_req.c |    3 +--
 fs/ext2/ialloc.c              |    5 -----
 fs/nilfs2/segbuf.c            |   16 ----------------
 fs/xfs/xfs_buf.c              |    3 ---
 include/linux/backing-dev.h   |   26 --------------------------
 mm/vmscan.c                   |    4 +---
 7 files changed, 2 insertions(+), 58 deletions(-)

Patch

--- a/drivers/block/drbd/drbd_int.h~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/drivers/block/drbd/drbd_int.h
@@ -638,9 +638,6 @@  enum {
 	STATE_SENT,		/* Do not change state/UUIDs while this is set */
 	CALLBACK_PENDING,	/* Whether we have a call_usermodehelper(, UMH_WAIT_PROC)
 				 * pending, from drbd worker context.
-				 * If set, bdi_write_congested() returns true,
-				 * so shrink_page_list() would not recurse into,
-				 * and potentially deadlock on, this drbd worker.
 				 */
 	DISCONNECT_SENT,
 
--- a/drivers/block/drbd/drbd_req.c~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/drivers/block/drbd/drbd_req.c
@@ -909,8 +909,7 @@  static bool remote_due_to_read_balancing
 
 	switch (rbm) {
 	case RB_CONGESTED_REMOTE:
-		return bdi_read_congested(
-			device->ldev->backing_bdev->bd_disk->bdi);
+		return 0;
 	case RB_LEAST_PENDING:
 		return atomic_read(&device->local_cnt) >
 			atomic_read(&device->ap_pending_cnt) + atomic_read(&device->rs_pending_cnt);
--- a/fs/ext2/ialloc.c~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/fs/ext2/ialloc.c
@@ -170,11 +170,6 @@  static void ext2_preread_inode(struct in
 	unsigned long offset;
 	unsigned long block;
 	struct ext2_group_desc * gdp;
-	struct backing_dev_info *bdi;
-
-	bdi = inode_to_bdi(inode);
-	if (bdi_rw_congested(bdi))
-		return;
 
 	block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
 	gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);
--- a/fs/nilfs2/segbuf.c~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/fs/nilfs2/segbuf.c
@@ -341,18 +341,6 @@  static int nilfs_segbuf_submit_bio(struc
 				   int mode_flags)
 {
 	struct bio *bio = wi->bio;
-	int err;
-
-	if (segbuf->sb_nbio > 0 &&
-	    bdi_write_congested(segbuf->sb_super->s_bdi)) {
-		wait_for_completion(&segbuf->sb_bio_event);
-		segbuf->sb_nbio--;
-		if (unlikely(atomic_read(&segbuf->sb_err))) {
-			bio_put(bio);
-			err = -EIO;
-			goto failed;
-		}
-	}
 
 	bio->bi_end_io = nilfs_end_bio_write;
 	bio->bi_private = segbuf;
@@ -365,10 +353,6 @@  static int nilfs_segbuf_submit_bio(struc
 	wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 	wi->start = wi->end;
 	return 0;
-
- failed:
-	wi->bio = NULL;
-	return err;
 }
 
 /**
--- a/fs/xfs/xfs_buf.c~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/fs/xfs/xfs_buf.c
@@ -843,9 +843,6 @@  xfs_buf_readahead_map(
 {
 	struct xfs_buf		*bp;
 
-	if (bdi_read_congested(target->bt_bdev->bd_disk->bdi))
-		return;
-
 	xfs_buf_read_map(target, map, nmaps,
 		     XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
 		     __this_address);
--- a/include/linux/backing-dev.h~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/include/linux/backing-dev.h
@@ -135,11 +135,6 @@  static inline bool writeback_in_progress
 
 struct backing_dev_info *inode_to_bdi(struct inode *inode);
 
-static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
-{
-	return wb->congested & cong_bits;
-}
-
 long congestion_wait(int sync, long timeout);
 
 static inline bool mapping_can_writeback(struct address_space *mapping)
@@ -391,27 +386,6 @@  static inline void wb_blkcg_offline(stru
 
 #endif	/* CONFIG_CGROUP_WRITEBACK */
 
-static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
-{
-	return wb_congested(&bdi->wb, cong_bits);
-}
-
-static inline int bdi_read_congested(struct backing_dev_info *bdi)
-{
-	return bdi_congested(bdi, 1 << WB_sync_congested);
-}
-
-static inline int bdi_write_congested(struct backing_dev_info *bdi)
-{
-	return bdi_congested(bdi, 1 << WB_async_congested);
-}
-
-static inline int bdi_rw_congested(struct backing_dev_info *bdi)
-{
-	return bdi_congested(bdi, (1 << WB_sync_congested) |
-				  (1 << WB_async_congested));
-}
-
 const char *bdi_dev_name(struct backing_dev_info *bdi);
 
 #endif	/* _LINUX_BACKING_DEV_H */
--- a/mm/vmscan.c~remove-bdi_congested-and-wb_congested-and-related-functions
+++ a/mm/vmscan.c
@@ -2364,9 +2364,7 @@  static unsigned int move_pages_to_lru(st
  */
 static int current_may_throttle(void)
 {
-	return !(current->flags & PF_LOCAL_THROTTLE) ||
-		current->backing_dev_info == NULL ||
-		bdi_write_congested(current->backing_dev_info);
+	return !(current->flags & PF_LOCAL_THROTTLE);
 }
 
 /*