writeback: remove nonblocking/encountered_congestion references
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!
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>
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 722743b..15690bb 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -438,7 +438,6 @@
*/
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 @@
}
wbc->nr_to_write -= ret;
- if (wbc->nonblocking && bdi_write_congested(bdi))
- wbc->encountered_congestion = 1;
_leave(" = 0");
return 0;
@@ -469,7 +466,6 @@
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 @@
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 @@
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;
diff --git a/fs/buffer.c b/fs/buffer.c
index 7f0b9b0..ec21a92 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1706,7 +1706,7 @@
* 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);
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 51bcc5c..e9c874a 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -591,7 +591,6 @@
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 @@
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 @@
rc = 0; /* vfs expects us to return 0 */
ceph_put_snap_context(snapc);
dout("writepages done, rc = %d\n", rc);
-out_final:
return rc;
}
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 8c81e7b..45af003 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1303,7 +1303,6 @@
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 @@
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);
/*
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index f3b071f..939739c 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -55,7 +55,7 @@
* 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);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 605e292..4c14c17 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -290,9 +290,7 @@
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;
diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index caa7583..c1f9389 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -2438,7 +2438,7 @@
/* 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)) {
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index b552f81..c9af48f 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -1139,8 +1139,7 @@
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;
}