+ remove-bdi_congested-and-wb_congested-and-related-functions.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm/fs: remove bdi_congested() and wb_congested() and related functions
has been added to the -mm tree.  Its filename is
     remove-bdi_congested-and-wb_congested-and-related-functions.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/remove-bdi_congested-and-wb_congested-and-related-functions.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/remove-bdi_congested-and-wb_congested-and-related-functions.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: NeilBrown <neilb@suse.de>
Subject: mm/fs: remove bdi_congested() and wb_congested() and related functions

These functions are no longer useful as the only bdis that report
congestion are in ceph, fuse, and nfs.  None of those bdis can be the
target of the calls in drbd, ext2, nilfs2, or xfs.

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.

Link: https://lkml.kernel.org/r/164325158955.29787.4769373293473421057.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/drbd/drbd_int.h |    3 ---
 drivers/block/drbd/drbd_req.c |    3 +--
 fs/ext2/ialloc.c              |    2 --
 fs/nilfs2/segbuf.c            |   11 -----------
 fs/xfs/xfs_buf.c              |    3 ---
 include/linux/backing-dev.h   |   26 --------------------------
 mm/vmscan.c                   |    4 +---
 7 files changed, 2 insertions(+), 50 deletions(-)

--- 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
@@ -173,8 +173,6 @@ static void ext2_preread_inode(struct in
 	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
@@ -343,17 +343,6 @@ static int nilfs_segbuf_submit_bio(struc
 	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;
 	bio_set_op_attrs(bio, mode, mode_flags);
--- 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
@@ -2362,9 +2362,7 @@ 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);
 }
 
 /*
_

Patches currently in -mm which might be from neilb@suse.de are

remove-inode_congested.patch
remove-bdi_congested-and-wb_congested-and-related-functions.patch
f2fs-change-retry-waiting-for-f2fs_write_single_data_page.patch
f2f2-replace-some-congestion_wait-calls-with-io_schedule_timeout.patch
cephfs-dont-set-clear-bdi_congestion.patch
fuse-dont-set-clear-bdi_congested.patch
nfs-remove-congestion-control.patch
block-bfq-ioschedc-use-false-rather-than-blk_rw_async.patch
remove-congestion-tracking-framework.patch
mm-discard-__gfp_atomic.patch