[ Upstream commit ed77e80e14a3cd55c73848b9e8043020e717ce12 ]
Modify get_file_raw_ptr to use task_lookup_fd_rcu. The helper
task_lookup_fd_rcu does the work of taking the task lock and verifying
that task->files != NULL and then calls files_lookup_fd_rcu. So let
use the helper to make a simpler implementation of get_file_raw_ptr.
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Link: https://lkml.kernel.org/r/20201120231441.29911-13-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit f36c2943274199cb8aef32ac96531ffb7c4b43d0 ]
This change renames fcheck_files to files_lookup_fd_rcu. All of the
remaining callers take the rcu_read_lock before calling this function
so the _rcu suffix is appropriate. This change also tightens up the
debug check to verify that all callers hold the rcu_read_lock.
All callers that used to call files_check with the files->file_lock
held have now been changed to call files_lookup_fd_locked.
This change of name has helped remind me of which locks and which
guarantees are in place helping me to catch bugs later in the
patchset.
The need for better names became apparent in the last round of
discussion of this set of changes[1].
[1] https://lkml.kernel.org/r/CAHk-=wj8BQbgJFLa+J0e=iT-1qpmCRTbPAJ8gd6MJQ=kbRPqyQ@mail.gmail.com
Link: https://lkml.kernel.org/r/20201120231441.29911-9-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit f43c283a89a7dc531a47d4b1e001503cf3dc3234 ]
Use the helper fget_task and simplify the code.
As well as simplifying the code this removes one unnecessary increment of
struct files_struct. This unnecessary increment of files_struct.count can
result in exec unnecessarily unsharing files_struct and breaking posix
locks, and it can result in fget_light having to fallback to fget reducing
performance.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-4-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-4-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
