Btrfs: groundwork for subvolume and snapshot roots

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

6 files changed, 282 insertions, 99 deletions

diff --git a/fs/btrfs/bit-radix.c b/fs/btrfs/bit-radix.c
index 783f54c2a16c..9fc42e99c7df 100644
--- a/fs/btrfs/bit-radix.c
+++ b/fs/btrfs/bit-radix.c
@@ -86,7 +86,7 @@ int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
         int i;
         int total_found = 0;
 
-        ret = radix_tree_gang_lookup(radix, (void *)&gang, 0, ARRAY_SIZE(gang));
+        ret = radix_tree_gang_lookup(radix, (void **)gang, 0, ARRAY_SIZE(gang));
         for (i = 0; i < ret && nr > 0; i++) {
                 found = 0;
                 bits = gang[i];
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1ff5b99af682..5460030c9e6a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -232,12 +232,12 @@ struct btrfs_inode_map_item {
 
 struct crypto_hash;
 struct btrfs_fs_info {
-        struct btrfs_root *fs_root;
         struct btrfs_root *extent_root;
         struct btrfs_root *tree_root;
         struct btrfs_root *inode_root;
         struct btrfs_key current_insert;
         struct btrfs_key last_insert;
+        struct radix_tree_root fs_roots_radix;
         struct radix_tree_root pending_del_radix;
         struct radix_tree_root pinned_radix;
         u64 last_inode_alloc;
@@ -266,6 +266,9 @@ struct btrfs_root {
         struct btrfs_root_item root_item;
         struct btrfs_key root_key;
         struct btrfs_fs_info *fs_info;
+        struct inode *inode;
+        u64 objectid;
+        u64 last_trans;
         u32 blocksize;
         int ref_cows;
         u32 type;
@@ -595,7 +598,7 @@ static inline u32 btrfs_key_overflow(struct btrfs_key *key)
 
 static inline void btrfs_set_key_overflow(struct btrfs_key *key, u32 over)
 {
-        BUG_ON(over > BTRFS_KEY_OVERFLOW_MAX);
+        BUG_ON(over >= BTRFS_KEY_OVERFLOW_MAX);
         over = over << BTRFS_KEY_OVERFLOW_SHIFT;
         key->flags = (key->flags & ~((u64)BTRFS_KEY_OVERFLOW_MASK)) | over;
 }
@@ -634,7 +637,7 @@ static inline void btrfs_set_disK_key_overflow(struct btrfs_disk_key *key,
                                                u32 over)
 {
         u32 flags = btrfs_disk_key_flags(key);
-        BUG_ON(over > BTRFS_KEY_OVERFLOW_MAX);
+        BUG_ON(over >= BTRFS_KEY_OVERFLOW_MAX);
         over = over << BTRFS_KEY_OVERFLOW_SHIFT;
         flags = (flags & ~((u64)BTRFS_KEY_OVERFLOW_MASK)) | over;
         btrfs_set_disk_key_flags(key, flags);
@@ -748,6 +751,17 @@ static inline void btrfs_set_super_blocknr(struct btrfs_super_block *s, u64 val)
         s->blocknr = cpu_to_le64(val);
 }
 
+static inline u64 btrfs_super_generation(struct btrfs_super_block *s)
+{
+        return le64_to_cpu(s->generation);
+}
+
+static inline void btrfs_set_super_generation(struct btrfs_super_block *s,
+                                              u64 val)
+{
+        s->generation = cpu_to_le64(val);
+}
+
 static inline u64 btrfs_super_root(struct btrfs_super_block *s)
 {
         return le64_to_cpu(s->root);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b9301a5e4608..b557bdd1e26a 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4,9 +4,11 @@
 #include <linux/crypto.h>
 #include <linux/scatterlist.h>
 #include <linux/swap.h>
+#include <linux/radix-tree.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
+#include "btrfs_inode.h"
 
 static int check_tree_block(struct btrfs_root *root, struct buffer_head *buf)
 {
@@ -180,7 +182,7 @@ static int csum_tree_block(struct btrfs_root *root, struct buffer_head *bh,
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
         struct buffer_head *bh;
-        struct btrfs_root *root = btrfs_sb(page->mapping->host->i_sb);
+        struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
         struct buffer_head *head;
         if (!page_has_buffers(page)) {
                 create_empty_buffers(page, root->fs_info->sb->s_blocksize,
@@ -259,10 +261,13 @@ static int __setup_root(int blocksize,
                         u64 objectid)
 {
         root->node = NULL;
+        root->inode = NULL;
         root->commit_root = NULL;
         root->blocksize = blocksize;
         root->ref_cows = 0;
         root->fs_info = fs_info;
+        root->objectid = objectid;
+        root->last_trans = 0;
         memset(&root->root_key, 0, sizeof(root->root_key));
         memset(&root->root_item, 0, sizeof(root->root_item));
         return 0;
@@ -287,10 +292,78 @@ static int find_and_setup_root(int blocksize,
         return 0;
 }
 
+struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
+                                      struct btrfs_key *location)
+{
+        struct btrfs_root *root;
+        struct btrfs_root *tree_root = fs_info->tree_root;
+        struct btrfs_path *path;
+        struct btrfs_leaf *l;
+        int ret = 0;
+
+printk("read_fs_root looking for %Lu %Lu %u\n", location->objectid, location->offset, location->flags);
+        root = kmalloc(sizeof(*root), GFP_NOFS);
+        if (!root) {
+printk("failed1\n");
+                return ERR_PTR(-ENOMEM);
+        }
+        if (location->offset == (u64)-1) {
+                ret = find_and_setup_root(fs_info->sb->s_blocksize,
+                                          fs_info->tree_root, fs_info,
+                                          location->objectid, root);
+                if (ret) {
+printk("failed2\n");
+                        kfree(root);
+                        return ERR_PTR(ret);
+                }
+                goto insert;
+        }
+
+        __setup_root(fs_info->sb->s_blocksize, root, fs_info,
+                     location->objectid);
+
+        path = btrfs_alloc_path();
+        BUG_ON(!path);
+        ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
+        if (ret != 0) {
+printk("internal search_slot gives us %d\n", ret);
+                if (ret > 0)
+                        ret = -ENOENT;
+                goto out;
+        }
+        l = btrfs_buffer_leaf(path->nodes[0]);
+        memcpy(&root->root_item,
+               btrfs_item_ptr(l, path->slots[0], struct btrfs_root_item),
+               sizeof(root->root_item));
+        memcpy(&root->root_key, location, sizeof(*location));
+        ret = 0;
+out:
+        btrfs_release_path(root, path);
+        btrfs_free_path(path);
+        if (ret) {
+                kfree(root);
+                return ERR_PTR(ret);
+        }
+        root->node = read_tree_block(root,
+                                     btrfs_root_blocknr(&root->root_item));
+        BUG_ON(!root->node);
+insert:
+printk("inserting %p\n", root);
+        root->ref_cows = 1;
+        ret = radix_tree_insert(&fs_info->fs_roots_radix, (unsigned long)root,
+                                root);
+        if (ret) {
+printk("radix_tree_insert gives us %d\n", ret);
+                brelse(root->node);
+                kfree(root);
+                return ERR_PTR(ret);
+        }
+printk("all worked\n");
+        return root;
+}
+
 struct btrfs_root *open_ctree(struct super_block *sb)
 {
-        struct btrfs_root *root = kmalloc(sizeof(struct btrfs_root),
-                                          GFP_NOFS);
         struct btrfs_root *extent_root = kmalloc(sizeof(struct btrfs_root),
                                                  GFP_NOFS);
         struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
@@ -304,9 +377,9 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 
         init_bit_radix(&fs_info->pinned_radix);
         init_bit_radix(&fs_info->pending_del_radix);
+        INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
         sb_set_blocksize(sb, 4096);
         fs_info->running_transaction = NULL;
-        fs_info->fs_root = root;
         fs_info->tree_root = tree_root;
         fs_info->extent_root = extent_root;
         fs_info->inode_root = inode_root;
@@ -318,6 +391,9 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         fs_info->btree_inode->i_nlink = 1;
         fs_info->btree_inode->i_size = sb->s_bdev->bd_inode->i_size;
         fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
+        BTRFS_I(fs_info->btree_inode)->root = tree_root;
+        memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
+               sizeof(struct btrfs_key));
         insert_inode_hash(fs_info->btree_inode);
         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
         fs_info->hash_tfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);
@@ -337,13 +413,12 @@ struct btrfs_root *open_ctree(struct super_block *sb)
                                              BTRFS_SUPER_INFO_OFFSET /
                                              sb->s_blocksize);
 
