10629c04b3
commit 2a3dcbccd64ba35c045fac92272ff981c4cbef44 upstream. Decrement the refcount of the parent dentry's fid after walking each path component during a full path walk for a lookup. Failure to do so can lead to fids that are not clunked until the filesystem is unmounted, as indicated by this warning: 9pnet: found fid 3 not clunked The improper refcounting after walking resulted in open(2) returning -EIO on any directories underneath the mount point when using the virtio transport. When using the fd transport, there's no apparent issue until the filesytem is unmounted and the warning above is emitted to the logs. In some cases, the user may not yet be attached to the filesystem and a new root fid, associated with the user, is created and attached to the root dentry before the full path walk is performed. Increment the new root fid's refcount to two in that situation so that it can be safely decremented to one after it is used for the walk operation. The new fid will still be attached to the root dentry when v9fs_fid_lookup_with_uid() returns so a final refcount of one is correct/expected. Link: https://lkml.kernel.org/r/20220527000003.355812-2-tyhicks@linux.microsoft.com Link: https://lkml.kernel.org/r/20220612085330.1451496-4-asmadeus@codewreck.org Fixes: 6636b6dcc3db ("9p: add refcount to p9_fid struct") Cc: stable@vger.kernel.org Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com> Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com> [Dominique: fix clunking fid multiple times discussed in second link] Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.