Btrfs: Add the ability to find and remove dead roots after a crash.

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

7 files changed, 164 insertions, 32 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 77071f273977..fb6fffb71dd0 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -122,12 +122,12 @@ struct btrfs_super_block {
         u8 fsid[16];    /* FS specific uuid */
         __le64 blocknr; /* this block number */
         __le64 magic;
-        __le32 blocksize;
         __le64 generation;
         __le64 root;
         __le64 total_blocks;
         __le64 blocks_used;
         __le64 root_dir_objectid;
+        __le32 blocksize;
 } __attribute__ ((__packed__));
 
 /*
@@ -226,10 +226,12 @@ struct btrfs_root_item {
         struct btrfs_inode_item inode;
         __le64 root_dirid;
         __le64 blocknr;
-        __le32 flags;
         __le64 block_limit;
         __le64 blocks_used;
+        __le32 flags;
         __le32 refs;
+        struct btrfs_disk_key drop_progress;
+        u8 drop_level;
 } __attribute__ ((__packed__));
 
 #define BTRFS_FILE_EXTENT_REG 0
@@ -800,6 +802,16 @@ static inline void btrfs_set_root_refs(struct btrfs_root_item *item, u32 val)
         item->refs = cpu_to_le32(val);
 }
 
+static inline u32 btrfs_root_flags(struct btrfs_root_item *item)
+{
+        return le32_to_cpu(item->flags);
+}
+
+static inline void btrfs_set_root_flags(struct btrfs_root_item *item, u32 val)
+{
+        item->flags = cpu_to_le32(val);
+}
+
 static inline u64 btrfs_super_blocknr(struct btrfs_super_block *s)
 {
         return le64_to_cpu(s->blocknr);
@@ -1076,6 +1088,7 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
                       *item);
 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid, struct
                          btrfs_root_item *item, struct btrfs_key *key);
+int btrfs_find_dead_roots(struct btrfs_root *root);
 /* dir-item.c */
 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
                           *root, const char *name, int name_len, u64 dir,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 865a284aa06c..d7615e1578cc 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -326,8 +326,8 @@ 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 *btrfs_read_fs_root_no_radix(struct btrfs_fs_info *fs_info,
+                                               struct btrfs_key *location)
 {
         struct btrfs_root *root;
         struct btrfs_root *tree_root = fs_info->tree_root;
@@ -336,11 +336,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
         u64 highest_inode;
         int ret = 0;
 
-        root = radix_tree_lookup(&fs_info->fs_roots_radix,
-                                 (unsigned long)location->objectid);
-        if (root)
-                return root;
-        root = kmalloc(sizeof(*root), GFP_NOFS);
+        root = kzalloc(sizeof(*root), GFP_NOFS);
         if (!root)
                 return ERR_PTR(-ENOMEM);
         if (location->offset == (u64)-1) {
@@ -383,6 +379,28 @@ out:
         BUG_ON(!root->node);
 insert:
         root->ref_cows = 1;
+        ret = btrfs_find_highest_inode(root, &highest_inode);
+        if (ret == 0) {
+                root->highest_inode = highest_inode;
+                root->last_inode_alloc = highest_inode;
+        }
+        return root;
+}
+
+struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
+                                      struct btrfs_key *location)
+{
+        struct btrfs_root *root;
+        int ret;
+
+        root = radix_tree_lookup(&fs_info->fs_roots_radix,
+                                 (unsigned long)location->objectid);
+        if (root)
+                return root;
+
+        root = btrfs_read_fs_root_no_radix(fs_info, location);
+        if (IS_ERR(root))
+                return root;
         ret = radix_tree_insert(&fs_info->fs_roots_radix,
                                 (unsigned long)root->root_key.objectid,
                                 root);
@@ -391,11 +409,6 @@ insert:
                 kfree(root);
                 return ERR_PTR(ret);
         }
-        ret = btrfs_find_highest_inode(root, &highest_inode);
-        if (ret == 0) {
-                root->highest_inode = highest_inode;
-                root->last_inode_alloc = highest_inode;
-        }
         return root;
 }
 
@@ -489,6 +502,9 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         btrfs_read_block_groups(extent_root);
 
         fs_info->generation = btrfs_super_generation(disk_super) + 1;
+        ret = btrfs_find_dead_roots(tree_root);
+        if (ret)
+                goto fail_tree_root;
         mutex_unlock(&fs_info->fs_mutex);
         return tree_root;
 
@@ -538,7 +554,7 @@ int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
         return 0;
 }
 
