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, 1 insertions, 62 deletions

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 1f855a74a4ec..e0d0db5f7fc6 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -517,67 +517,6 @@ out:
 	return ret;
 }
 
-/**
- * map_journal_extents - create a reusable "extent" mapping from all logical
- * blocks to all physical blocks for the given journal.  This will save
- * us time when writing journal blocks.  Most journals will have only one
- * extent that maps all their logical blocks.  That's because gfs2.mkfs
- * arranges the journal blocks sequentially to maximize performance.
- * So the extent would map the first block for the entire file length.
- * However, gfs2_jadd can happen while file activity is happening, so
- * those journals may not be sequential.  Less likely is the case where
- * the users created their own journals by mounting the metafs and
- * laying it out.  But it's still possible.  These journals might have
- * several extents.
- *
- * TODO: This should be done in bigger chunks rather than one block at a time,
- *       but since it's only done at mount time, I'm not worried about the
- *       time it takes.
- */
-static int map_journal_extents(struct gfs2_sbd *sdp)
-{
-	struct gfs2_jdesc *jd = sdp->sd_jdesc;
-	unsigned int lb;
-	u64 db, prev_db; /* logical block, disk block, prev disk block */
-	struct gfs2_inode *ip = GFS2_I(jd->jd_inode);
-	struct gfs2_journal_extent *jext = NULL;
-	struct buffer_head bh;
-	int rc = 0;
-
-	prev_db = 0;
-
-	for (lb = 0; lb < i_size_read(jd->jd_inode) >> sdp->sd_sb.sb_bsize_shift; lb++) {
-		bh.b_state = 0;
-		bh.b_blocknr = 0;
-		bh.b_size = 1 << ip->i_inode.i_blkbits;
-		rc = gfs2_block_map(jd->jd_inode, lb, &bh, 0);
-		db = bh.b_blocknr;
-		if (rc || !db) {
-			printk(KERN_INFO "GFS2 journal mapping error %d: lb="
-			       "%u db=%llu\n", rc, lb, (unsigned long long)db);
-			break;
-		}
-		if (!prev_db || db != prev_db + 1) {
-			jext = kzalloc(sizeof(struct gfs2_journal_extent),
-				       GFP_KERNEL);
-			if (!jext) {
-				printk(KERN_INFO "GFS2 error: out of memory "
-				       "mapping journal extents.\n");
-				rc = -ENOMEM;
-				break;
-			}
-			jext->dblock = db;
-			jext->lblock = lb;
-			jext->blocks = 1;
-			list_add_tail(&jext->extent_list, &jd->extent_list);
-		} else {
-			jext->blocks++;
-		}
-		prev_db = db;
-	}
-	return rc;
-}
-
 static void gfs2_others_may_mount(struct gfs2_sbd *sdp)
 {
 	char *message = "FIRSTMOUNT=Done";
@@ -779,7 +718,7 @@ static int init_journal(struct gfs2_sbd *sdp, int undo)
 		atomic_set(&sdp->sd_log_thresh2, 4*sdp->sd_jdesc->jd_blocks/5);
 
 		/* Map the extents for this journal's blocks */
-		map_journal_extents(sdp);
+		gfs2_map_journal_extents(sdp, sdp->sd_jdesc);
 	}
 	trace_gfs2_log_blocks(sdp, atomic_read(&sdp->sd_log_blks_free));