[PATCH 9/9] Unionfs: move debugging checks inside locks

[Erez Zadok]

This is to ensure that the objects we want to check aren't being destroyed
or changed by another thread.

Signed-off-by: Erez Zadok <ezk@xxxxxxxxxxxxx>
---
 fs/unionfs/commonfops.c |    7 ++++---
 fs/unionfs/dentry.c     |    2 +-
 fs/unionfs/file.c       |   10 +++++-----
 fs/unionfs/inode.c      |   25 +++++++++++++------------
 fs/unionfs/mmap.c       |    2 +-
 fs/unionfs/super.c      |    4 ++--
 fs/unionfs/xattr.c      |    8 ++++----
 7 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/fs/unionfs/commonfops.c b/fs/unionfs/commonfops.c
index 624f920..b33917e 100644
--- a/fs/unionfs/commonfops.c
+++ b/fs/unionfs/commonfops.c
@@ -573,6 +573,7 @@ int unionfs_open(struct inode *inode, struct file *file)
 		}
 	}
 
+	/* XXX: should this unlock be moved to the function bottom? */
 	unionfs_unlock_dentry(dentry);
 
 out:
@@ -582,12 +583,12 @@ out:
 		kfree(UNIONFS_F(file));
 	}
 out_nofree:
-	unionfs_read_unlock(inode->i_sb);
 	unionfs_check_inode(inode);
 	if (!err) {
 		unionfs_check_file(file);
 		unionfs_check_dentry(file->f_path.dentry->d_parent);
 	}
+	unionfs_read_unlock(inode->i_sb);
 	return err;
 }
 
@@ -786,8 +787,8 @@ long unionfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	}
 
 out:
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;
 }
 
@@ -825,7 +826,7 @@ int unionfs_flush(struct file *file, fl_owner_t id)
 	unionfs_copy_attr_times(dentry->d_parent->d_inode);
 
 out:
-	unionfs_read_unlock(dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(dentry->d_sb);
 	return err;
 }
diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index aed4d39..edea1a4 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -433,11 +433,11 @@ static int unionfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 
 	unionfs_lock_dentry(dentry);
 	err = __unionfs_d_revalidate_chain(dentry, nd, false);
-	unionfs_unlock_dentry(dentry);
 	if (likely(err > 0)) { /* true==1: dentry is valid */
 		unionfs_check_dentry(dentry);
 		unionfs_check_nd(nd);
 	}
+	unionfs_unlock_dentry(dentry);
 
 	unionfs_read_unlock(dentry->d_sb);
 
diff --git a/fs/unionfs/file.c b/fs/unionfs/file.c
index 809e0f1..cfbfb8e 100644
--- a/fs/unionfs/file.c
+++ b/fs/unionfs/file.c
@@ -32,8 +32,8 @@ static ssize_t unionfs_read(struct file *file, char __user *buf,
 	err = do_sync_read(file, buf, count, ppos);
 
 out:
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;
 }
 
@@ -55,8 +55,8 @@ static ssize_t unionfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
 		err = wait_on_sync_kiocb(iocb);
 
 out:
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;
 }
 
@@ -127,13 +127,13 @@ static int unionfs_mmap(struct file *file, struct vm_area_struct *vma)
 	}
 
 out:
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	if (!err) {
 		/* copyup could cause parent dir times to change */
 		unionfs_copy_attr_times(file->f_path.dentry->d_parent->d_inode);
 		unionfs_check_file(file);
 		unionfs_check_dentry(file->f_path.dentry->d_parent);
 	}
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;
 }
 
@@ -180,8 +180,8 @@ int unionfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 	unionfs_copy_attr_times(inode);
 
 out:
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;
 }
 
@@ -226,8 +226,8 @@ int unionfs_fasync(int fd, struct file *file, int flag)
 	unionfs_copy_attr_times(inode);
 
 out:
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;
 }
 
diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index 223a64a..1708f40 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -158,8 +158,6 @@ out:
 
 	if (!err)
 		unionfs_postcopyup_setmnt(dentry);
-	unionfs_unlock_dentry(dentry);
-	unionfs_read_unlock(dentry->d_sb);
 
 	unionfs_check_inode(parent);
 	if (!err) {
@@ -167,6 +165,8 @@ out:
 		unionfs_check_nd(nd);
 	}
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
+	unionfs_read_unlock(dentry->d_sb);
 	return err;
 }
 
@@ -206,13 +206,14 @@ static struct dentry *unionfs_lookup(struct inode *parent,
 			dentry = ret;
 		/* parent times may have changed */
 		unionfs_copy_attr_times(dentry->d_parent->d_inode);
-		unionfs_unlock_dentry(dentry);
 	}
 
 	unionfs_check_inode(parent);
 	unionfs_check_dentry(dentry);
 	unionfs_check_dentry(dentry->d_parent);
 	unionfs_check_nd(nd);
+	if (!IS_ERR(ret))
+		unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 
 	return ret;
@@ -356,12 +357,12 @@ out:
 	if (!err)
 		unionfs_postcopyup_setmnt(new_dentry);
 