-static int free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
+int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
 {
         radix_tree_delete(&fs_info->fs_roots_radix,
                           (unsigned long)root->root_key.objectid);
@@ -565,7 +581,7 @@ static int del_fs_roots(struct btrfs_fs_info *fs_info)
                 if (!ret)
                         break;
                 for (i = 0; i < ret; i++)
-                        free_fs_root(fs_info, gang[i]);
+                        btrfs_free_fs_root(fs_info, gang[i]);
         }
         return 0;
 }
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 7b76ccc48754..c4a695ac44f6 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -65,6 +65,8 @@ 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);
+struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_fs_info *fs_info,
+                                               struct btrfs_key *location);
 u64 bh_blocknr(struct buffer_head *bh);
 int btrfs_insert_dev_radix(struct btrfs_root *root,
                            struct block_device *bdev,
@@ -75,4 +77,5 @@ int btrfs_map_bh_to_logical(struct btrfs_root *root, struct buffer_head *bh,
                              u64 logical);
 int btrfs_releasepage(struct page *page, gfp_t flags);
 void btrfs_btree_balance_dirty(struct btrfs_root *root);
+int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root);
 #endif
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 6d031daa7779..9d2a0a3f674d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2028,6 +2028,8 @@ static int create_subvol(struct btrfs_root *root, char *name, int namelen)
 
         btrfs_set_root_blocknr(&root_item, bh_blocknr(subvol));
         btrfs_set_root_refs(&root_item, 1);
+        memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
+        root_item.drop_level = 0;
         brelse(subvol);
         subvol = NULL;
 
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index ac0fae7780ff..737e5a38d17e 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -18,6 +18,7 @@
 
 #include <linux/module.h>
 #include "ctree.h"
+#include "transaction.h"
 #include "disk-io.h"
 #include "print-tree.h"
 
@@ -32,7 +33,7 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
 
         search_key.objectid = objectid;
         search_key.flags = (u32)-1;
-        search_key.offset = (u32)-1;
+        search_key.offset = (u64)-1;
 
         path = btrfs_alloc_path();
         BUG_ON(!path);
@@ -50,6 +51,7 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
         memcpy(item, btrfs_item_ptr(l, slot, struct btrfs_root_item),
                 sizeof(*item));
         btrfs_disk_key_to_cpu(key, &l->items[slot].key);
+printk("find last finds key %Lu %u %Lu slot %d search for obj %Lu\n", key->objectid, key->flags, key->offset, slot, objectid);
         ret = 0;
 out:
         btrfs_release_path(root, path);
@@ -93,6 +95,67 @@ int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
         return ret;
 }
 
+int btrfs_find_dead_roots(struct btrfs_root *root)
+{
+        struct btrfs_root *dead_root;
+        struct btrfs_item *item;
+        struct btrfs_root_item *ri;
+        struct btrfs_key key;
+        struct btrfs_path *path;
+        int ret;
+        u32 nritems;
+        struct btrfs_leaf *leaf;
+        int slot;
+
+        key.objectid = 0;
+        key.flags = 0;
+        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+        key.offset = 0;
+        path = btrfs_alloc_path();
+        if (!path)
+                return -ENOMEM;
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        if (ret < 0)
+                goto err;
+        while(1) {
+                leaf = btrfs_buffer_leaf(path->nodes[0]);
+                nritems = btrfs_header_nritems(&leaf->header);
+                slot = path->slots[0];
+                if (slot >= nritems) {
+                        ret = btrfs_next_leaf(root, path);
+                        if (ret)
+                                break;
+                        leaf = btrfs_buffer_leaf(path->nodes[0]);
+                        nritems = btrfs_header_nritems(&leaf->header);
+                        slot = path->slots[0];
+                }
+                item = leaf->items + slot;
+                btrfs_disk_key_to_cpu(&key, &item->key);
+                if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
+                        goto next;
+                ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
+                if (btrfs_root_refs(ri) != 0)
+                        goto next;
+                dead_root = btrfs_read_fs_root_no_radix(root->fs_info, &key);
+                if (IS_ERR(root)) {
+                        ret = PTR_ERR(root);
+                        goto err;
+                }
+printk("found dead root %Lu %u %Lu\n", key.objectid, key.flags, key.offset);
+                ret = btrfs_add_dead_root(dead_root,
+                                          &root->fs_info->dead_roots);
+                if (ret)
+                        goto err;
+next:
+                slot++;
+                path->slots[0]++;
+        }
+        ret = 0;
+err:
+        btrfs_free_path(path);
+        return ret;
+}
+
 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                    struct btrfs_key *key)
 {
@@ -111,14 +174,8 @@ int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                             path->slots[0], struct btrfs_root_item);
 
