[PATCH 3.16 001/158] reiserfs: fix corruption introduced by balance_leaf refactor

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Mahoney <jeffm@suse.com>

commit 27d0e5bc85f3341b9ba66f0c23627cf9d7538c9d upstream.

Commits f1f007c308e (reiserfs: balance_leaf refactor, pull out
balance_leaf_insert_left) and cf22df182bf (reiserfs: balance_leaf
refactor, pull out balance_leaf_paste_left) missed that the `body'
pointer was getting repositioned. Subsequent users of the pointer
would expect it to be repositioned, and as a result, parts of the
tree would get overwritten. The most common observed corruption
is indirect block pointers being overwritten.

Since the body value isn't actually used anymore in the called routines,
we can pass back the offset it should be shifted. We constify the body
and ih pointers in the balance_leaf as a mostly-free preventative measure.

Reported-and-tested-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/reiserfs/do_balan.c |  111 +++++++++++++++++++++++++++----------------------
 fs/reiserfs/lbalance.c |    5 +-
 fs/reiserfs/reiserfs.h |    9 ++-
 3 files changed, 71 insertions(+), 54 deletions(-)

--- a/fs/reiserfs/do_balan.c
+++ b/fs/reiserfs/do_balan.c
@@ -286,12 +286,14 @@ static int balance_leaf_when_delete(stru
 	return 0;
 }
 
-static void balance_leaf_insert_left(struct tree_balance *tb,
-				     struct item_head *ih, const char *body)
+static unsigned int balance_leaf_insert_left(struct tree_balance *tb,
+					     struct item_head *const ih,
+					     const char * const body)
 {
 	int ret;
 	struct buffer_info bi;
 	int n = B_NR_ITEMS(tb->L[0]);
+	unsigned body_shift_bytes = 0;
 
 	if (tb->item_pos == tb->lnum[0] - 1 && tb->lbytes != -1) {
 		/* part of new item falls into L[0] */
@@ -329,7 +331,7 @@ static void balance_leaf_insert_left(str
 
 		put_ih_item_len(ih, new_item_len);
 		if (tb->lbytes > tb->zeroes_num) {
-			body += (tb->lbytes - tb->zeroes_num);
+			body_shift_bytes = tb->lbytes - tb->zeroes_num;
 			tb->zeroes_num = 0;
 		} else
 			tb->zeroes_num -= tb->lbytes;
@@ -349,11 +351,12 @@ static void balance_leaf_insert_left(str
 		tb->insert_size[0] = 0;
 		tb->zeroes_num = 0;
 	}
+	return body_shift_bytes;
 }
 
 static void balance_leaf_paste_left_shift_dirent(struct tree_balance *tb,
-						 struct item_head *ih,
-						 const char *body)
+						 struct item_head * const ih,
+						 const char * const body)
 {
 	int n = B_NR_ITEMS(tb->L[0]);
 	struct buffer_info bi;
@@ -413,17 +416,18 @@ static void balance_leaf_paste_left_shif
 	tb->pos_in_item -= tb->lbytes;
 }
 
-static void balance_leaf_paste_left_shift(struct tree_balance *tb,
-					  struct item_head *ih,
-					  const char *body)
+static unsigned int balance_leaf_paste_left_shift(struct tree_balance *tb,
+						  struct item_head * const ih,
+						  const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	int n = B_NR_ITEMS(tb->L[0]);
 	struct buffer_info bi;
+	int body_shift_bytes = 0;
 
 	if (is_direntry_le_ih(item_head(tbS0, tb->item_pos))) {
 		balance_leaf_paste_left_shift_dirent(tb, ih, body);
-		return;
+		return 0;
 	}
 
 	RFALSE(tb->lbytes <= 0,
@@ -497,7 +501,7 @@ static void balance_leaf_paste_left_shif
 		 * insert_size[0]
 		 */
 		if (l_n > tb->zeroes_num) {
-			body += (l_n - tb->zeroes_num);
+			body_shift_bytes = l_n - tb->zeroes_num;
 			tb->zeroes_num = 0;
 		} else
 			tb->zeroes_num -= l_n;
@@ -526,13 +530,14 @@ static void balance_leaf_paste_left_shif
 		 */
 		leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
 	}
+	return body_shift_bytes;
 }
 
 
 /* appended item will be in L[0] in whole */
 static void balance_leaf_paste_left_whole(struct tree_balance *tb,
-					  struct item_head *ih,
-					  const char *body)
+					  struct item_head * const ih,
+					  const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	int n = B_NR_ITEMS(tb->L[0]);
@@ -584,39 +589,44 @@ static void balance_leaf_paste_left_whol
 	tb->zeroes_num = 0;
 }
 