-	unionfs_unlock_dentry(new_dentry);
-	unionfs_unlock_dentry(old_dentry);
-
 	unionfs_check_inode(dir);
 	unionfs_check_dentry(new_dentry);
 	unionfs_check_dentry(old_dentry);
+
+	unionfs_unlock_dentry(new_dentry);
+	unionfs_unlock_dentry(old_dentry);
 	unionfs_read_unlock(old_dentry->d_sb);
 
 	return err;
@@ -522,10 +523,10 @@ out:
 	kfree(name);
 	if (!err)
 		unionfs_postcopyup_setmnt(dentry);
-	unionfs_unlock_dentry(dentry);
 
 	unionfs_check_inode(dir);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 
 	return err;
@@ -675,9 +676,9 @@ out:
 
 	if (!err)
 		unionfs_copy_attr_times(dentry->d_inode);
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_inode(parent);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 
 	return err;
@@ -805,10 +806,10 @@ out:
 
 	if (!err)
 		unionfs_postcopyup_setmnt(dentry);
-	unionfs_unlock_dentry(dentry);
 
 	unionfs_check_inode(dir);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 
 	return err;
@@ -843,8 +844,8 @@ static int unionfs_readlink(struct dentry *dentry, char __user *buf,
 					lower_dentry->d_inode);
 
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 
 	return err;
@@ -906,11 +907,11 @@ static void unionfs_put_link(struct dentry *dentry, struct nameidata *nd,
 	if (unlikely(!__unionfs_d_revalidate_chain(dentry, nd, false)))
 		printk(KERN_ERR
 		       "unionfs: put_link failed to revalidate dentry\n");
-	unionfs_unlock_dentry(dentry);
 
 	unionfs_check_dentry(dentry);
 	unionfs_check_nd(nd);
 	kfree(nd_get_link(nd));
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 }
 
@@ -1090,9 +1091,9 @@ static int unionfs_setattr(struct dentry *dentry, struct iattr *ia)
 	/* if setattr succeeded, then parent dir may have changed */
 	unionfs_copy_attr_times(dentry->d_parent->d_inode);
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
 	unionfs_check_dentry(dentry->d_parent);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 
 	return err;
diff --git a/fs/unionfs/mmap.c b/fs/unionfs/mmap.c
index ef8822f..4918f77 100644
--- a/fs/unionfs/mmap.c
+++ b/fs/unionfs/mmap.c
@@ -296,8 +296,8 @@ out:
 	if (err < 0)
 		ClearPageUptodate(page);
 
-	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	unionfs_check_file(file);
+	unionfs_read_unlock(file->f_path.dentry->d_sb);
 	return err;		/* assume all is ok */
 }
 
diff --git a/fs/unionfs/super.c b/fs/unionfs/super.c
index 70487bf..88f77d7 100644
--- a/fs/unionfs/super.c
+++ b/fs/unionfs/super.c
@@ -153,8 +153,8 @@ static int unionfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	memset(&buf->f_spare, 0, sizeof(buf->f_spare));
 
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(sb);
 	return err;
 }
@@ -797,8 +797,8 @@ out_free:
 	kfree(new_data);
 	kfree(new_lower_inodes);
 out_error:
-	unionfs_write_unlock(sb);
 	unionfs_check_dentry(sb->s_root);
+	unionfs_write_unlock(sb);
 	return err;
 }
 
diff --git a/fs/unionfs/xattr.c b/fs/unionfs/xattr.c
index 602cedf..00c6d0d 100644
--- a/fs/unionfs/xattr.c
+++ b/fs/unionfs/xattr.c
@@ -58,8 +58,8 @@ ssize_t unionfs_getxattr(struct dentry *dentry, const char *name, void *value,
 	err = vfs_getxattr(lower_dentry, (char *) name, value, size);
 
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 	return err;
 }
@@ -88,8 +88,8 @@ int unionfs_setxattr(struct dentry *dentry, const char *name,
 			   size, flags);
 
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 	return err;
 }
@@ -116,8 +116,8 @@ int unionfs_removexattr(struct dentry *dentry, const char *name)
 	err = vfs_removexattr(lower_dentry, (char *) name);
 
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 	return err;
 }
@@ -146,8 +146,8 @@ ssize_t unionfs_listxattr(struct dentry *dentry, char *list, size_t size)
 	err = vfs_listxattr(lower_dentry, encoded_list, size);
 
 out:
-	unionfs_unlock_dentry(dentry);
 	unionfs_check_dentry(dentry);
+	unionfs_unlock_dentry(dentry);
 	unionfs_read_unlock(dentry->d_sb);
 	return err;
 }
-- 
1.5.2.2

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