         refs = btrfs_root_refs(ri);
-        BUG_ON(refs == 0);
-        if (refs == 1) {
-                ret = btrfs_del_item(trans, root, path);
-        } else {
-                btrfs_set_root_refs(ri, refs - 1);
-                WARN_ON(1);
-                mark_buffer_dirty(path->nodes[0]);
-        }
+        BUG_ON(refs != 0);
+        ret = btrfs_del_item(trans, root, path);
 out:
         btrfs_release_path(root, path);
         btrfs_free_path(path);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 321f8852755b..85a2a5e27148 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -85,11 +85,15 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 
         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->root_key.objectid,
-                                   BTRFS_ROOT_TRANS_TAG);
-                root->commit_root = root->node;
-                get_bh(root->node);
+                if (root->root_item.refs != 0) {
+                        radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+                                           (unsigned long)root->root_key.objectid,
+                                           BTRFS_ROOT_TRANS_TAG);
+                        root->commit_root = root->node;
+                        get_bh(root->node);
+                } else {
+                        WARN_ON(1);
+                }
         }
         root->last_trans = running_trans_id;
         h->transid = running_trans_id;
@@ -208,8 +212,24 @@ struct dirty_root {
         struct btrfs_key snap_key;
         struct buffer_head *commit_root;
         struct btrfs_root *root;
+        int free_on_drop;
 };
 
+int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list)
+{
+        struct dirty_root *dirty;
+
+        dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+        if (!dirty)
+                return -ENOMEM;
+        memcpy(&dirty->snap_key, &root->root_key, sizeof(root->root_key));
+        dirty->commit_root = root->node;
+        dirty->root = root;
+        dirty->free_on_drop = 1;
+        list_add(&dirty->list, dead_list);
+        return 0;
+}
+
 static int add_dirty_roots(struct btrfs_trans_handle *trans,
                            struct radix_tree_root *radix,
                            struct list_head *list)
@@ -217,9 +237,11 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
         struct dirty_root *dirty;
         struct btrfs_root *gang[8];
         struct btrfs_root *root;
+        struct btrfs_root_item tmp_item;
         int i;
         int ret;
         int err = 0;
+        u32 refs;
 
         while(1) {
                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
@@ -246,6 +268,9 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
                         dirty->commit_root = root->commit_root;
                         root->commit_root = NULL;
                         dirty->root = root;
+                        dirty->free_on_drop = 0;
+                        memcpy(&tmp_item, &root->root_item, sizeof(tmp_item));
+
                         root->root_key.offset = root->fs_info->generation;
                         btrfs_set_root_blocknr(&root->root_item,
                                                bh_blocknr(root->node));
@@ -254,7 +279,18 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
                                                 &root->root_item);
                         if (err)
                                 break;
-                        list_add(&dirty->list, list);
+
+                        refs = btrfs_root_refs(&tmp_item);
+                        btrfs_set_root_refs(&tmp_item, refs - 1);
+                        err = btrfs_update_root(trans, root->fs_info->tree_root,
+                                                &dirty->snap_key,
+                                                &tmp_item);
+
+                        BUG_ON(err);
+                        if (refs == 1)
+                                list_add(&dirty->list, list);
+                        else
+                                kfree(dirty);
                 }
         }
         return err;
@@ -270,16 +306,20 @@ static int drop_dirty_roots(struct btrfs_root *tree_root,
                 mutex_lock(&tree_root->fs_info->fs_mutex);
                 dirty = list_entry(list->next, struct dirty_root, list);
                 list_del_init(&dirty->list);
+
                 trans = btrfs_start_transaction(tree_root, 1);
+printk("deleting root %Lu %u %Lu\n", dirty->snap_key.objectid, dirty->snap_key.flags, dirty->snap_key.offset);
                 ret = btrfs_drop_snapshot(trans, dirty->root,
                                           dirty->commit_root);
                 BUG_ON(ret);
-
                 ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
                 if (ret)
                         break;
                 ret = btrfs_end_transaction(trans, tree_root);
                 BUG_ON(ret);
+
+                if (dirty->free_on_drop)
+                        kfree(dirty->root);
                 kfree(dirty);
                 mutex_unlock(&tree_root->fs_info->fs_mutex);
                 btrfs_btree_balance_dirty(tree_root);
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 5fb1d322aa10..ebf44f3e1118 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -69,5 +69,6 @@ void btrfs_transaction_flush_work(struct btrfs_root *root);
 void btrfs_transaction_queue_work(struct btrfs_root *root, int delay);
 void btrfs_init_transaction_sys(void);
 void btrfs_exit_transaction_sys(void);
+int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list);
 
 #endif