-static void balance_leaf_paste_left(struct tree_balance *tb,
-				    struct item_head *ih, const char *body)
+static unsigned int balance_leaf_paste_left(struct tree_balance *tb,
+					    struct item_head * const ih,
+					    const char * const body)
 {
 	/* we must shift the part of the appended item */
 	if (tb->item_pos == tb->lnum[0] - 1 && tb->lbytes != -1)
-		balance_leaf_paste_left_shift(tb, ih, body);
+		return balance_leaf_paste_left_shift(tb, ih, body);
 	else
 		balance_leaf_paste_left_whole(tb, ih, body);
+	return 0;
 }
 
 /* Shift lnum[0] items from S[0] to the left neighbor L[0] */
-static void balance_leaf_left(struct tree_balance *tb, struct item_head *ih,
-			      const char *body, int flag)
+static unsigned int balance_leaf_left(struct tree_balance *tb,
+				      struct item_head * const ih,
+				      const char * const body, int flag)
 {
 	if (tb->lnum[0] <= 0)
-		return;
+		return 0;
 
 	/* new item or it part falls to L[0], shift it too */
 	if (tb->item_pos < tb->lnum[0]) {
 		BUG_ON(flag != M_INSERT && flag != M_PASTE);
 
 		if (flag == M_INSERT)
-			balance_leaf_insert_left(tb, ih, body);
+			return balance_leaf_insert_left(tb, ih, body);
 		else /* M_PASTE */
-			balance_leaf_paste_left(tb, ih, body);
+			return balance_leaf_paste_left(tb, ih, body);
 	} else
 		/* new item doesn't fall into L[0] */
 		leaf_shift_left(tb, tb->lnum[0], tb->lbytes);
+	return 0;
 }
 
 
 static void balance_leaf_insert_right(struct tree_balance *tb,
-				      struct item_head *ih, const char *body)
+				      struct item_head * const ih,
+				      const char * const body)
 {
 
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
@@ -704,7 +714,8 @@ static void balance_leaf_insert_right(st
 
 
 static void balance_leaf_paste_right_shift_dirent(struct tree_balance *tb,
-				     struct item_head *ih, const char *body)
+				     struct item_head * const ih,
+				     const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	struct buffer_info bi;
@@ -754,7 +765,8 @@ static void balance_leaf_paste_right_shi
 }
 
 static void balance_leaf_paste_right_shift(struct tree_balance *tb,
-				     struct item_head *ih, const char *body)
+				     struct item_head * const ih,
+				     const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	int n_shift, n_rem, r_zeroes_number, version;
@@ -831,7 +843,8 @@ static void balance_leaf_paste_right_shi
 }
 
 static void balance_leaf_paste_right_whole(struct tree_balance *tb,
-				     struct item_head *ih, const char *body)
+				     struct item_head * const ih,
+				     const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	int n = B_NR_ITEMS(tbS0);
@@ -874,7 +887,8 @@ static void balance_leaf_paste_right_who
 }
 
 static void balance_leaf_paste_right(struct tree_balance *tb,
-				     struct item_head *ih, const char *body)
+				     struct item_head * const ih,
+				     const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	int n = B_NR_ITEMS(tbS0);
@@ -896,8 +910,9 @@ static void balance_leaf_paste_right(str
 }
 
 /* shift rnum[0] items from S[0] to the right neighbor R[0] */
-static void balance_leaf_right(struct tree_balance *tb, struct item_head *ih,
-			       const char *body, int flag)
+static void balance_leaf_right(struct tree_balance *tb,
+			       struct item_head * const ih,
+			       const char * const body, int flag)
 {
 	if (tb->rnum[0] <= 0)
 		return;
@@ -911,8 +926,8 @@ static void balance_leaf_right(struct tr
 }
 
 static void balance_leaf_new_nodes_insert(struct tree_balance *tb,
-					  struct item_head *ih,
-					  const char *body,
+					  struct item_head * const ih,
+					  const char * const body,
 					  struct item_head *insert_key,
 					  struct buffer_head **insert_ptr,
 					  int i)
@@ -1003,8 +1018,8 @@ static void balance_leaf_new_nodes_inser
 
 /* we append to directory item */
 static void balance_leaf_new_nodes_paste_dirent(struct tree_balance *tb,
-					 struct item_head *ih,
-					 const char *body,
+					 struct item_head * const ih,
+					 const char * const body,
 					 struct item_head *insert_key,
 					 struct buffer_head **insert_ptr,
 					 int i)
@@ -1058,8 +1073,8 @@ static void balance_leaf_new_nodes_paste
 }
 
 static void balance_leaf_new_nodes_paste_shift(struct tree_balance *tb,
-					 struct item_head *ih,
-					 const char *body,
+					 struct item_head * const ih,
+					 const char * const body,
 					 struct item_head *insert_key,
 					 struct buffer_head **insert_ptr,
 					 int i)
@@ -1131,8 +1146,8 @@ static void balance_leaf_new_nodes_paste
 }
 
 static void balance_leaf_new_nodes_paste_whole(struct tree_balance *tb,
-					       struct item_head *ih,
-					       const char *body,
+					       struct item_head * const ih,
+					       const char * const body,
 					       struct item_head *insert_key,
 					       struct buffer_head **insert_ptr,
 					       int i)
@@ -1184,8 +1199,8 @@ static void balance_leaf_new_nodes_paste
 
