Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a8d638e30e768adc6956541f79f7bf05139ba475
Commit:     a8d638e30e768adc6956541f79f7bf05139ba475
Parent:     222d396092acc11b4af03bede309aa066945e920
Author:     Steven Whitehouse <[EMAIL PROTECTED]>
AuthorDate: Mon Jan 15 13:52:17 2007 +0000
Committer:  Steven Whitehouse <[EMAIL PROTECTED]>
CommitDate: Mon Feb 5 13:37:01 2007 -0500

    [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: Steven Whitehouse <[EMAIL PROTECTED]>
---
 fs/gfs2/ops_address.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 37bfeb9..9ddf975 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -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>
 
@@ -157,6 +158,31 @@ out_ignore:
 }
 
 /**
+ * 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
  * @page: the page
@@ -757,6 +783,7 @@ out:
 
 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,
-
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