GFS2: Clean up journal extent mapping

This patch fixes a long standing issue in mapping the journal
extents. Most journals will consist of only a single extent,
and although the cache took account of that by merging extents,
it did not actually map large extents, but instead was doing a
block by block mapping. Since the journal was only being mapped
on mount, this was not normally noticeable.

With the updated code, it is now possible to use the same extent
mapping system during journal recovery (which will be added in a
later patch). This will allow checking of the integrity of the
journal before any reply of the journal content is attempted. For
this reason the code is moving to bmap.c, since it will be used
more widely in due course.

An exercise left for the reader is to compare the new function
gfs2_map_journal_extents() with gfs2_write_alloc_required()

Additionally, should there be a failure, the error reporting is
also updated to show more detail about what went wrong.

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

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index d0c3928b2dea..456d8fa9da2b 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -485,7 +485,7 @@ struct gfs2_trans {
 };
 
 struct gfs2_journal_extent {
-	struct list_head extent_list;
+	struct list_head list;
 
 	unsigned int lblock; /* First logical block */
 	u64 dblock; /* First disk block */
@@ -495,6 +495,7 @@ struct gfs2_journal_extent {
 struct gfs2_jdesc {
 	struct list_head jd_list;
 	struct list_head extent_list;
+	unsigned int nr_extents;
 	struct work_struct jd_work;
 	struct inode *jd_inode;
 	unsigned long jd_flags;