-        if (!fs_info->sb_buffer) {
+        if (!fs_info->sb_buffer)
                 return NULL;
-        }
         disk_super = (struct btrfs_super_block *)fs_info->sb_buffer->b_data;
-        if (!btrfs_super_root(disk_super)) {
+        if (!btrfs_super_root(disk_super))
                 return NULL;
-        }
+
         fs_info->disk_super = disk_super;
         tree_root->node = read_tree_block(tree_root,
                                           btrfs_super_root(disk_super));
@@ -358,14 +433,8 @@ struct btrfs_root *open_ctree(struct super_block *sb)
                                   BTRFS_INODE_MAP_OBJECTID, inode_root);
         BUG_ON(ret);
 
-        ret = find_and_setup_root(sb->s_blocksize, tree_root, fs_info,
-                                  BTRFS_FS_TREE_OBJECTID, root);
-        BUG_ON(ret);
-        root->commit_root = root->node;
-        get_bh(root->node);
-        root->ref_cows = 1;
-        root->fs_info->generation = root->root_key.offset + 1;
-        ret = btrfs_find_highest_inode(root, &root->fs_info->last_inode_alloc);
+        fs_info->generation = btrfs_super_generation(disk_super) + 1;
+        ret = btrfs_find_highest_inode(tree_root, &fs_info->last_inode_alloc);
         if (ret == 0)
                 fs_info->highest_inode = fs_info->last_inode_alloc;
         memset(&fs_info->kobj, 0, sizeof(fs_info->kobj));
@@ -373,7 +442,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         kobject_set_name(&fs_info->kobj, "%s", sb->s_id);
         kobject_register(&fs_info->kobj);
         mutex_unlock(&fs_info->fs_mutex);
-        return root;
+        return tree_root;
 }
 
 int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
@@ -398,12 +467,42 @@ int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
         return 0;
 }
 
+int del_fs_roots(struct btrfs_fs_info *fs_info)
+{
+        int ret;
+        struct btrfs_root *gang[8];
+        int i;
+
+        while(1) {
+                ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
+                                             (void **)gang, 0,
+                                             ARRAY_SIZE(gang));
+                if (!ret)
+                        break;
+                for (i = 0; i < ret; i++) {
+                        radix_tree_delete(&fs_info->fs_roots_radix,
+                                          (unsigned long)gang[i]);
+                        if (gang[i]->inode)
+                                iput(gang[i]->inode);
+                        else
+                                printk("no inode for root %p\n", gang[i]);
+                        if (gang[i]->node)
+                                brelse(gang[i]->node);
+                        if (gang[i]->commit_root)
+                                brelse(gang[i]->commit_root);
+                        kfree(gang[i]);
+                }
+        }
+        return 0;
+}
+
 int close_ctree(struct btrfs_root *root)
 {
         int ret;
         struct btrfs_trans_handle *trans;
+        struct btrfs_fs_info *fs_info = root->fs_info;
 
-        mutex_lock(&root->fs_info->fs_mutex);
+        mutex_lock(&fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
         btrfs_commit_transaction(trans, root);
         /* run commit again to  drop the original snapshot */
@@ -412,29 +511,26 @@ int close_ctree(struct btrfs_root *root)
         ret = btrfs_write_and_wait_transaction(NULL, root);
         BUG_ON(ret);
         write_ctree_super(NULL, root);
-        mutex_unlock(&root->fs_info->fs_mutex);
-
-        if (root->node)
-                btrfs_block_release(root, root->node);
-        if (root->fs_info->extent_root->node)
-                btrfs_block_release(root->fs_info->extent_root,
-                                    root->fs_info->extent_root->node);
-        if (root->fs_info->inode_root->node)
-                btrfs_block_release(root->fs_info->inode_root,
-                                    root->fs_info->inode_root->node);
-        if (root->fs_info->tree_root->node)
-                btrfs_block_release(root->fs_info->tree_root,
-                                    root->fs_info->tree_root->node);
-        btrfs_block_release(root, root->commit_root);
-        btrfs_block_release(root, root->fs_info->sb_buffer);
-        crypto_free_hash(root->fs_info->hash_tfm);
-        truncate_inode_pages(root->fs_info->btree_inode->i_mapping, 0);
-        iput(root->fs_info->btree_inode);
-        kfree(root->fs_info->extent_root);
-        kfree(root->fs_info->inode_root);
-        kfree(root->fs_info->tree_root);
-        kobject_unregister(&root->fs_info->kobj);
-        kfree(root);
+        mutex_unlock(&fs_info->fs_mutex);
+
+        if (fs_info->extent_root->node)
+                btrfs_block_release(fs_info->extent_root,
+                                    fs_info->extent_root->node);
+        if (fs_info->inode_root->node)
+                btrfs_block_release(fs_info->inode_root,
+                                    fs_info->inode_root->node);
+        if (fs_info->tree_root->node)
+                btrfs_block_release(fs_info->tree_root,
+                                    fs_info->tree_root->node);
+        btrfs_block_release(root, fs_info->sb_buffer);
+        crypto_free_hash(fs_info->hash_tfm);
+        truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
+        iput(fs_info->btree_inode);
+        del_fs_roots(fs_info);
+        kfree(fs_info->extent_root);
+        kfree(fs_info->inode_root);
+        kfree(fs_info->tree_root);
+        kobject_unregister(&fs_info->kobj);
         return 0;
 }
 
