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, 10 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 8c81e7b14d53..45af003865d2 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1303,7 +1303,6 @@ static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
 static int cifs_writepages(struct address_space *mapping,
                            struct writeback_control *wbc)
 {
-        struct backing_dev_info *bdi = mapping->backing_dev_info;
         unsigned int bytes_to_write;
         unsigned int bytes_written;
         struct cifs_sb_info *cifs_sb;
@@ -1326,15 +1325,6 @@ static int cifs_writepages(struct address_space *mapping,
         int scanned = 0;
         int xid, long_op;
 
-        /*
-         * BB: Is this meaningful for a non-block-device file system?
-         * If it is, we should test it again after we do I/O
-         */
-        if (wbc->nonblocking && bdi_write_congested(bdi)) {
-                wbc->encountered_congestion = 1;
-                return 0;
-        }
-
         cifs_sb = CIFS_SB(mapping->host->i_sb);
 
         /*