From: NeilBrown <neilb@suse.de>
Date: Sat, 14 Aug 2010 12:25:38 +0000 (+1000)
Subject: Check if dirblock can be orphan before making it one.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=4ce23b007d7767c9f6c0a7e0fdf6c53671ac4b9e;p=LaFS.git

Check if dirblock can be orphan before making it one.

Only certain sorts of deletions can make a directory block
into and orphan - check them out before committing resources.

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

diff --git a/dir.c b/dir.c
index b2df67a..50a7374 100644
--- a/dir.c
+++ b/dir.c
@@ -185,7 +185,6 @@ struct dirop_handle {
  * This is split into pre_create and commit_create
  * We already know that the name doesn't exist so a lookup will fail,
  * but will find the right place in the tree.
- * FIXME cache the results of the prior lookup??
  * pre_create allocates blocks as needed and stores info in the dirop_handle.
  * commit_create finalises the create and cannot fail.
  */
@@ -387,7 +386,7 @@ dir_delete_prepare(struct fs *fs, struct inode *dir,
 	       const char *name, int nlen, struct dirop_handle *doh)
 {
 	struct datablock *dirblk;
-	int err;
+	int orphan = 0;
 
 	doh->dirent_block =
 		dirblk = dir_lookup_blk(dir, name, nlen, &doh->index,
@@ -408,11 +407,33 @@ dir_delete_prepare(struct fs *fs, struct inode *dir,
 	/* i_mutex protect us now, so don't need to maintain the lock */
 	lafs_iounlock_block(&dirblk->b);
 
-	/* FIXME should I check if the orphanage is needed
-	 * before committing this block to it?
+	/* Only make this block an orphan if there is a real
+	 * possibilitiy.
+	 * i.e. one of
+	 *    We found the last possible entry
+	 *    We found the first entry
+	 *    We found the only entry (in which case we found the first)
+	 *    First entry is deleted
 	 */
-	err = lafs_make_orphan(fs, doh->dirent_block, dir);
-	return err;
+	if (((doh->hash+1) & MaxDirHash) == doh->dirent_block->b.fileaddr)
+		/* Last possible entry is being remove */
+		orphan=1;
+	if (!orphan) {
+		u32 seed = LAFSI(dir)->md.file.seed;
+		u8 firstpiece = 0;
+		struct dir_ent de;
+		char bits = dir->i_blkbits - 8;
+		char *buf = map_dblock(dirblk);
+		lafs_dir_find(buf, bits, seed, 0, &firstpiece);
+		if (doh->index == firstpiece ||
+		    lafs_dir_extract(buf, bits, &de,
+				     firstpiece, NULL)->target == 0)
+			orphan = 1;
+		unmap_dblock(dirblk, buf);
+	}
+	if (orphan)
+		return lafs_make_orphan(fs, doh->dirent_block, dir);
+	return 0;
 }
 
 static void
@@ -1382,7 +1403,7 @@ int lafs_dir_handle_orphan(struct datablock *b)
 	 * and remove the unanchor.
 	 */
 	lafs_dir_find(buf, bits, seed, 0, &firstpiece);
-	hash = LAFSI(dir)->md.file.seed;
+	hash = seed;
 	if (firstpiece &&
 	    lafs_dir_extract(buf, bits, &de, firstpiece, &hash)->target == 0 &&
 	    lafs_dir_find(buf, bits, seed, hash+1, &piece) == 0) {