Btrfs: dynamic allocation of path struct

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

1 files changed, 61 insertions, 39 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 37b87e28a2f3..d785b721b461 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -15,7 +15,7 @@ static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
                          *root, u64 blocknr, u64 num_blocks)
 {
-        struct btrfs_path path;
+        struct btrfs_path *path;
         int ret;
         struct btrfs_key key;
         struct btrfs_leaf *l;
@@ -25,23 +25,26 @@ static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
 
         find_free_extent(trans, root->fs_info->extent_root, 0, 0, (u64)-1,
                          &ins);
-        btrfs_init_path(&path);
+        path = btrfs_alloc_path();
+        BUG_ON(!path);
+        btrfs_init_path(path);
         key.objectid = blocknr;
         key.flags = 0;
         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
         key.offset = num_blocks;
-        ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
+        ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
                                 0, 1);
         if (ret != 0)
                 BUG();
         BUG_ON(ret != 0);
-        l = btrfs_buffer_leaf(path.nodes[0]);
-        item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
+        l = btrfs_buffer_leaf(path->nodes[0]);
+        item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
         refs = btrfs_extent_refs(item);
         btrfs_set_extent_refs(item, refs + 1);
-        btrfs_mark_buffer_dirty(path.nodes[0]);
+        btrfs_mark_buffer_dirty(path->nodes[0]);
 
-        btrfs_release_path(root->fs_info->extent_root, &path);
+        btrfs_release_path(root->fs_info->extent_root, path);
+        btrfs_free_path(path);
         finish_current_insert(trans, root->fs_info->extent_root);
         del_pending_extents(trans, root->fs_info->extent_root);
         return 0;
@@ -50,24 +53,27 @@ static int inc_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
 static int lookup_block_ref(struct btrfs_trans_handle *trans, struct btrfs_root
                             *root, u64 blocknr, u64 num_blocks, u32 *refs)
 {
-        struct btrfs_path path;
+        struct btrfs_path *path;
         int ret;
         struct btrfs_key key;
         struct btrfs_leaf *l;
         struct btrfs_extent_item *item;
-        btrfs_init_path(&path);
+
+        path = btrfs_alloc_path();
+        btrfs_init_path(path);
         key.objectid = blocknr;
         key.offset = num_blocks;
         key.flags = 0;
         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-        ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, &path,
+        ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
                                 0, 0);
         if (ret != 0)
                 BUG();
-        l = btrfs_buffer_leaf(path.nodes[0]);
-        item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
+        l = btrfs_buffer_leaf(path->nodes[0]);
+        item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
         *refs = btrfs_extent_refs(item);
-        btrfs_release_path(root->fs_info->extent_root, &path);
+        btrfs_release_path(root->fs_info->extent_root, path);
+        btrfs_free_path(path);
         return 0;
 }
 
@@ -200,7 +206,7 @@ static int pin_down_block(struct btrfs_root *root, u64 blocknr, int pending)
 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                          *root, u64 blocknr, u64 num_blocks, int pin)
 {
-        struct btrfs_path path;
+        struct btrfs_path *path;
         struct btrfs_key key;
         struct btrfs_fs_info *info = root->fs_info;
         struct btrfs_root *extent_root = info->extent_root;
@@ -215,20 +221,22 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
         key.offset = num_blocks;
 
         find_free_extent(trans, root, 0, 0, (u64)-1, &ins);
-        btrfs_init_path(&path);
-        ret = btrfs_search_slot(trans, extent_root, &key, &path, -1, 1);
+        path = btrfs_alloc_path();
+        BUG_ON(!path);
+        btrfs_init_path(path);
+        ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
         if (ret) {
                 printk("failed to find %Lu\n", key.objectid);
                 btrfs_print_tree(extent_root, extent_root->node);
                 printk("failed to find %Lu\n", key.objectid);
                 BUG();
         }
-        ei = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+        ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                             struct btrfs_extent_item);
         BUG_ON(ei->refs == 0);
         refs = btrfs_extent_refs(ei) - 1;
         btrfs_set_extent_refs(ei, refs);
-        btrfs_mark_buffer_dirty(path.nodes[0]);
+        btrfs_mark_buffer_dirty(path->nodes[0]);
         if (refs == 0) {
                 u64 super_blocks_used;
 
@@ -240,13 +248,14 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                 super_blocks_used = btrfs_super_blocks_used(info->disk_super);
                 btrfs_set_super_blocks_used(info->disk_super,
                                             super_blocks_used - num_blocks);
-                ret = btrfs_del_item(trans, extent_root, &path);
+                ret = btrfs_del_item(trans, extent_root, path);
                 if (extent_root->fs_info->last_insert.objectid > blocknr)
                         extent_root->fs_info->last_insert.objectid = blocknr;
                 if (ret)
                         BUG();
         }
-        btrfs_release_path(extent_root, &path);
+        btrfs_release_path(extent_root, path);
+        btrfs_free_path(path);
         finish_current_insert(trans, extent_root);
         return ret;
 }
@@ -319,7 +328,7 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                             *orig_root, u64 num_blocks, u64 search_start, u64
                             search_end, struct btrfs_key *ins)
 {
-        struct btrfs_path path;
+        struct btrfs_path *path;
         struct btrfs_key key;
         int ret;
         u64 hole_size = 0;
@@ -339,24 +348,25 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 
         ins->flags = 0;
         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
+        path = btrfs_alloc_path();
 
 check_failed:
-        btrfs_init_path(&path);
+        btrfs_init_path(path);
         ins->objectid = search_start;
         ins->offset = 0;
         start_found = 0;
-        ret = btrfs_search_slot(trans, root, ins, &path, 0, 0);
+        ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
         if (ret < 0)
                 goto error;
 