 }
 static void balance_leaf_new_nodes_paste(struct tree_balance *tb,
-					 struct item_head *ih,
-					 const char *body,
+					 struct item_head * const ih,
+					 const char * const body,
 					 struct item_head *insert_key,
 					 struct buffer_head **insert_ptr,
 					 int i)
@@ -1214,8 +1229,8 @@ static void balance_leaf_new_nodes_paste
 
 /* Fill new nodes that appear in place of S[0] */
 static void balance_leaf_new_nodes(struct tree_balance *tb,
-				   struct item_head *ih,
-				   const char *body,
+				   struct item_head * const ih,
+				   const char * const body,
 				   struct item_head *insert_key,
 				   struct buffer_head **insert_ptr,
 				   int flag)
@@ -1254,8 +1269,8 @@ static void balance_leaf_new_nodes(struc
 }
 
 static void balance_leaf_finish_node_insert(struct tree_balance *tb,
-					    struct item_head *ih,
-					    const char *body)
+					    struct item_head * const ih,
+					    const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	struct buffer_info bi;
@@ -1271,8 +1286,8 @@ static void balance_leaf_finish_node_ins
 }
 
 static void balance_leaf_finish_node_paste_dirent(struct tree_balance *tb,
-						  struct item_head *ih,
-						  const char *body)
+						  struct item_head * const ih,
+						  const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	struct item_head *pasted = item_head(tbS0, tb->item_pos);
@@ -1305,8 +1320,8 @@ static void balance_leaf_finish_node_pas
 }
 
 static void balance_leaf_finish_node_paste(struct tree_balance *tb,
-					   struct item_head *ih,
-					   const char *body)
+					   struct item_head * const ih,
+					   const char * const body)
 {
 	struct buffer_head *tbS0 = PATH_PLAST_BUFFER(tb->tb_path);
 	struct buffer_info bi;
@@ -1349,8 +1364,8 @@ static void balance_leaf_finish_node_pas
  * of the affected item which remains in S
  */
 static void balance_leaf_finish_node(struct tree_balance *tb,
-				      struct item_head *ih,
-				      const char *body, int flag)
+				      struct item_head * const ih,
+				      const char * const body, int flag)
 {
 	/* if we must insert or append into buffer S[0] */
 	if (0 <= tb->item_pos && tb->item_pos < tb->s0num) {
@@ -1402,7 +1417,7 @@ static int balance_leaf(struct tree_bala
 	    && is_indirect_le_ih(item_head(tbS0, tb->item_pos)))
 		tb->pos_in_item *= UNFM_P_SIZE;
 
-	balance_leaf_left(tb, ih, body, flag);
+	body += balance_leaf_left(tb, ih, body, flag);
 
 	/* tb->lnum[0] > 0 */
 	/* Calculate new item position */
--- a/fs/reiserfs/lbalance.c
+++ b/fs/reiserfs/lbalance.c
@@ -899,8 +899,9 @@ void leaf_delete_items(struct buffer_inf
 
 /* insert item into the leaf node in position before */
 void leaf_insert_into_buf(struct buffer_info *bi, int before,
-			  struct item_head *inserted_item_ih,
-			  const char *inserted_item_body, int zeros_number)
+			  struct item_head * const inserted_item_ih,
+			  const char * const inserted_item_body,
+			  int zeros_number)
 {
 	struct buffer_head *bh = bi->bi_bh;
 	int nr, free_space;
--- a/fs/reiserfs/reiserfs.h
+++ b/fs/reiserfs/reiserfs.h
@@ -3216,11 +3216,12 @@ int leaf_shift_right(struct tree_balance
 void leaf_delete_items(struct buffer_info *cur_bi, int last_first, int first,
 		       int del_num, int del_bytes);
 void leaf_insert_into_buf(struct buffer_info *bi, int before,
-			  struct item_head *inserted_item_ih,
-			  const char *inserted_item_body, int zeros_number);
-void leaf_paste_in_buffer(struct buffer_info *bi, int pasted_item_num,
-			  int pos_in_item, int paste_size, const char *body,
+			  struct item_head * const inserted_item_ih,
+			  const char * const inserted_item_body,
 			  int zeros_number);
+void leaf_paste_in_buffer(struct buffer_info *bi, int pasted_item_num,
+			  int pos_in_item, int paste_size,
+			  const char * const body, int zeros_number);
 void leaf_cut_from_buffer(struct buffer_info *bi, int cut_item_num,
 			  int pos_in_item, int cut_size);
 void leaf_paste_entries(struct buffer_info *bi, int item_num, int before,