Btrfs: pretend page cache & commit code
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c42dc72..656ace6 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 @@
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 @@
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 @@
return buf;
}
-
struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
{
loff_t offset = blocknr * CTREE_BLOCKSIZE;
@@ -82,6 +106,24 @@
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 @@
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 @@
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 @@
free(buf);
BUG_ON(allocated_blocks == 0);
allocated_blocks--;
+ BUG_ON(root->cache_size == 0);
+ root->cache_size--;
}
}