Btrfs: mount ro and remount support

This patch adds mount ro and remount support. The main
changes in patch are: adding btrfs_remount and related
helper function; splitting the transaction related code
out of close_ctree into btrfs_commit_super; updating
allocator to properly handle read only block group.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 63 insertions, 20 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3b0e974a9e9c..c599f0ee997a 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1075,10 +1075,12 @@ struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
                 kfree(root);
                 return ERR_PTR(ret);
         }
-        ret = btrfs_find_dead_roots(fs_info->tree_root,
-                                    root->root_key.objectid, root);
-        BUG_ON(ret);
-
+        if (!(fs_info->sb->s_flags & MS_RDONLY)) {
+                ret = btrfs_find_dead_roots(fs_info->tree_root,
+                                            root->root_key.objectid, root);
+                BUG_ON(ret);
+                btrfs_orphan_cleanup(root);
+        }
         return root;
 }
 
@@ -1700,7 +1702,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 
         btrfs_read_block_groups(extent_root);
 
-        fs_info->generation = btrfs_super_generation(disk_super) + 1;
+        fs_info->generation = generation + 1;
+        fs_info->last_trans_committed = generation;
         fs_info->data_alloc_profile = (u64)-1;
         fs_info->metadata_alloc_profile = (u64)-1;
         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
@@ -1715,6 +1718,9 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         if (!fs_info->transaction_kthread)
                 goto fail_cleaner;
 
+        if (sb->s_flags & MS_RDONLY)
+                return tree_root;
+
         if (btrfs_super_log_root(disk_super) != 0) {
                 u32 blocksize;
                 u64 bytenr = btrfs_super_log_root(disk_super);
@@ -1735,7 +1741,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                 ret = btrfs_recover_log_trees(log_tree_root);
                 BUG_ON(ret);
         }
-        fs_info->last_trans_committed = btrfs_super_generation(disk_super);
 
         ret = btrfs_cleanup_reloc_trees(tree_root);
         BUG_ON(ret);
@@ -1955,28 +1960,69 @@ static int del_fs_roots(struct btrfs_fs_info *fs_info)
         return 0;
 }
 
-int close_ctree(struct btrfs_root *root)
+int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)
 {
+        u64 root_objectid = 0;
+        struct btrfs_root *gang[8];
+        int i;
         int ret;
-        struct btrfs_trans_handle *trans;
-        struct btrfs_fs_info *fs_info = root->fs_info;
 
-        fs_info->closing = 1;
-        smp_mb();
+        while (1) {
+                ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
+                                             (void **)gang, root_objectid,
+                                             ARRAY_SIZE(gang));
+                if (!ret)
+                        break;
+                for (i = 0; i < ret; i++) {
+                        root_objectid = gang[i]->root_key.objectid;
+                        ret = btrfs_find_dead_roots(fs_info->tree_root,
+                                                    root_objectid, gang[i]);
+                        BUG_ON(ret);
+                        btrfs_orphan_cleanup(gang[i]);
+                }
+                root_objectid++;
+        }
+        return 0;
+}
 
-        kthread_stop(root->fs_info->transaction_kthread);
-        kthread_stop(root->fs_info->cleaner_kthread);
+int btrfs_commit_super(struct btrfs_root *root)
+{
+        struct btrfs_trans_handle *trans;
+        int ret;
 
+        mutex_lock(&root->fs_info->cleaner_mutex);
         btrfs_clean_old_snapshots(root);
+        mutex_unlock(&root->fs_info->cleaner_mutex);
         trans = btrfs_start_transaction(root, 1);
         ret = btrfs_commit_transaction(trans, root);
-        /* run commit again to  drop the original snapshot */
+        BUG_ON(ret);
+        /* run commit again to drop the original snapshot */
         trans = btrfs_start_transaction(root, 1);
         btrfs_commit_transaction(trans, root);
         ret = btrfs_write_and_wait_transaction(NULL, root);
         BUG_ON(ret);
 
-        write_ctree_super(NULL, root);
+        ret = write_ctree_super(NULL, root);
+        return ret;
+}
+
+int close_ctree(struct btrfs_root *root)
+{
+        struct btrfs_fs_info *fs_info = root->fs_info;
+        int ret;
+
+        fs_info->closing = 1;
+        smp_mb();
+
+        kthread_stop(root->fs_info->transaction_kthread);
+        kthread_stop(root->fs_info->cleaner_kthread);
+
+        if (!(fs_info->sb->s_flags & MS_RDONLY)) {
+                ret =  btrfs_commit_super(root);
+                if (ret) {
+                        printk("btrfs: commit super returns %d\n", ret);
+                }
+        }
 
         if (fs_info->delalloc_bytes) {
                 printk("btrfs: at unmount delalloc count %Lu\n",
@@ -2000,12 +2046,10 @@ int close_ctree(struct btrfs_root *root)
                 free_extent_buffer(root->fs_info->dev_root->node);
 
         btrfs_free_block_groups(root->fs_info);
-        fs_info->closing = 2;
-        del_fs_roots(fs_info);
 
-        filemap_write_and_wait(fs_info->btree_inode->i_mapping);
+        del_fs_roots(fs_info);
 
-        truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
+        iput(fs_info->btree_inode);
 
         btrfs_stop_workers(&fs_info->fixup_workers);
         btrfs_stop_workers(&fs_info->delalloc_workers);
@@ -2014,7 +2058,6 @@ int close_ctree(struct btrfs_root *root)
         btrfs_stop_workers(&fs_info->endio_write_workers);
         btrfs_stop_workers(&fs_info->submit_workers);
 
-        iput(fs_info->btree_inode);
 #if 0
         while(!list_empty(&fs_info->hashers)) {
                 struct btrfs_hasher *hasher;