092401142b
commit 4a4b8721f1a5e4b01e45b3153c68d5a1014b25de upstream.
The stated reasons for separating fscrypt_master_key::mk_secret_sem from
the standard semaphore contained in every 'struct key' no longer apply.
First, due to commit a992b20cd4ee ("fscrypt: add
fscrypt_prepare_new_inode() and fscrypt_set_context()"),
fscrypt_get_encryption_info() is no longer called from within a
filesystem transaction.
Second, due to commit d3ec10aa9581 ("KEYS: Don't write out to userspace
while holding key semaphore"), the semaphore for the "keyring" key type
no longer ranks above page faults.
That leaves performance as the only possible reason to keep the separate
mk_secret_sem. Specifically, having mk_secret_sem reduces the
contention between setup_file_encryption_key() and
FS_IOC_{ADD,REMOVE}_ENCRYPTION_KEY. However, these ioctls aren't
executed often, so this doesn't seem to be worth the extra complexity.
Therefore, simplify the locking design by just using key->sem instead of
mk_secret_sem.
Link: https://lore.kernel.org/r/20201117032626.320275-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
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
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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.