Commit 1b430bee authored by Wu Fengguang's avatar Wu Fengguang Committed by Linus Torvalds
Browse files

writeback: remove nonblocking/encountered_congestion references 



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: default avatarWu 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d19d5476

fs/afs/write.c

+1 −18
Original line number Diff line number Diff line
@@ -438,7 +438,6 @@ no_more: 
 */

int afs_writepage(struct page *page, struct writeback_control *wbc)

{

	struct backing_dev_info *bdi = page->mapping->backing_dev_info;

	struct afs_writeback *wb;

	int ret;
@@ -455,8 +454,6 @@ int afs_writepage(struct page *page, struct writeback_control *wbc) 
	}



	wbc->nr_to_write -= ret;

	if (wbc->nonblocking && bdi_write_congested(bdi))

		wbc->encountered_congestion = 1;



	_leave(" = 0");

	return 0;
@@ -469,7 +466,6 @@ static int afs_writepages_region(struct address_space *mapping, 
				 struct writeback_control *wbc,

				 pgoff_t index, pgoff_t end, pgoff_t *_next)

{

	struct backing_dev_info *bdi = mapping->backing_dev_info;

	struct afs_writeback *wb;

	struct page *page;

	int ret, n;
@@ -529,11 +525,6 @@ static int afs_writepages_region(struct address_space *mapping, 


		wbc->nr_to_write -= ret;



		if (wbc->nonblocking && bdi_write_congested(bdi)) {

			wbc->encountered_congestion = 1;

			break;

		}



		cond_resched();

	} while (index < end && wbc->nr_to_write > 0);
@@ -548,24 +539,16 @@ static int afs_writepages_region(struct address_space *mapping, 
int afs_writepages(struct address_space *mapping,

		   struct writeback_control *wbc)

{

	struct backing_dev_info *bdi = mapping->backing_dev_info;

	pgoff_t start, end, next;

	int ret;



	_enter("");



	if (wbc->nonblocking && bdi_write_congested(bdi)) {

		wbc->encountered_congestion = 1;

		_leave(" = 0 [congest]");

		return 0;

	}



	if (wbc->range_cyclic) {

		start = mapping->writeback_index;

		end = -1;

		ret = afs_writepages_region(mapping, wbc, start, end, &next);

		if (start > 0 && wbc->nr_to_write > 0 && ret == 0 &&

		    !(wbc->nonblocking && wbc->encountered_congestion))

		if (start > 0 && wbc->nr_to_write > 0 && ret == 0)

			ret = afs_writepages_region(mapping, wbc, 0, start,

						    &next);

		mapping->writeback_index = next;

fs/buffer.c

+1 −1
Original line number Diff line number Diff line
@@ -1706,7 +1706,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page, 
		 * and kswapd activity, but those code paths have their own

		 * higher-level throttling.

		 */

		if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {

		if (wbc->sync_mode != WB_SYNC_NONE) {

			lock_buffer(bh);

		} else if (!trylock_buffer(bh)) {

			redirty_page_for_writepage(wbc, page);

fs/ceph/addr.c

+0 −9
Original line number Diff line number Diff line
@@ -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;

}

fs/cifs/file.c

+0 −10
Original line number Diff line number Diff line
@@ -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);



	/*

fs/gfs2/meta_io.c

+1 −1
Original line number Diff line number Diff line
@@ -55,7 +55,7 @@ static int gfs2_aspace_writepage(struct page *page, struct writeback_control *wb 
		 * activity, but those code paths have their own higher-level

		 * throttling.

		 */

		if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {

		if (wbc->sync_mode != WB_SYNC_NONE) {

			lock_buffer(bh);

		} else if (!trylock_buffer(bh)) {

			redirty_page_for_writepage(wbc, page);

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