ufs_trunc_..indirect(): more massage towards unifying

Instead of manually checking that the array contains only zeroes,
find the position of the last non-zero (in __ufs_truncate(), where
we can conveniently do that) and use that to tell if there's
any non-zero in the array tail passed to ufs_trunc_...indirect().

The goal of all that clumsiness is to get fold these functions
together.

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

fs/ufs/inode.c

@@ -1069,7 +1069,7 @@ next1:
 }
 
 
-static void ufs_trunc_indirect(struct inode *inode, unsigned *offsets, void *p)
+static void ufs_trunc_indirect(struct inode *inode, unsigned *offsets, int depth2, void *p)
 {
 	struct super_block *sb = inode->i_sb;
 	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
@@ -1078,7 +1078,7 @@ static void ufs_trunc_indirect(struct inode *inode, unsigned *offsets, void *p)
 	u64 tmp, frag_to_free = 0;
 	unsigned free_count = 0;
 	unsigned from = offsets ? *offsets : 0;
-	bool to_free = !offsets || !from;
+	bool to_free = !offsets || !depth2;
 	unsigned i;
 
 	tmp = ufs_data_ptr_to_cpu(sb, p);
@@ -1135,14 +1135,14 @@ static void ufs_trunc_indirect(struct inode *inode, unsigned *offsets, void *p)
 	ubh_brelse (ind_ubh);
 }
 
-static void ufs_trunc_dindirect(struct inode *inode, unsigned *offsets, void *p)
+static void ufs_trunc_dindirect(struct inode *inode, unsigned *offsets, int depth2, void *p)
 {
 	struct super_block *sb = inode->i_sb;
 	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
 	struct ufs_buffer_head *dind_bh;
 	u64 tmp;
 	void *dind;
-	bool free_it = !offsets || !(offsets[0] || offsets[1]);
+	bool free_it = !offsets || !depth2;
 	unsigned dindirect_block = offsets ? *offsets++ : 0;
 	unsigned i;
 
@@ -1162,7 +1162,7 @@ static void ufs_trunc_dindirect(struct inode *inode, unsigned *offsets, void *p)
 		tmp = ufs_data_ptr_to_cpu(sb, dind);
 		if (!tmp)
 			continue;
-		ufs_trunc_indirect(inode, offsets, dind);
+		ufs_trunc_indirect(inode, offsets, depth2 - 1, dind);
 		ubh_mark_buffer_dirty(dind_bh);
 	}
 
@@ -1182,7 +1182,7 @@ static void ufs_trunc_dindirect(struct inode *inode, unsigned *offsets, void *p)
 	ubh_brelse (dind_bh);
 }
 
-static void ufs_trunc_tindirect(struct inode *inode, unsigned *offsets)
+static void ufs_trunc_tindirect(struct inode *inode, unsigned *offsets, int depth2)
 {
 	struct super_block *sb = inode->i_sb;
 	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
@@ -1190,7 +1190,7 @@ static void ufs_trunc_tindirect(struct inode *inode, unsigned *offsets)
 	struct ufs_buffer_head * tind_bh;
 	u64 tmp;
 	void *tind, *p;
-	bool free_it = !offsets || !(offsets[0] || offsets[1] || offsets[2]);
+	bool free_it = !offsets || !depth2;
 	unsigned tindirect_block = offsets ? *offsets++ : 0;
 	unsigned i;
 
@@ -1207,7 +1207,7 @@ static void ufs_trunc_tindirect(struct inode *inode, unsigned *offsets)
 
 	for (i = tindirect_block ; i < uspi->s_apb ; i++, offsets = NULL) {
 		tind = ubh_get_data_ptr(uspi, tind_bh, i);
-		ufs_trunc_dindirect(inode, offsets, tind);
+		ufs_trunc_dindirect(inode, offsets, depth2 - 1, tind);
 		ubh_mark_buffer_dirty(tind_bh);
 	}
 	if (free_it) {
@@ -1303,31 +1303,40 @@ static void __ufs_truncate_blocks(struct inode *inode)
 	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
 	unsigned offsets[4];
 	int depth = ufs_block_to_path(inode, DIRECT_BLOCK, offsets);
+	int depth2;
+
+	if (!depth)
+		return;
+
+	/* find the last non-zero in offsets[] */
+	for (depth2 = depth - 1; depth2; depth2--)
+		if (offsets[depth2])
+			break;
 
 	mutex_lock(&ufsi->truncate_mutex);
 	switch (depth) {
 	case 1:
 		ufs_trunc_direct(inode);
-		ufs_trunc_indirect(inode, NULL,
+		ufs_trunc_indirect(inode, NULL, 0,
 			   ufs_get_direct_data_ptr(uspi, ufsi, UFS_IND_BLOCK));
-		ufs_trunc_dindirect(inode, NULL,
+		ufs_trunc_dindirect(inode, NULL, 0,
 			    ufs_get_direct_data_ptr(uspi, ufsi, UFS_DIND_BLOCK));
-		ufs_trunc_tindirect(inode, NULL);
+		ufs_trunc_tindirect(inode, NULL, 0);
 		break;
 	case 2:
-		ufs_trunc_indirect(inode, offsets + 1,
+		ufs_trunc_indirect(inode, offsets + 1, depth2,
 			   ufs_get_direct_data_ptr(uspi, ufsi, UFS_IND_BLOCK));
-		ufs_trunc_dindirect(inode, NULL,
+		ufs_trunc_dindirect(inode, NULL, 0,
 			    ufs_get_direct_data_ptr(uspi, ufsi, UFS_DIND_BLOCK));
-		ufs_trunc_tindirect(inode, NULL);
+		ufs_trunc_tindirect(inode, NULL, 0);
 		break;
 	case 3:
-		ufs_trunc_dindirect(inode, offsets + 1,
+		ufs_trunc_dindirect(inode, offsets + 1, depth2,
 			    ufs_get_direct_data_ptr(uspi, ufsi, UFS_DIND_BLOCK));
-		ufs_trunc_tindirect(inode, NULL);
+		ufs_trunc_tindirect(inode, NULL, 0);
 		break;
 	case 4:
-		ufs_trunc_tindirect(inode, offsets + 1);
+		ufs_trunc_tindirect(inode, offsets + 1, depth2);
 	}
 	ufsi->i_lastfrag = DIRECT_FRAGMENT;
 	mutex_unlock(&ufsi->truncate_mutex);