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index ac6764ba8aa6..0ef6e6f714af 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -39,4 +39,6 @@ int write_ctree_super(struct btrfs_trans_handle *trans,
 struct buffer_head *btrfs_find_tree_block(struct btrfs_root *root, u64 blocknr);
 int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
                     char *result);
+struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
+                                      struct btrfs_key *location);
 #endif
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 66d9fb2288c3..3c9236ca889c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -436,7 +436,6 @@ int fixup_tree_root_location(struct btrfs_root *root,
 {
         struct btrfs_path *path;
         struct btrfs_root_item *ri;
-        int ret;
 
         if (btrfs_key_type(location) != BTRFS_ROOT_ITEM_KEY)
                 return 0;
@@ -447,22 +446,19 @@ int fixup_tree_root_location(struct btrfs_root *root,
         BUG_ON(!path);
         mutex_lock(&root->fs_info->fs_mutex);
 
-        ret = btrfs_lookup_inode(NULL, root, path, location, 0);
-        if (ret)
-                goto out;
-        ri = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
-                          path->slots[0],
-                          struct btrfs_root_item);
+        *sub_root = btrfs_read_fs_root(root->fs_info, location);
+        if (IS_ERR(*sub_root))
+                return PTR_ERR(*sub_root);
+
+        ri = &(*sub_root)->root_item;
         location->objectid = btrfs_root_dirid(ri);
         location->flags = 0;
         btrfs_set_key_type(location, BTRFS_INODE_ITEM_KEY);
         location->offset = 0;
-        /* FIXME properly select the root */
-        *sub_root = root->fs_info->fs_root;
-out:
+
         btrfs_free_path(path);
         mutex_unlock(&root->fs_info->fs_mutex);
-        return ret;
+        return 0;
 }
 
 
@@ -494,6 +490,15 @@ static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
                 if (!inode)
                         return ERR_PTR(-EACCES);
                 if (inode->i_state & I_NEW) {
+                        if (sub_root != root) {
+                                ret = radix_tree_insert(
+                                                &root->fs_info->fs_roots_radix,
+                                                (unsigned long)sub_root,
+                                                sub_root);
+printk("adding new root for inode %lu\n", inode->i_ino);
+                                igrab(inode);
+                                sub_root->inode = inode;
+                        }
                         BTRFS_I(inode)->root = sub_root;
                         memcpy(&BTRFS_I(inode)->location, &location,
                                sizeof(location));
@@ -605,7 +610,7 @@ static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
         struct inode * inode;
         struct dentry * root_dentry;
         struct btrfs_super_block *disk_super;
-        struct btrfs_root *root;
+        struct btrfs_root *tree_root;
         struct btrfs_inode *bi;
 
         sb->s_maxbytes = MAX_LFS_FILESIZE;
@@ -613,14 +618,14 @@ static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
         sb->s_op = &btrfs_super_ops;
         sb->s_time_gran = 1;
 
-        root = open_ctree(sb);
+        tree_root = open_ctree(sb);
 
-        if (!root) {
+        if (!tree_root) {
                 printk("btrfs: open_ctree failed\n");
                 return -EIO;
         }
-        sb->s_fs_info = root;
-        disk_super = root->fs_info->disk_super;
+        sb->s_fs_info = tree_root;
+        disk_super = tree_root->fs_info->disk_super;
         printk("read in super total blocks %Lu root %Lu\n",
                btrfs_super_total_blocks(disk_super),
                btrfs_super_root_dir(disk_super));
@@ -630,7 +635,7 @@ static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
         bi->location.objectid = inode->i_ino;
         bi->location.offset = 0;
         bi->location.flags = 0;
-        bi->root = root->fs_info->tree_root;
+        bi->root = tree_root;
         btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);
 
         if (!inode)
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;
 }