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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 <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>
This commit is contained in:
Wu Fengguang 2010-10-26 14:21:26 -07:00 committed by Linus Torvalds
parent d19d5476f4
commit 1b430beee5
12 changed files with 11 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
fs/afs/write.c
View File

@ -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;

2
fs/buffer.c
View File

@ -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);

9
fs/ceph/addr.c
View File

@ -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;
}

10
fs/cifs/file.c
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);
/*

2
fs/gfs2/meta_io.c
View File

@ -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);

4
fs/nfs/write.c
View File

@ -290,9 +290,7 @@ static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, st
nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
nfs_pageio_cond_complete(pgio, page->index);
ret = nfs_page_async_flush(pgio, page,
wbc->sync_mode == WB_SYNC_NONE ||
wbc->nonblocking != 0);
ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
if (ret == -EAGAIN) {
redirty_page_for_writepage(wbc, page);
ret = 0;

2
fs/reiserfs/inode.c
View File

@ -2438,7 +2438,7 @@ static int reiserfs_write_full_page(struct page *page,
/* from this point on, we know the buffer is mapped to a
* real block and not a direct item
*/
if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
if (wbc->sync_mode != WB_SYNC_NONE) {
lock_buffer(bh);
} else {
if (!trylock_buffer(bh)) {

3
fs/xfs/linux-2.6/xfs_aops.c
View File

@ -1139,8 +1139,7 @@ xfs_vm_writepage(
type = IO_DELAY;
flags = BMAPI_ALLOCATE;
if (wbc->sync_mode == WB_SYNC_NONE &&
wbc->nonblocking)
if (wbc->sync_mode == WB_SYNC_NONE)
flags |= BMAPI_TRYLOCK;
}

8
include/trace/events/ext4.h
View File

@ -242,18 +242,20 @@ TRACE_EVENT(ext4_da_writepages,
__entry->pages_skipped = wbc->pages_skipped;
__entry->range_start = wbc->range_start;
__entry->range_end = wbc->range_end;
__entry->nonblocking = wbc->nonblocking;
__entry->for_kupdate = wbc->for_kupdate;
__entry->for_reclaim = wbc->for_reclaim;
__entry->range_cyclic = wbc->range_cyclic;
__entry->writeback_index = inode->i_mapping->writeback_index;
),
TP_printk("dev %s ino %lu nr_to_write %ld pages_skipped %ld range_start %llu range_end %llu nonblocking %d for_kupdate %d for_reclaim %d range_cyclic %d writeback_index %lu",
TP_printk("dev %s ino %lu nr_to_write %ld pages_skipped %ld "
"range_start %llu range_end %llu "
"for_kupdate %d for_reclaim %d "
"range_cyclic %d writeback_index %lu",
jbd2_dev_to_name(__entry->dev),
(unsigned long) __entry->ino, __entry->nr_to_write,
__entry->pages_skipped, __entry->range_start,
__entry->range_end, __entry->nonblocking,
__entry->range_end,
__entry->for_kupdate, __entry->for_reclaim,
__entry->range_cyclic,
(unsigned long) __entry->writeback_index)

2
include/trace/events/writeback.h
View File

@ -96,8 +96,6 @@ DECLARE_EVENT_CLASS(wbc_class,
__field(long, nr_to_write)
__field(long, pages_skipped)
__field(int, sync_mode)
__field(int, nonblocking)
__field(int, encountered_congestion)
__field(int, for_kupdate)
__field(int, for_background)
__field(int, for_reclaim)

1
mm/migrate.c
View File

@ -497,7 +497,6 @@ static int writeout(struct address_space *mapping, struct page *page)
.nr_to_write = 1,
.range_start = 0,
.range_end = LLONG_MAX,
.nonblocking = 1,
.for_reclaim = 1
};
int rc;

1
mm/vmscan.c
View File

@ -376,7 +376,6 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
.nonblocking = 1,
.for_reclaim = 1,
};