f2fs: call unlock_new_inode() before d_instantiate()

Cherry-pick from origin/upstream-f2fs-stable-linux-4.9.y:
  e605f836c89e ("f2fs: call unlock_new_inode() before d_instantiate()")

xfstest generic/429 sometimes hangs on f2fs, caused by a thread being
unable to take a directory's i_rwsem for write in vfs_rmdir().  In the
test, one thread repeatedly creates and removes a directory, and other
threads repeatedly look up a file in the directory.  The bug is that
f2fs_mkdir() calls d_instantiate() before unlock_new_inode(), resulting
in the directory inode being exposed to lookups before it has been fully
initialized.  And with CONFIG_DEBUG_LOCK_ALLOC, unlock_new_inode()
reinitializes ->i_rwsem, corrupting its state when it is already held.

Fix it by calling unlock_new_inode() before d_instantiate().  This
matches what other filesystems do.

Fixes: 57397d86c62d ("f2fs: add inode operations for special inodes")
Change-Id: I3f3a17bd5c22e69f685f4d00c2210876fb29a846
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 2d49029..392d1ed 100644 (file)
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -294,8 +294,8 @@ static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 
        alloc_nid_done(sbi, ino);
 
-       d_instantiate(dentry, inode);
        unlock_new_inode(inode);
+       d_instantiate(dentry, inode);
 
        if (IS_DIRSYNC(dir))
                f2fs_sync_fs(sbi->sb, 1);
@@ -597,8 +597,8 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
        err = page_symlink(inode, disk_link.name, disk_link.len);
 
 err_out:
-       d_instantiate(dentry, inode);
        unlock_new_inode(inode);
+       d_instantiate(dentry, inode);
 
        /*
         * Let's flush symlink data in order to avoid broken symlink as much as
@@ -661,8 +661,8 @@ static int f2fs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 
        alloc_nid_done(sbi, inode->i_ino);
 
-       d_instantiate(dentry, inode);
        unlock_new_inode(inode);
+       d_instantiate(dentry, inode);
 
        if (IS_DIRSYNC(dir))
                f2fs_sync_fs(sbi->sb, 1);
@@ -713,8 +713,8 @@ static int f2fs_mknod(struct inode *dir, struct dentry *dentry,
 
        alloc_nid_done(sbi, inode->i_ino);
 
-       d_instantiate(dentry, inode);
        unlock_new_inode(inode);
+       d_instantiate(dentry, inode);
 
        if (IS_DIRSYNC(dir))
                f2fs_sync_fs(sbi->sb, 1);