Btrfs: groundwork for subvolume and snapshot roots

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

1 files changed, 103 insertions, 37 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 20d84bd03223..83a0194ab163 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -8,6 +8,8 @@ static int total_trans = 0;
 extern struct kmem_cache *btrfs_trans_handle_cachep;
 extern struct kmem_cache *btrfs_transaction_cachep;
 
+#define BTRFS_ROOT_TRANS_TAG 0
+
 #define TRANS_MAGIC 0xE1E10E
 static void put_transaction(struct btrfs_transaction *transaction)
 {
@@ -31,9 +33,10 @@ static int join_transaction(struct btrfs_root *root)
                                              GFP_NOFS);
                 total_trans++;
                 BUG_ON(!cur_trans);
+                root->fs_info->generation++;
                 root->fs_info->running_transaction = cur_trans;
                 cur_trans->num_writers = 0;
-                cur_trans->transid = root->root_key.offset + 1;
+                cur_trans->transid = root->fs_info->generation;
                 init_waitqueue_head(&cur_trans->writer_wait);
                 init_waitqueue_head(&cur_trans->commit_wait);
                 cur_trans->magic = TRANS_MAGIC;
@@ -51,13 +54,22 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
         struct btrfs_trans_handle *h =
                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
         int ret;
+        u64 running_trans_id;
 
-        /* FIXME, use the right root */
-        root = root->fs_info->fs_root;
         mutex_lock(&root->fs_info->trans_mutex);
         ret = join_transaction(root);
         BUG_ON(ret);
-        h->transid = root->fs_info->running_transaction->transid;
+        running_trans_id = root->fs_info->running_transaction->transid;
+
+        if (root != root->fs_info->tree_root && root->last_trans <
+            running_trans_id) {
+                radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+                                   (unsigned long)root, BTRFS_ROOT_TRANS_TAG);
+                root->commit_root = root->node;
+                get_bh(root->node);
+        }
+        root->last_trans = running_trans_id;
+        h->transid = running_trans_id;
         h->transaction = root->fs_info->running_transaction;
         h->blocks_reserved = num_blocks;
         h->blocks_used = 0;
@@ -72,9 +84,6 @@ int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 {
         struct btrfs_transaction *cur_trans;
 
-        /* FIXME, use the right root */
-        root = root->fs_info->fs_root;
-
         WARN_ON(trans->magic != TRANS_MAGIC);
         WARN_ON(trans->magic2 != TRANS_MAGIC);
         mutex_lock(&root->fs_info->trans_mutex);
@@ -145,17 +154,96 @@ static int wait_for_commit(struct btrfs_root *root,
         return 0;
 }
 
