writeback: remove nonblocking/encountered_congestion references

This removes more dead code that was somehow missed by commit 0d99519efe
(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 <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: David Howells <[email protected]>
Cc: Sage Weil <[email protected]>
Cc: Steve French <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Wu Fengguang 2010-10-26 14:21:26 -07:00 • committed by Linus Torvalds
commit 1b430beee5
12 changed files with 11 additions and 52 deletions

View file

@ -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);
/*