tree d6c87569edb074ddd6edb3b88eb3105abefb3d6b
parent 5b2cccd32c668de6bd1979545184cd7f0260f053
author Amir Goldstein <amir73il@gmail.com> 1520603462 +0200
committer Miklos Szeredi <mszeredi@redhat.com> 1523527489 +0200

ovl: do not try to reconnect a disconnected origin dentry

On lookup of non directory, we try to decode the origin file handle
stored in upper inode. The origin file handle is supposed to be decoded
to a disconnected non-dir dentry, which is fine, because we only need
the lower inode of a copy up origin.

However, if the origin file handle somehow turns out to be a directory
we pay the expensive cost of reconnecting the directory dentry, only to
get a mismatch file type and drop the dentry.

Optimize this case by explicitly opting out of reconnecting the dentry.
Opting-out of reconnect is done by passing a NULL acceptable callback
to exportfs_decode_fh().

While the case described above is a strange corner case that does not
really need to be optimized, the API added for this optimization will
be used by a following patch to optimize a more common case of decoding
an overlayfs file handle.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>