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

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
......@@ -438,7 +438,6 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb,
*/
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;
......
......@@ -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);
......
......@@ -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 @@ static int ceph_writepages_start(struct address_space *mapping,
rc = 0; /* vfs expects us to return 0 */
ceph_put_snap_context(snapc);
dout("writepages done, rc = %d\n", rc);
out_final:
return rc;
}
......
......@@ -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);
/*
......
......@@ -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);
......
......@@ -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;
......
......@@ -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)) {
......
......@@ -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;
}
......
......@@ -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)
......
......@@ -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)
......
......@@ -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;
......
......@@ -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,
};
......
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