• W
    writeback: remove nonblocking/encountered_congestion references · 1b430bee
    Wu Fengguang 提交于
    This removes more dead code that was somehow missed by commit 0d99519e
    (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: NWu 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: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    1b430bee
writeback.h 4.5 KB