writeback: remove nonblocking/encountered_congestion references

This removes more dead code that was somehow missed by commit 0d99519efef
(writeback: remove unused nonblocking and congestion checks).  There are
no behavior change except for the removal of two entries from one of the
ext4 tracing interface.

The nonblocking checks in ->writepages are no longer used because the
flusher now prefer to block on get_request_wait() than to skip inodes on
IO congestion.  The latter will lead to more seeky IO.

The nonblocking checks in ->writepage are no longer used because it's
redundant with the WB_SYNC_NONE check.

We no long set ->nonblocking in VM page out and page migration, because
a) it's effectively redundant with WB_SYNC_NONE in current code
b) it's old semantic of "Don't get stuck on request queues" is mis-behavior:
   that would skip some dirty inodes on congestion and page out others, which
   is unfair in terms of LRU age.

Inspired by Christoph Hellwig. Thanks!

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: David Howells <dhowells@redhat.com>
Cc: Sage Weil <sage@newdream.net>
Cc: Steve French <sfrench@samba.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 9 deletions

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 51bcc5c..e9c874a 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -591,7 +591,6 @@ static int ceph_writepages_start(struct address_space *mapping,
 				 struct writeback_control *wbc)
 {
 	struct inode *inode = mapping->host;
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_fs_client *fsc;
 	pgoff_t index, start, end;
@@ -633,13 +632,6 @@ static int ceph_writepages_start(struct address_space *mapping,
 
 	pagevec_init(&pvec, 0);
 
-	/* ?? */
-	if (wbc->nonblocking && bdi_write_congested(bdi)) {
-		dout(" writepages congested\n");
-		wbc->encountered_congestion = 1;
-		goto out_final;
-	}
-
 	/* where to start/end? */
 	if (wbc->range_cyclic) {
 		start = mapping->writeback_index; /* Start from prev offset */
@@ -885,7 +877,6 @@ out:
 		rc = 0;  /* vfs expects us to return 0 */
 	ceph_put_snap_context(snapc);
 	dout("writepages done, rc = %d\n", rc);
-out_final:
 	return rc;
 }