parallel lookups: actual switch to rwsem

ta-da!

The main issue is the lack of down_write_killable(), so the places
like readdir.c switched to plain inode_lock(); once killable
variants of rwsem primitives appear, that'll be dealt with.

lockdep side also might need more work

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 11 insertions, 7 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 5a23806ae418..0b8ba717175b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -837,9 +837,11 @@ static noinline int btrfs_mksubvol(struct path *parent,
         struct dentry *dentry;
         int error;
 
-        error = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
-        if (error == -EINTR)
-                return error;
+        inode_lock_nested(dir, I_MUTEX_PARENT);
+        // XXX: should've been
+        // mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
+        // if (error == -EINTR)
+        //      return error;
 
         dentry = lookup_one_len(name, parent->dentry, namelen);
         error = PTR_ERR(dentry);
@@ -2366,9 +2368,11 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
                 goto out;
 
 
-        err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
-        if (err == -EINTR)
-                goto out_drop_write;
+        inode_lock_nested(dir, I_MUTEX_PARENT);
+        // XXX: should've been
+        // err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
+        // if (err == -EINTR)
+        //      goto out_drop_write;
         dentry = lookup_one_len(vol_args->name, parent, namelen);
         if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);
@@ -2558,7 +2562,7 @@ out_dput:
         dput(dentry);
 out_unlock_dir:
         inode_unlock(dir);
-out_drop_write:
+//out_drop_write:
         mnt_drop_write_file(file);
 out:
         kfree(vol_args);