GFS2: Use ->writepages for ordered writes

Instead of using a list of buffers to write ahead of the journal
flush, this now uses a list of inodes and calls ->writepages
via filemap_fdatawrite() in order to achieve the same thing. For
most use cases this results in a shorter ordered write list,
as well as much larger i/os being issued.

The ordered write list is sorted by inode number before writing
in order to retain the disk block ordering between inodes as
per the previous code.

The previous ordered write code used to conflict in its assumptions
about how to write out the disk blocks with mpage_writepages()
so that with this updated version we can also use mpage_writepages()
for GFS2's ordered write, writepages implementation. So we will
also send larger i/os from writeback too.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/gfs2/log.h b/fs/gfs2/log.h
index 3fd5215ea25f..3566f35915e0 100644
--- a/fs/gfs2/log.h
+++ b/fs/gfs2/log.h
@@ -48,6 +48,18 @@ static inline void gfs2_log_pointers_init(struct gfs2_sbd *sdp,
 	sdp->sd_log_head = sdp->sd_log_tail = value;
 }
 
+static inline void gfs2_ordered_add_inode(struct gfs2_inode *ip)
+{
+	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+
+	if (!test_bit(GIF_ORDERED, &ip->i_flags)) {
+		spin_lock(&sdp->sd_ordered_lock);
+		if (!test_and_set_bit(GIF_ORDERED, &ip->i_flags))
+			list_add(&ip->i_ordered, &sdp->sd_log_le_ordered);
+		spin_unlock(&sdp->sd_ordered_lock);
+	}
+}
+extern void gfs2_ordered_del_inode(struct gfs2_inode *ip);
 extern unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
 			    unsigned int ssize);