Btrfs: Run igrab on data=ordered inodes to prevent deadlocks during writeout

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

5 files changed, 37 insertions, 10 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1e19f2d86334..fa65fe027e45 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1145,7 +1145,7 @@ int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
 int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 int btrfs_readpage(struct file *file, struct page *page);
 void btrfs_delete_inode(struct inode *inode);
-void btrfs_drop_inode(struct inode *inode);
+void btrfs_put_inode(struct inode *inode);
 void btrfs_read_locked_inode(struct inode *inode);
 int btrfs_write_inode(struct inode *inode, int wait);
 void btrfs_dirty_inode(struct inode *inode);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f83f88ca8ac7..c1ac0bcbb462 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -601,6 +601,7 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
 {
         struct btrfs_root *root;
         struct btrfs_trans_handle *trans;
+        struct inode *inode = dentry->d_inode;
         int ret;
         unsigned long nr = 0;
 
@@ -617,6 +618,18 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
         ret = btrfs_unlink_trans(trans, root, dir, dentry);
         nr = trans->blocks_used;
 
+        if (inode->i_nlink == 0) {
+                int found;
+                /* if the inode isn't linked anywhere,
+                 * we don't need to worry about
+                 * data=ordered
+                 */
+                found = btrfs_del_ordered_inode(inode);
+                if (found == 1) {
+                        atomic_dec(&inode->i_count);
+                }
+        }
+
         btrfs_end_transaction(trans, root);
 fail:
         mutex_unlock(&root->fs_info->fs_mutex);
@@ -993,15 +1006,22 @@ fail:
         return err;
 }
 
-void btrfs_drop_inode(struct inode *inode)
+void btrfs_put_inode(struct inode *inode)
 {
-        if (!BTRFS_I(inode)->ordered_trans || inode->i_nlink) {
-                generic_drop_inode(inode);
+        int ret;
+
+        if (!BTRFS_I(inode)->ordered_trans) {
+                return;
+        }
+
+        if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY) ||
+            mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
                 return;
+
+        ret = btrfs_del_ordered_inode(inode);
+        if (ret == 1) {
+                atomic_dec(&inode->i_count);
         }
-        /* FIXME, make sure this delete actually ends up in the transaction */
-        btrfs_del_ordered_inode(inode);
-        generic_drop_inode(inode);
 }
 
 void btrfs_delete_inode(struct inode *inode)
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index b56011baa17c..cba2b623d02e 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -153,6 +153,8 @@ int btrfs_add_ordered_inode(struct inode *inode)
         write_unlock(&tree->lock);
         if (node)
                 kfree(entry);
+        else
+                igrab(inode);
         return 0;
 }
 
@@ -221,6 +223,7 @@ int btrfs_find_del_first_ordered_inode(struct btrfs_ordered_inode_tree *tree,
 }
 
 static int __btrfs_del_ordered_inode(struct btrfs_ordered_inode_tree *tree,
+                                     struct inode *inode,
                                      u64 root_objectid, u64 objectid)
 {
         struct tree_entry *entry;
@@ -234,6 +237,7 @@ static int __btrfs_del_ordered_inode(struct btrfs_ordered_inode_tree *tree,
                 return 0;
         }
         rb_erase(node, &tree->tree);
+        BTRFS_I(inode)->ordered_trans = 0;
         write_unlock(&tree->lock);
         entry = rb_entry(node, struct tree_entry, rb_node);
         kfree(entry);
@@ -244,14 +248,16 @@ int btrfs_del_ordered_inode(struct inode *inode)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
         u64 root_objectid = root->root_key.objectid;
+        int ret = 0;
 
         spin_lock(&root->fs_info->new_trans_lock);
         if (root->fs_info->running_transaction) {
                 struct btrfs_ordered_inode_tree *tree;
                 tree = &root->fs_info->running_transaction->ordered_inode_tree;
-                __btrfs_del_ordered_inode(tree, root_objectid, inode->i_ino);
+                ret = __btrfs_del_ordered_inode(tree, inode, root_objectid,
+                                                inode->i_ino);
         }
         spin_unlock(&root->fs_info->new_trans_lock);
-        return 0;
+        return ret;
 }
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 4deea393ca94..e506de3168bc 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -425,7 +425,7 @@ static struct file_system_type btrfs_fs_type = {
 
 static struct super_operations btrfs_super_ops = {
         .delete_inode   = btrfs_delete_inode,
-        .drop_inode     = btrfs_drop_inode,
+        .put_inode      = btrfs_put_inode,
         .put_super      = btrfs_put_super,
         .read_inode     = btrfs_read_locked_inode,
         .write_super    = btrfs_write_super,
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index a3205808ab2b..08f7a188dc3e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -521,6 +521,7 @@ int btrfs_write_ordered_inodes(struct btrfs_trans_handle *trans,
                 if (inode) {
                         if (S_ISREG(inode->i_mode))
                                 filemap_write_and_wait(inode->i_mapping);
+                        atomic_dec(&inode->i_count);
                         iput(inode);
                 }
                 mutex_lock(&root->fs_info->fs_mutex);