Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a8d638e3 authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

[GFS2] Add writepages for "data=writeback" mounts 



It occurred to me that although a gfs2 specific writepages for ordered
writes and journaled data would be tricky, by hooking writepages only
for "data=writeback" mounts we could take advantage of not needing
buffer heads (we don't use them on the read side, nor have we for some
time) and create much larger I/Os for the block layer.

Using blktrace both before and after, its possible to see that for large
I/Os, most of the requests generated through writepages are now 1024
sectors after this patch is applied as opposed to 8 sectors before.

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 222d3960

fs/gfs2/ops_address.c

+27 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/pagevec.h>

#include <linux/mpage.h>

#include <linux/fs.h>

#include <linux/writeback.h>

#include <linux/gfs2_ondisk.h>

#include <linux/lm_interface.h>
@@ -156,6 +157,31 @@ static int gfs2_writepage(struct page *page, struct writeback_control *wbc) 
	return 0;

}



/**

 * gfs2_writepages - Write a bunch of dirty pages back to disk

 * @mapping: The mapping to write

 * @wbc: Write-back control

 *

 * For journaled files and/or ordered writes this just falls back to the

 * kernel's default writepages path for now. We will probably want to change

 * that eventually (i.e. when we look at allocate on flush).

 *

 * For the data=writeback case though we can already ignore buffer heads

 * and write whole extents at once. This is a big reduction in the

 * number of I/O requests we send and the bmap calls we make in this case.

 */

int gfs2_writepages(struct address_space *mapping, struct writeback_control *wbc)

{

	struct inode *inode = mapping->host;

	struct gfs2_inode *ip = GFS2_I(inode);

	struct gfs2_sbd *sdp = GFS2_SB(inode);



	if (sdp->sd_args.ar_data == GFS2_DATA_WRITEBACK && !gfs2_is_jdata(ip))

		return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);



	return generic_writepages(mapping, wbc);

}



/**

 * stuffed_readpage - Fill in a Linux page with stuffed file data

 * @ip: the inode
@@ -757,6 +783,7 @@ int gfs2_releasepage(struct page *page, gfp_t gfp_mask) 


const struct address_space_operations gfs2_file_aops = {

	.writepage = gfs2_writepage,

	.writepages = gfs2_writepages,

	.readpage = gfs2_readpage,

	.readpages = gfs2_readpages,

	.sync_page = block_sync_page,