This removes more dead code that was somehow missed by commit 0d99519efef
(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!
CC: Theodore Ts'o <tytso@xxxxxxx>
CC: David Howells <dhowells@xxxxxxxxxx>
CC: Sage Weil <sage@xxxxxxxxxxxx>
CC: Steve French <sfrench@xxxxxxxxx>
CC: Chris Mason <chris.mason@xxxxxxxxxx>
CC: Jens Axboe <axboe@xxxxxxxxx>
CC: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
Andrew: this passed allmodconfig and allyesconfig compile tests.
This effectively removes all references to wbc->nonblocking and
wbc->encountered_congestion. The NFS git tree has a standalone patch
to remove one wbc->nonblocking reference. To avoid merge conflicts,
the removal of nonblocking/encountered_congestion definitions need to
be delayed for one more kernel release.
fs/afs/write.c | 19 +------------------
fs/buffer.c | 2 +-
fs/ceph/addr.c | 9 ---------
fs/cifs/file.c | 11 -----------
fs/gfs2/meta_io.c | 2 +-
fs/nfs/write.c | 6 ++----
fs/reiserfs/inode.c | 2 +-
fs/xfs/linux-2.6/xfs_aops.c | 3 +--
include/trace/events/ext4.h | 8 +++++---
include/trace/events/writeback.h | 2 --
mm/migrate.c | 1 -
mm/vmscan.c | 1 -
12 files changed, 12 insertions(+), 54 deletions(-)
Index: mmotm/fs/afs/write.c
===================================================================
--- mmotm.orig/fs/afs/write.c
+++ mmotm/fs/afs/write.c
@@ -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, str
}
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
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
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
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;
Index: mmotm/fs/buffer.c
===================================================================
--- mmotm.orig/fs/buffer.c
+++ mmotm/fs/buffer.c
@@ -1682,7 +1682,7 @@ static int __block_write_full_page(struc
* 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);
Index: mmotm/fs/ceph/addr.c
===================================================================
--- mmotm.orig/fs/ceph/addr.c
+++ mmotm/fs/ceph/addr.c
@@ -594,7 +594,6 @@ static int ceph_writepages_start(struct
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_client *client;
pgoff_t index, start, end;
@@ -636,13 +635,6 @@ static int ceph_writepages_start(struct
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 */
@@ -887,7 +879,6 @@ 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;
}
Index: mmotm/fs/cifs/file.c
===================================================================
--- mmotm.orig/fs/cifs/file.c
+++ mmotm/fs/cifs/file.c
@@ -1338,7 +1338,6 @@ static int cifs_partialpagewrite(struct
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;
@@ -1380,16 +1379,6 @@ static int cifs_writepages(struct addres
return generic_writepages(mapping, wbc);
- /*
- * 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;
- kfree(iov);
- return 0;
- }
-
xid = GetXid();
pagevec_init(&pvec, 0);
Index: mmotm/fs/gfs2/meta_io.c
===================================================================
--- mmotm.orig/fs/gfs2/meta_io.c
+++ mmotm/fs/gfs2/meta_io.c
@@ -55,7 +55,7 @@ static int gfs2_aspace_writepage(struct
* 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);
Index: mmotm/fs/nfs/write.c
===================================================================
--- mmotm.orig/fs/nfs/write.c
+++ mmotm/fs/nfs/write.c
@@ -292,9 +292,7 @@ static int nfs_do_writepage(struct page
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;
Index: mmotm/fs/reiserfs/inode.c
===================================================================
--- mmotm.orig/fs/reiserfs/inode.c
+++ mmotm/fs/reiserfs/inode.c
@@ -2437,7 +2437,7 @@ static int reiserfs_write_full_page(stru
/* 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)) {
Index: mmotm/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- mmotm.orig/fs/xfs/linux-2.6/xfs_aops.c
+++ mmotm/fs/xfs/linux-2.6/xfs_aops.c
@@ -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;
}
Index: mmotm/include/trace/events/ext4.h
===================================================================
--- mmotm.orig/include/trace/events/ext4.h
+++ mmotm/include/trace/events/ext4.h
@@ -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)
Index: mmotm/include/trace/events/writeback.h
===================================================================
--- mmotm.orig/include/trace/events/writeback.h
+++ mmotm/include/trace/events/writeback.h
@@ -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)
Index: mmotm/mm/migrate.c
===================================================================
--- mmotm.orig/mm/migrate.c
+++ mmotm/mm/migrate.c
@@ -431,7 +431,6 @@ static int writeout(struct address_space
.nr_to_write = 1,
.range_start = 0,
.range_end = LLONG_MAX,
- .nonblocking = 1,
.for_reclaim = 1
};
int rc;
Index: mmotm/mm/vmscan.c
===================================================================
--- mmotm.orig/mm/vmscan.c
+++ mmotm/mm/vmscan.c
@@ -391,7 +391,6 @@ static pageout_t pageout(struct page *pa
.nr_to_write = SWAP_CLUSTER_MAX,
.range_start = 0,
.range_end = LLONG_MAX,
- .nonblocking = 1,
.for_reclaim = 1,
};
--
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