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writeback: make writeback_control.nr_to_write straight

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Pass struct wb_writeback_work all the way down to writeback_sb_inodes(),
and initialize the struct writeback_control there.

struct writeback_control is basically designed to control writeback of a
single file, but we keep abuse it for writing multiple files in
writeback_sb_inodes() and its callers.

It immediately clean things up, e.g. suddenly wbc.nr_to_write vs
work->nr_pages starts to make sense, and instead of saving and restoring
pages_skipped in writeback_sb_inodes it can always start with a clean
zero value.

It also makes a neat IO pattern change: large dirty files are now
written in the full 4MB writeback chunk size, rather than whatever
remained quota in wbc->nr_to_write.

Acked-by: Jan Kara <jack@suse.cz>
Proposed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
This commit is contained in:
Wu Fengguang
2011-05-04 19:54:37 -06:00
parent 36715cef07
commit d46db3d582
6 changed files with 148 additions and 129 deletions
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17
mm/page-writeback.c
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@@ -491,13 +491,6 @@ static void balance_dirty_pages(struct address_space *mapping,
struct backing_dev_info *bdi = mapping->backing_dev_info;
for (;;) {
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
.older_than_this = NULL,
.nr_to_write = write_chunk,
.range_cyclic = 1,
};
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
nr_writeback = global_page_state(NR_WRITEBACK);
@@ -559,17 +552,17 @@ static void balance_dirty_pages(struct address_space *mapping,
* threshold otherwise wait until the disk writes catch
* up.
*/
trace_wbc_balance_dirty_start(&wbc, bdi);
trace_balance_dirty_start(bdi);
if (bdi_nr_reclaimable > bdi_thresh) {
writeback_inodes_wb(&bdi->wb, &wbc);
pages_written += write_chunk - wbc.nr_to_write;
trace_wbc_balance_dirty_written(&wbc, bdi);
pages_written += writeback_inodes_wb(&bdi->wb,
write_chunk);
trace_balance_dirty_written(bdi, pages_written);
if (pages_written >= write_chunk)
break; /* We've done our duty */
}
trace_wbc_balance_dirty_wait(&wbc, bdi);
__set_current_state(TASK_UNINTERRUPTIBLE);
io_schedule_timeout(pause);
trace_balance_dirty_wait(bdi);
/*
* Increase the delay for each loop, up to our previous