- Fix a bug that has existed since the original softdep implementation.

   When a background copy of a cg is written we complete any work associated
   with that bmsafemap.  If new work has been added to the non-background
   copy of the buffer it will be completed before the next write happens.
   The solution is to do the rollbacks when we make the copy so only those
   dependencies that were present at the time of writing will be completed
   when the background write completes.  This would've resulted in various
   bitmap related corruptions and panics.  It also would've expired journal
   entries early causing journal replay to miss some records.

MFC after:	2 weeks

1 files changed, 27 insertions, 14 deletions

diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
index 55710a7..d188761 100644
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -977,7 +977,7 @@ static	struct freework *newfreework(struct ufsmount *, struct freeblks *,
 	    struct freework *, ufs_lbn_t, ufs2_daddr_t, int, int, int);
 static	int jwait(struct worklist *, int);
 static	struct inodedep *inodedep_lookup_ip(struct inode *);
-static	int bmsafemap_rollbacks(struct bmsafemap *);
+static	int bmsafemap_backgroundwrite(struct bmsafemap *, struct buf *);
 static	struct freefile *handle_bufwait(struct inodedep *, struct workhead *);
 static	void handle_jwork(struct workhead *);
 static	struct mkdir *setup_newdir(struct diradd *, ino_t, ino_t, struct buf *,
@@ -1795,7 +1795,7 @@ softdep_move_dependencies(oldbp, newbp)
 	while ((wk = LIST_FIRST(&oldbp->b_dep)) != NULL) {
 		LIST_REMOVE(wk, wk_list);
 		if (wk->wk_type == D_BMSAFEMAP &&
-		    bmsafemap_rollbacks(WK_BMSAFEMAP(wk)))
+		    bmsafemap_backgroundwrite(WK_BMSAFEMAP(wk), newbp))
 			dirty = 1;
 		if (wktail == 0)
 			LIST_INSERT_HEAD(&newbp->b_dep, wk, wk_list);
@@ -5173,9 +5173,15 @@ jnewblk_merge(new, old, wkhd)
 		return (new);
 	/* Replace a jfreefrag with a jnewblk. */
 	if (new->wk_type == D_JFREEFRAG) {
+		if (WK_JNEWBLK(old)->jn_blkno != WK_JFREEFRAG(new)->fr_blkno)
+			panic("jnewblk_merge: blkno mismatch: %p, %p",
+			    old, new);
 		cancel_jfreefrag(WK_JFREEFRAG(new));
 		return (old);
 	}
+	if (old->wk_type != D_JNEWBLK || new->wk_type != D_JNEWBLK)
+		panic("jnewblk_merge: Bad type: old %d new %d\n",
+		    old->wk_type, new->wk_type);
 	/*
 	 * Handle merging of two jnewblk records that describe
 	 * different sets of fragments in the same block.
@@ -10504,7 +10510,7 @@ initiate_write_bmsafemap(bmsafemap, bp)
 	ino_t ino;
 
 	if (bmsafemap->sm_state & IOSTARTED)
-		panic("initiate_write_bmsafemap: Already started\n");
+		return;
 	bmsafemap->sm_state |= IOSTARTED;
 	/*
 	 * Clear any inode allocations which are pending journal writes.
@@ -10515,10 +10521,6 @@ initiate_write_bmsafemap(bmsafemap, bp)
 		inosused = cg_inosused(cgp);
 		LIST_FOREACH(jaddref, &bmsafemap->sm_jaddrefhd, ja_bmdeps) {
 			ino = jaddref->ja_ino % fs->fs_ipg;
-			/*
-			 * If this is a background copy the inode may not
-			 * be marked used yet.
-			 */
 			if (isset(inosused, ino)) {
 				if ((jaddref->ja_mode & IFMT) == IFDIR)
 					cgp->cg_cs.cs_ndir--;
@@ -10527,7 +10529,7 @@ initiate_write_bmsafemap(bmsafemap, bp)
 				jaddref->ja_state &= ~ATTACHED;
 				jaddref->ja_state |= UNDONE;
 				stat_jaddref++;
-			} else if ((bp->b_xflags & BX_BKGRDMARKER) == 0)
+			} else
 				panic("initiate_write_bmsafemap: inode %ju "
 				    "marked free", (uintmax_t)jaddref->ja_ino);
 		}
@@ -10542,9 +10544,8 @@ initiate_write_bmsafemap(bmsafemap, bp)
 		LIST_FOREACH(jnewblk, &bmsafemap->sm_jnewblkhd, jn_deps) {
 			if (jnewblk_rollback(jnewblk, fs, cgp, blksfree))
 				continue;
-			if ((bp->b_xflags & BX_BKGRDMARKER) == 0)
-				panic("initiate_write_bmsafemap: block %jd "
-				    "marked free", jnewblk->jn_blkno);
+			panic("initiate_write_bmsafemap: block %jd "
+			    "marked free", jnewblk->jn_blkno);
 		}
 	}
 	/*
@@ -11279,12 +11280,24 @@ diradd_inode_written(dap, inodedep)
  * only be called with lk and the buf lock on the cg held.
  */
 static int
-bmsafemap_rollbacks(bmsafemap)
+bmsafemap_backgroundwrite(bmsafemap, bp)
 	struct bmsafemap *bmsafemap;
+	struct buf *bp;
 {
+	int dirty;
 
-	return (!LIST_EMPTY(&bmsafemap->sm_jaddrefhd) | 
-	    !LIST_EMPTY(&bmsafemap->sm_jnewblkhd));
+	dirty = !LIST_EMPTY(&bmsafemap->sm_jaddrefhd) | 
+	    !LIST_EMPTY(&bmsafemap->sm_jnewblkhd);
+	/*
+	 * If we're initiating a background write we need to process the
+	 * rollbacks as they exist now, not as they exist when IO starts.
+	 * No other consumers will look at the contents of the shadowed
+	 * buf so this is safe to do here.
+	 */
+	if (bp->b_xflags & BX_BKGRDMARKER)
+		initiate_write_bmsafemap(bmsafemap, bp);
+
+	return (dirty);
 }
 
 /*