[GFS2] invalid metadata block - REVISED

This is for bugzilla bug #248176: GFS2: invalid metadata block

Patches 1 thru 3 were accepted upstream, but there were problems
with 4 and 5.  Those issues have been resolved and now the recovery
tests are passing without errors.  This code has gone through
41 * 3 successful gfs2 recovery tests before it hit an
unrelated (openais) problem.

This is a complete rewrite of patch 4 for bug #248176.

Part of the problem was that inodes were being recycled
before their buffers were flushed to the journal logs.
Another problem was that the clone bitmaps were being
searched for deleted inodes to recycle, but only the
"real" bitmaps should be searched for that purpose.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

fs/gfs2/rgrp.c

@@ -865,12 +865,15 @@ static struct inode *try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked)
 	struct inode *inode;
 	u32 goal = 0, block;
 	u64 no_addr;
+	struct gfs2_sbd *sdp = rgd->rd_sbd;
 
 	for(;;) {
 		if (goal >= rgd->rd_data)
 			break;
+		down_write(&sdp->sd_log_flush_lock);
 		block = rgblk_search(rgd, goal, GFS2_BLKST_UNLINKED,
 				     GFS2_BLKST_UNLINKED);
+		up_write(&sdp->sd_log_flush_lock);
 		if (block == BFITNOENT)
 			break;
 		/* rgblk_search can return a block < goal, so we need to
@@ -1295,7 +1298,9 @@ static u32 rgblk_search(struct gfs2_rgrpd *rgd, u32 goal,
 	   allocatable block anywhere else, we want to be able wrap around and
 	   search in the first part of our first-searched bit block.  */
 	for (x = 0; x <= length; x++) {
-		if (bi->bi_clone)
+		/* The GFS2_BLKST_UNLINKED state doesn't apply to the clone
+		   bitmaps, so we must search the originals for that. */
+		if (old_state != GFS2_BLKST_UNLINKED && bi->bi_clone)
 			blk = gfs2_bitfit(rgd, bi->bi_clone + bi->bi_offset,
 					  bi->bi_len, goal, old_state);
 		else