+struct dirty_root {
+        struct list_head list;
+        struct btrfs_key snap_key;
+        struct buffer_head *commit_root;
+        struct btrfs_root *root;
+};
+
+int add_dirty_roots(struct btrfs_trans_handle *trans,
+                    struct radix_tree_root *radix, struct list_head *list)
+{
+        struct dirty_root *dirty;
+        struct btrfs_root *gang[8];
+        struct btrfs_root *root;
+        int i;
+        int ret;
+        int err;
+printk("add dirty\n");
+        while(1) {
+                ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
+                                                 ARRAY_SIZE(gang),
+                                                 BTRFS_ROOT_TRANS_TAG);
+                if (ret == 0)
+                        break;
+                for (i = 0; i < ret; i++) {
+                        root = gang[i];
+                        radix_tree_tag_clear(radix, (unsigned long)root,
+                                             BTRFS_ROOT_TRANS_TAG);
+                        if (root->commit_root == root->node) {
+                                WARN_ON(root->node->b_blocknr !=
+                                        btrfs_root_blocknr(&root->root_item));
+                                brelse(root->commit_root);
+                                root->commit_root = NULL;
+                                continue;
+                        }
+                        dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+                        BUG_ON(!dirty);
+                        memcpy(&dirty->snap_key, &root->root_key,
+                               sizeof(root->root_key));
+                        dirty->commit_root = root->commit_root;
+                        root->commit_root = NULL;
+                        dirty->root = root;
+printk("adding dirty root %Lu gen %Lu blocknr %Lu\n", root->root_key.objectid, root->root_key.offset, dirty->commit_root->b_blocknr);
+                        root->root_key.offset = root->fs_info->generation;
+                        btrfs_set_root_blocknr(&root->root_item,
+                                               root->node->b_blocknr);
+                        err = btrfs_insert_root(trans, root->fs_info->tree_root,
+                                                &root->root_key,
+                                                &root->root_item);
+                        BUG_ON(err);
+                        list_add(&dirty->list, list);
+                }
+        }
+printk("add dirty done\n");
+        return 0;
+}
+
+int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list)
+{
+        struct dirty_root *dirty;
+        struct btrfs_trans_handle *trans;
+        int ret;
+
+        while(!list_empty(list)) {
+                dirty = list_entry(list->next, struct dirty_root, list);
+                list_del_init(&dirty->list);
+                trans = btrfs_start_transaction(tree_root, 1);
+printk("drop snapshot root %p, commit_root blocknr %Lu generation %Lu\n", dirty->root, dirty->commit_root->b_blocknr, dirty->snap_key.offset);
+                ret = btrfs_drop_snapshot(trans, dirty->root,
+                                          dirty->commit_root);
+                BUG_ON(ret);
+
+printk("del root objectid %Lu, offset %Lu\n", dirty->snap_key.objectid, dirty->snap_key.offset);
+                ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
+                BUG_ON(ret);
+                ret = btrfs_end_transaction(trans, tree_root);
+                BUG_ON(ret);
+                kfree(dirty);
+        }
+        return 0;
+}
+
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root)
 {
         int ret = 0;
-        struct buffer_head *snap;
-        struct btrfs_key snap_key;
         struct btrfs_transaction *cur_trans;
+        struct list_head dirty_fs_roots;
         DEFINE_WAIT(wait);
 
-        /* FIXME, use the right root */
-        root = root->fs_info->fs_root;
+        INIT_LIST_HEAD(&dirty_fs_roots);
 
         mutex_lock(&root->fs_info->trans_mutex);
         if (trans->transaction->in_commit) {
@@ -184,22 +272,13 @@ printk("already in commit!, waiting\n");
         }
         finish_wait(&trans->transaction->writer_wait, &wait);
         WARN_ON(cur_trans != trans->transaction);
-        if (root->node != root->commit_root) {
-                memcpy(&snap_key, &root->root_key, sizeof(snap_key));
-                root->root_key.offset++;
-        }
-
-        if (btrfs_root_blocknr(&root->root_item) != root->node->b_blocknr) {
-                btrfs_set_root_blocknr(&root->root_item, root->node->b_blocknr);
-                ret = btrfs_insert_root(trans, root->fs_info->tree_root,
-                                        &root->root_key, &root->root_item);
-                BUG_ON(ret);
-        }
-
+        add_dirty_roots(trans, &root->fs_info->fs_roots_radix, &dirty_fs_roots);
         ret = btrfs_commit_tree_roots(trans, root);
         BUG_ON(ret);
         cur_trans = root->fs_info->running_transaction;
         root->fs_info->running_transaction = NULL;
+        btrfs_set_super_generation(root->fs_info->disk_super,
+                                   root->fs_info->generation + 1);
         mutex_unlock(&root->fs_info->trans_mutex);
         ret = btrfs_write_and_wait_transaction(trans, root);
         BUG_ON(ret);
@@ -213,21 +292,8 @@ printk("already in commit!, waiting\n");
         put_transaction(cur_trans);
         mutex_unlock(&root->fs_info->trans_mutex);
         kmem_cache_free(btrfs_trans_handle_cachep, trans);
-        if (root->node != root->commit_root) {
-                trans = btrfs_start_transaction(root, 1);
-                snap = root->commit_root;
-                root->commit_root = root->node;
-                get_bh(root->node);
-                ret = btrfs_drop_snapshot(trans, root, snap);
-                BUG_ON(ret);
 
-                ret = btrfs_del_root(trans, root->fs_info->tree_root,
-                                     &snap_key);
-                BUG_ON(ret);
-                root->fs_info->generation = root->root_key.offset + 1;
-                ret = btrfs_end_transaction(trans, root);
-                BUG_ON(ret);
-        }
+        drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
         return ret;
 }