ufs_trunc_tindirect(): pass the number of blocks to keep

IOW, the distance of cutoff from the begining of the branch
(in blocks).

That (and the fact that block just prior to cutoff is guaranteed to
be present) allows to tell whether to free triple indirect block
just by looking at the offset.

While we are at it, using u64 for index in the block is wrong -
those should be unsigned int.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ufs/inode.c

@@ -1208,19 +1208,17 @@ static void ufs_trunc_dindirect(struct inode *inode, u64 offset, void *p)
 	UFSD("EXIT: ino %lu\n", inode->i_ino);
 }
 
-static void ufs_trunc_tindirect(struct inode *inode)
+static void ufs_trunc_tindirect(struct inode *inode, u64 offset)
 {
 	struct super_block *sb = inode->i_sb;
 	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
 	struct ufs_inode_info *ufsi = UFS_I(inode);
 	struct ufs_buffer_head * tind_bh;
-	u64 tindirect_block, tmp, i;
+	u64 tmp;
 	void *tind, *p;
-
-	UFSD("ENTER: ino %lu\n", inode->i_ino);
-
-	tindirect_block = (DIRECT_BLOCK > (UFS_NDADDR + uspi->s_apb + uspi->s_2apb))
-		? ((DIRECT_BLOCK - UFS_NDADDR - uspi->s_apb - uspi->s_2apb) >> uspi->s_2apbshift) : 0;
+	bool free_it = !offset;
+	unsigned tindirect_block = offset >> uspi->s_2apbshift;
+	unsigned i;
 
 	p = ufs_get_direct_data_ptr(uspi, ufsi, UFS_TIND_BLOCK);
 	if (!(tmp = ufs_data_ptr_to_cpu(sb, p)))
@@ -1239,11 +1237,7 @@ static void ufs_trunc_tindirect(struct inode *inode)
 			uspi->s_apb + ((i + 1) << uspi->s_2apbshift), tind);
 		ubh_mark_buffer_dirty(tind_bh);
 	}
-	for (i = 0; i < uspi->s_apb; i++)
-		if (!ufs_is_data_ptr_zero(uspi,
-					  ubh_get_data_ptr(uspi, tind_bh, i)))
-			break;
-	if (i >= uspi->s_apb) {
+	if (free_it) {
 		tmp = ufs_data_ptr_to_cpu(sb, p);
 		write_seqlock(&ufsi->meta_lock);
 		ufs_data_ptr_clear(uspi, p);
@@ -1252,13 +1246,11 @@ static void ufs_trunc_tindirect(struct inode *inode)
 		ubh_bforget(tind_bh);
 		ufs_free_blocks(inode, tmp, uspi->s_fpb);
 		mark_inode_dirty(inode);
-		tind_bh = NULL;
+		return;
 	}
-	if (IS_SYNC(inode) && tind_bh && ubh_buffer_dirty(tind_bh))
+	if (IS_SYNC(inode) && ubh_buffer_dirty(tind_bh))
 		ubh_sync_block(tind_bh);
 	ubh_brelse (tind_bh);
-
-	UFSD("EXIT: ino %lu\n", inode->i_ino);
 }
 
 static int ufs_alloc_lastblock(struct inode *inode, loff_t size)
@@ -1349,8 +1341,10 @@ static void __ufs_truncate_blocks(struct inode *inode)
 	case 3:
 		ufs_trunc_dindirect(inode, UFS_IND_BLOCK + uspi->s_apb,
 			    ufs_get_direct_data_ptr(uspi, ufsi, UFS_DIND_BLOCK));
+		ufs_trunc_tindirect(inode, 0);
+		break;
 	case 4:
-		ufs_trunc_tindirect(inode);
+		ufs_trunc_tindirect(inode, DIRECT_BLOCK - UFS_NDADDR - uspi->s_apb - uspi->s_2apb);
 	}
 	ufsi->i_lastfrag = DIRECT_FRAGMENT;
 	mutex_unlock(&ufsi->truncate_mutex);