From: NeilBrown <neilb@suse.de>
Date: Mon, 28 Sep 2009 00:16:13 +0000 (+1000)
Subject: Handle index blocks becoming empty better.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=ec1227ccfc17b853dfe758694147e453a662640b;p=LaFS.git

Handle index blocks becoming empty better.

MORE TEXT HERE
---

diff --git a/index.c b/index.c
index 5104687..7d9ec0d 100644
--- a/index.c
+++ b/index.c
@@ -1305,6 +1305,7 @@ lafs_leaf_find(struct inode *inode, u32 addr, int adopt, u32 *next,
 	BUG_ON(li->dblock == NULL);
 	BUG_ON(atomic_read(&li->dblock->b.refcnt) == 0);
 
+ retry:
 	if (next)
 		*next = 0xFFFFFFFF;
 
@@ -1354,6 +1355,19 @@ lafs_leaf_find(struct inode *inode, u32 addr, int adopt, u32 *next,
 			dprintk("WARN %llu != %llu\n",
 				ib2->b.physaddr, iphys);
 		}
+
+		if (test_bit(B_PhysValid, &ib2->b.flags) &&
+		    ib2->b.physaddr == 0) {
+			/* this block has been invalidated, we must be
+			 * racing with some sort of truncate.
+			 * try again from the top.
+			 * FIXME should wait for something here.
+			 */
+			putiref(ib2, REF);
+			lafs_iounlock_block(&ib->b);
+			putiref(ib, REF);
+			goto retry;
+		}
 #ifdef FIXME
 		if (!(ib2->b.flags & B_Linked)) {
 			struct block *b2 = peer_find(fs, inode->filesys,
diff --git a/modify.c b/modify.c
index c4ccdae..2796c25 100644
--- a/modify.c
+++ b/modify.c
@@ -1790,18 +1790,22 @@ void lafs_incorporate(struct fs *fs, struct indexblock *ib)
 	temp_credits = 0;
 	lafs_space_return(fs, uit.credits);
 
-	/* If this index block is now empty, we clear
-	 * B_Valid so that it doesn't get written out,
-	 * but rather gets allocated as '0'.
+	/* If this internal index block is now empty, we either
+	 * invalidate it or merge it with the first dependent block.
+	 * If it is the first index block in it's parent we need to
+	 * adjust the start of parent and possibly other ancestors,
+	 * and incorporate them immediately.
 	 */
 	if (test_bit(B_Valid, &ib->b.flags) &&
-	    list_empty(&ib->children)) {
-		if (ib->depth == 1 &&
-		    lafs_leaf_next(ib, ib->b.fileaddr) == 0xFFFFFFFF)
-			clear_bit(B_Valid, &ib->b.flags);
-		if (ib->depth > 1 &&
-		    lafs_index_empty(ib))
-			clear_bit(B_Valid, &ib->b.flags);
+	    list_empty(&ib->children) &&
+	    ib->depth > 1 &&
+	    lafs_index_empty(ib)) {
+		struct block *nxt = list_entry(ib->b.siblings.next,
+					       struct block, siblings);
+		if (ib->b.siblings.next != &ib->b.parent->children &&
+		    test_bit(B_PrimaryRef, &nxt->flags)) {
+			/* */
+		}
 	}
 }