-        if (path.slots[0] > 0)
-                path.slots[0]--;
+        if (path->slots[0] > 0)
+                path->slots[0]--;
 
         while (1) {
-                l = btrfs_buffer_leaf(path.nodes[0]);
-                slot = path.slots[0];
+                l = btrfs_buffer_leaf(path->nodes[0]);
+                slot = path->slots[0];
                 if (slot >= btrfs_header_nritems(&l->header)) {
-                        ret = btrfs_next_leaf(root, &path);
+                        ret = btrfs_next_leaf(root, path);
                         if (ret == 0)
                                 continue;
                         if (ret < 0)
@@ -387,14 +397,14 @@ check_failed:
                 }
                 start_found = 1;
                 last_block = key.objectid + key.offset;
-                path.slots[0]++;
+                path->slots[0]++;
         }
         // FIXME -ENOSPC
 check_pending:
         /* we have to make sure we didn't find an extent that has already
          * been allocated by the map tree or the original allocation
          */
-        btrfs_release_path(root, &path);
+        btrfs_release_path(root, path);
         BUG_ON(ins->objectid < search_start);
         for (test_block = ins->objectid;
              test_block < ins->objectid + total_needed; test_block++) {
@@ -410,9 +420,11 @@ check_pending:
         root->fs_info->current_insert.flags = 0;
         root->fs_info->last_insert.objectid = ins->objectid;
         ins->offset = num_blocks;
+        btrfs_free_path(path);
         return 0;
 error:
-        btrfs_release_path(root, &path);
+        btrfs_release_path(root, path);
+        btrfs_free_path(path);
         return ret;
 }
 
@@ -533,6 +545,8 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
         int ret;
         u32 refs;
 
+        WARN_ON(*level < 0);
+        WARN_ON(*level >= BTRFS_MAX_LEVEL);
         ret = lookup_block_ref(trans, root, path->nodes[*level]->b_blocknr,
                                1, &refs);
         BUG_ON(ret);
@@ -542,6 +556,8 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
          * walk down to the last node level and free all the leaves
          */
         while(*level >= 0) {
+                WARN_ON(*level < 0);
+                WARN_ON(*level >= BTRFS_MAX_LEVEL);
                 cur = path->nodes[*level];
                 if (btrfs_header_level(btrfs_buffer_header(cur)) != *level)
                         WARN_ON(1);
@@ -564,6 +580,7 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
                         continue;
                 }
                 next = read_tree_block(root, blocknr);
+                WARN_ON(*level <= 0);
                 if (path->nodes[*level-1])
                         btrfs_block_release(root, path->nodes[*level-1]);
                 path->nodes[*level-1] = next;
@@ -571,6 +588,8 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
                 path->slots[*level] = 0;
         }
 out:
+        WARN_ON(*level < 0);
+        WARN_ON(*level >= BTRFS_MAX_LEVEL);
         ret = btrfs_free_extent(trans, root,
                                 path->nodes[*level]->b_blocknr, 1, 1);
         btrfs_block_release(root, path->nodes[*level]);
@@ -622,33 +641,36 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
         int ret = 0;
         int wret;
         int level;
-        struct btrfs_path path;
+        struct btrfs_path *path;
         int i;
         int orig_level;
 
-        btrfs_init_path(&path);
+        path = btrfs_alloc_path();
+        BUG_ON(!path);
+        btrfs_init_path(path);
 
         level = btrfs_header_level(btrfs_buffer_header(snap));
         orig_level = level;
-        path.nodes[level] = snap;
-        path.slots[level] = 0;
+        path->nodes[level] = snap;
+        path->slots[level] = 0;
         while(1) {
-                wret = walk_down_tree(trans, root, &path, &level);
+                wret = walk_down_tree(trans, root, path, &level);
                 if (wret > 0)
                         break;
                 if (wret < 0)
                         ret = wret;
 
-                wret = walk_up_tree(trans, root, &path, &level);
+                wret = walk_up_tree(trans, root, path, &level);
                 if (wret > 0)
                         break;
                 if (wret < 0)
                         ret = wret;
         }
         for (i = 0; i <= orig_level; i++) {
-                if (path.nodes[i]) {
-                        btrfs_block_release(root, path.nodes[i]);
+                if (path->nodes[i]) {
+                        btrfs_block_release(root, path->nodes[i]);
                 }
         }
+        btrfs_free_path(path);
         return ret;
 }