ceph_add_cap says in its function documentation that the caller should hold the read lock on the session snap_rwsem. Furthermore, not only ceph_add_cap needs that lock, when it calls to ceph_lookup_snap_realm it eventually calls ceph_get_snap_realm which states via lockdep that snap_rwsem needs to be held. handle_cap_export calls ceph_add_cap without that mdsc->snap_rwsem held. Thus, since ceph_get_snap_realm and ceph_add_cap both need the lock, the common place to acquire that lock is inside handle_cap_export. Signed-off-by: Niels Dossche <dossche.niels@gmail.com> Reviewed-by: Xiubo Li <xiubli@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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.
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