From: NeilBrown <neilb@suse.de>
Date: Sat, 31 Jul 2010 00:00:22 +0000 (+1000)
Subject: Break linkage between inode and dblock at earliest opportunity.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=b858851d50fc1b79008f956deb8c9d22057239d7;p=LaFS.git

Break linkage between inode and dblock at earliest opportunity.

clear_inode is the first chance to break this linkage,
so do it there.
It is still possible for lafs_iget to get a new inode before
clear_inode has completed, so we need to do the same
test/clear in lafs_iget if b->my_inode is found to be non-NULL;

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/index.c b/index.c
index 4c86d6a..ceda443 100644
--- a/index.c
+++ b/index.c
@@ -1053,6 +1053,7 @@ void lafs_refile(struct block *b, int dec)
 		     test_bit(I_Destroyed, &LAFSI(in)->iflags))) {
 			dblk(b)->my_inode = NULL;
 			LAFSI(in)->dblock = NULL;
+			LAFSI(in)->iblock = NULL;
 			spin_unlock(&lafs_hash_lock);
 			if (test_bit(I_Destroyed, &LAFSI(in)->iflags))
 				lafs_destroy_inode(in);
diff --git a/inode.c b/inode.c
index 0db0b49..52f5d99 100644
--- a/inode.c
+++ b/inode.c
@@ -65,6 +65,7 @@ lafs_iget(struct super_block *sb, ino_t inum, int async)
 {
 	/* find, and load if needed, this inum */
 	struct inode *ino = NULL;
+	struct inode *oldino;
 	struct datablock *b = NULL;
 	struct inode *inodefile;
 	struct sb_key *k;
@@ -155,15 +156,25 @@ lafs_iget(struct super_block *sb, ino_t inum, int async)
 	if (err)
 		goto err;
 
-	if (b->my_inode) {
+	oldino = b->my_inode;
+	if (oldino) {
 		/* The inode is new, but the block thinks it has an
 		 * old inode, so we must be in the process of destroying
 		 * the old one.
 		 * So fail the lookup without even looking at the content
 		 * of the block (Which might not be clear yet).
 		 */
-		err = -ENOENT;
-		goto err;
+		spin_lock(&oldino->i_data.private_lock);
+		if (!test_bit(I_Deleting, &LAFSI(oldino)->iflags)) {
+			b->my_inode = NULL;
+			LAFSI(oldino)->dblock = NULL;
+			LAFSI(oldino)->iblock = NULL;
+		}
+		spin_unlock(&oldino->i_data.private_lock);
+		if (b->my_inode) {
+			err = -ENOENT;
+			goto err;
+		}
 	}
 
 	err = lafs_import_inode(ino, b);
@@ -578,6 +589,24 @@ void lafs_clear_inode(struct inode *ino)
 
 	li->type = 0;
 
+	/* Now is a good time to break the linkage between
+	 * inode and dblock - but node if the file is
+	 * being deleted
+	 */
+	if (!test_bit(I_Deleting, &LAFSI(ino)->iflags)) {
+		struct datablock *db;
+		spin_lock(&ino->i_data.private_lock);
+		db = LAFSI(ino)->dblock;
+		if (db) {
+			struct indexblock *ib = LAFSI(ino)->iblock;
+			LAFS_BUG(ib && atomic_read(&ib->b.refcnt), &db->b);
+			db->my_inode = NULL;
+			LAFSI(ino)->dblock = NULL;
+			LAFSI(ino)->iblock = NULL;
+		}
+		spin_unlock(&ino->i_data.private_lock);
+	}
+
 	/* FIXME release quota inodes if filesystem */
 }