[PATCH 3/6] writeback: make nr_to_write a per-file limit

From: Wu Fengguang
Date: Wed May 04 2011 - 05:29:47 EST


This ensures large dirty files can be written in the full 4MB writeback
chunk size, rather than whatever remained quota in wbc->nr_to_write.

CC: Jan Kara <jack@xxxxxxx>
CC: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/fs-writeback.c | 11 +++++++++++
include/linux/writeback.h | 1 +
2 files changed, 12 insertions(+)

--- linux-next.orig/fs/fs-writeback.c 2011-05-04 16:00:45.000000000 +0800
+++ linux-next/fs/fs-writeback.c 2011-05-04 16:01:00.000000000 +0800
@@ -346,6 +346,8 @@ writeback_single_inode(struct inode *ino
struct writeback_control *wbc)
{
struct address_space *mapping = inode->i_mapping;
+ long per_file_limit = wbc->per_file_limit;
+ long uninitialized_var(nr_to_write);
unsigned dirty;
int ret;

@@ -385,8 +387,16 @@ writeback_single_inode(struct inode *ino
spin_unlock(&inode->i_lock);
spin_unlock(&wb->list_lock);

+ if (per_file_limit) {
+ nr_to_write = wbc->nr_to_write;
+ wbc->nr_to_write = per_file_limit;
+ }
+
ret = do_writepages(mapping, wbc);

+ if (per_file_limit)
+ wbc->nr_to_write += nr_to_write - per_file_limit;
+
/*
* Make sure to wait on the data before writing out the metadata.
* This is important for filesystems that modify metadata on data
@@ -710,6 +720,7 @@ static long wb_writeback(struct bdi_writ

wbc.more_io = 0;
wbc.nr_to_write = write_chunk;
+ wbc.per_file_limit = write_chunk;
wbc.pages_skipped = 0;
wbc.inodes_cleaned = 0;

--- linux-next.orig/include/linux/writeback.h 2011-05-04 16:00:45.000000000 +0800
+++ linux-next/include/linux/writeback.h 2011-05-04 16:01:00.000000000 +0800
@@ -28,6 +28,7 @@ struct writeback_control {
older than this */
long nr_to_write; /* Write this many pages, and decrement
this for each page written */
+ long per_file_limit; /* Write this many pages for one file */
long pages_skipped; /* Pages which were not written */
long inodes_cleaned; /* # of inodes cleaned */



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