Btrfs: Change push_leaf_{leaf,right} to empty the src leave during item deletion

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 50 insertions, 24 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ea9b46699349..1b47fe71e0b4 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1394,19 +1394,21 @@ int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
  * room, 0 if everything worked out and < 0 if there were major errors.
  */
 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
-                           *root, struct btrfs_path *path, int data_size)
+                           *root, struct btrfs_path *path, int data_size,
+                           int empty)
 {
         struct extent_buffer *left = path->nodes[0];
         struct extent_buffer *right;
         struct extent_buffer *upper;
         struct btrfs_disk_key disk_key;
         int slot;
-        int i;
+        u32 i;
         int free_space;
         int push_space = 0;
         int push_items = 0;
         struct btrfs_item *item;
         u32 left_nritems;
+        u32 nr;
         u32 right_nritems;
         u32 data_end;
         u32 this_item_size;
@@ -1447,7 +1449,13 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
                 return 1;
         }
 
-        for (i = left_nritems - 1; i >= 1; i--) {
+        if (empty)
+                nr = 0;
+        else
+                nr = 1;
+
+        i = left_nritems - 1;
+        while (i >= nr) {
                 item = btrfs_item_nr(left, i);
 
                 if (path->slots[0] == i)
@@ -1466,6 +1474,9 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
                         break;
                 push_items++;
                 push_space += this_item_size + sizeof(*item);
+                if (i == 0)
+                        break;
+                i--;
         }
         if (left->map_token) {
                 unmap_extent_buffer(left, left->map_token, KM_USER1);
@@ -1477,11 +1488,12 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
                 return 1;
         }
 
-        if (push_items == left_nritems)
+        if (!empty && push_items == left_nritems)
                 WARN_ON(1);
 
         /* push left to right */
         right_nritems = btrfs_header_nritems(right);
+
         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
         push_space -= leaf_data_end(root, left);
 
@@ -1511,7 +1523,6 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
         right_nritems += push_items;
         btrfs_set_header_nritems(right, right_nritems);
         push_space = BTRFS_LEAF_DATA_SIZE(root);
-
         for (i = 0; i < right_nritems; i++) {
                 item = btrfs_item_nr(right, i);
                 if (!right->map_token) {
@@ -1532,7 +1543,8 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
         left_nritems -= push_items;
         btrfs_set_header_nritems(left, left_nritems);
 
-        btrfs_mark_buffer_dirty(left);
+        if (left_nritems)
+                btrfs_mark_buffer_dirty(left);
         btrfs_mark_buffer_dirty(right);
 
         btrfs_item_key(right, &disk_key, 0);
@@ -1555,7 +1567,8 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
  */
 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
-                          *root, struct btrfs_path *path, int data_size)
+                          *root, struct btrfs_path *path, int data_size,
+                          int empty)
 {
         struct btrfs_disk_key disk_key;
         struct extent_buffer *right = path->nodes[0];
@@ -1568,6 +1581,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
         struct btrfs_item *item;
         u32 old_left_nritems;
         u32 right_nritems;
+        u32 nr;
         int ret = 0;
         int wret;
         u32 this_item_size;
@@ -1607,7 +1621,12 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
                 return 1;
         }
 
-        for (i = 0; i < right_nritems - 1; i++) {
+        if (empty)
+                nr = right_nritems;
+        else
+                nr = right_nritems - 1;
+
+        for (i = 0; i < nr; i++) {
                 item = btrfs_item_nr(right, i);
                 if (!right->map_token) {
                         map_extent_buffer(right, (unsigned long)item,
@@ -1637,7 +1656,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
                 free_extent_buffer(left);
                 return 1;
         }
-        if (push_items == btrfs_header_nritems(right))
+        if (!empty && push_items == btrfs_header_nritems(right))
                 WARN_ON(1);
 
         /* push data from right to left */
@@ -1681,20 +1700,26 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
         }
 
         /* fixup right node */
-        push_space = btrfs_item_offset_nr(right, push_items - 1) -
-                                          leaf_data_end(root, right);
-        memmove_extent_buffer(right, btrfs_leaf_data(right) +
-                              BTRFS_LEAF_DATA_SIZE(root) - push_space,
-                              btrfs_leaf_data(right) +
-                              leaf_data_end(root, right), push_space);
-
-        memmove_extent_buffer(right, btrfs_item_nr_offset(0),
+        if (push_items > right_nritems) {
+                printk("push items %d nr %u\n", push_items, right_nritems);
+                WARN_ON(1);
+        }
+
+        if (push_items < right_nritems) {
+                push_space = btrfs_item_offset_nr(right, push_items - 1) -
+                                                  leaf_data_end(root, right);
+                memmove_extent_buffer(right, btrfs_leaf_data(right) +
+                                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
+                                      btrfs_leaf_data(right) +
+                                      leaf_data_end(root, right), push_space);
+
+                memmove_extent_buffer(right, btrfs_item_nr_offset(0),
                               btrfs_item_nr_offset(push_items),
                              (btrfs_header_nritems(right) - push_items) *
                              sizeof(struct btrfs_item));
 
-        right_nritems = btrfs_header_nritems(right) - push_items;
-        btrfs_set_header_nritems(right, right_nritems);
+        }
+        btrfs_set_header_nritems(right, right_nritems - push_items);
         push_space = BTRFS_LEAF_DATA_SIZE(root);
 
         for (i = 0; i < right_nritems; i++) {
@@ -1717,7 +1742,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
         }
 
         btrfs_mark_buffer_dirty(left);
-        btrfs_mark_buffer_dirty(right);
+        if (right_nritems)
+                btrfs_mark_buffer_dirty(right);
 
         btrfs_item_key(right, &disk_key, 0);
         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
@@ -1768,12 +1794,12 @@ static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
 
         /* first try to make some room by pushing left and right */
         if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
-                wret = push_leaf_right(trans, root, path, data_size);
+                wret = push_leaf_right(trans, root, path, data_size, 0);
                 if (wret < 0) {
                         return wret;
                 }
                 if (wret) {
-                        wret = push_leaf_left(trans, root, path, data_size);
+                        wret = push_leaf_left(trans, root, path, data_size, 0);
                         if (wret < 0)
                                 return wret;
                 }
@@ -2403,13 +2429,13 @@ int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         slot = path->slots[1];
                         extent_buffer_get(leaf);
 
-                        wret = push_leaf_right(trans, root, path, 1);
+                        wret = push_leaf_right(trans, root, path, 1, 1);
                         if (wret < 0 && wret != -ENOSPC)
                                 ret = wret;
 
                         if (path->nodes[0] == leaf &&
                             btrfs_header_nritems(leaf)) {
-                                wret = push_leaf_left(trans, root, path, 1);
+                                wret = push_leaf_left(trans, root, path, 1, 1);
                                 if (wret < 0 && wret != -ENOSPC)
                                         ret = wret;
                         }