Btrfs: pretend page cache & commit code

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

1 files changed, 89 insertions, 2 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c42dc72706bf..656ace6147a8 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -11,6 +11,8 @@
 #include "disk-io.h"
 
 static int allocated_blocks = 0;
+int cache_size = 0;
+int cache_max = 10000;
 
 static int check_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 {
@@ -21,6 +23,25 @@ static int check_tree_block(struct ctree_root *root, struct tree_buffer *buf)
         return 0;
 }
 
+static int free_some_buffers(struct ctree_root *root)
+{
+        struct list_head *node, *next;
+        struct tree_buffer *b;
+        if (root->cache_size < cache_max)
+                return 0;
+        list_for_each_safe(node, next, &root->cache) {
+                b = list_entry(node, struct tree_buffer, cache);
+                if (b->count == 1) {
+                        BUG_ON(!list_empty(&b->dirty));
+                        list_del_init(&b->cache);
+                        tree_block_release(root, b);
+                        if (root->cache_size < cache_max)
+                                return 0;
+                }
+        }
+        return 0;
+}
+
 struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
 {
         struct tree_buffer *buf;
@@ -30,10 +51,14 @@ struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
                 return buf;
         allocated_blocks++;
         buf->blocknr = blocknr;
-        buf->count = 1;
+        buf->count = 2;
+        INIT_LIST_HEAD(&buf->dirty);
+        free_some_buffers(root);
         radix_tree_preload(GFP_KERNEL);
         ret = radix_tree_insert(&root->cache_radix, blocknr, buf);
         radix_tree_preload_end();
+        list_add_tail(&buf->cache, &root->cache);
+        root->cache_size++;
         if (ret) {
                 free(buf);
                 return NULL;
@@ -57,7 +82,6 @@ struct tree_buffer *find_tree_block(struct ctree_root *root, u64 blocknr)
         return buf;
 }
 
-
 struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
 {
         loff_t offset = blocknr * CTREE_BLOCKSIZE;
@@ -82,6 +106,24 @@ struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
         return buf;
 }
 
+int dirty_tree_block(struct ctree_root *root, struct tree_buffer *buf)
+{
+        if (!list_empty(&buf->dirty))
+                return 0;
+        list_add_tail(&buf->dirty, &root->trans);
+        buf->count++;
+        return 0;
+}
+
+int clean_tree_block(struct ctree_root *root, struct tree_buffer *buf)
+{
+        if (!list_empty(&buf->dirty)) {
+                list_del_init(&buf->dirty);
+                tree_block_release(root, buf);
+        }
+        return 0;
+}
+
 int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 {
         u64 blocknr = buf->blocknr;
@@ -96,9 +138,37 @@ int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
         return 0;
 }
 
+static int __commit_transaction(struct ctree_root *root)
+{
+        struct tree_buffer *b;
+        int ret = 0;
+        int wret;
+        while(!list_empty(&root->trans)) {
+                b = list_entry(root->trans.next, struct tree_buffer, dirty);
+                list_del_init(&b->dirty);
+                wret = write_tree_block(root, b);
+                if (wret)
+                        ret = wret;
+                tree_block_release(root, b);
+        }
+        return ret;
+}
+
+int commit_transaction(struct ctree_root *root)
+{
+        int ret;
+        ret = __commit_transaction(root);
+        if (!ret && root != root->extent_root)
+                ret = __commit_transaction(root->extent_root);
+        BUG_ON(ret);
+        return ret;
+}
+
 static int __setup_root(struct ctree_root *root, struct ctree_root *extent_root,
                         struct ctree_root_info *info, int fp)
 {
+        INIT_LIST_HEAD(&root->trans);
+        INIT_LIST_HEAD(&root->cache);
         root->fp = fp;
         root->node = NULL;
         root->node = read_tree_block(root, info->tree_root);
@@ -157,8 +227,23 @@ int write_ctree_super(struct ctree_root *root, struct ctree_super_block *s)
         return 0;
 }
 
+static int drop_cache(struct ctree_root *root)
+{
+        while(!list_empty(&root->cache)) {
+                struct tree_buffer *b = list_entry(root->cache.next,
+                                                   struct tree_buffer, cache);
+                list_del_init(&b->cache);
+                tree_block_release(root, b);
+        }
+        return 0;
+}
 int close_ctree(struct ctree_root *root)
 {
+        drop_cache(root->extent_root);
+        drop_cache(root);
+        BUG_ON(!list_empty(&root->trans));
+        BUG_ON(!list_empty(&root->extent_root->trans));
+
         close(root->fp);
         if (root->node)
                 tree_block_release(root, root->node);
@@ -182,6 +267,8 @@ void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
                 free(buf);
                 BUG_ON(allocated_blocks == 0);
                 allocated_blocks--;
+                BUG_ON(root->cache_size == 0);
+                root->cache_size--;
         }
 }