staging: erofs: <linux/tagptr.h>: introduce tagged pointer

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Currently kernel has scattered tagged pointer usages hacked
by hand in plain code, without a unique and portable functionset
to highlight the tagged pointer itself and wrap these hacked code
in order to clean up all over meaningless magic masks.

Therefore, this patch introduces simple generic methods to fold
tags into a pointer integer. It currently supports the last n bits
of the pointer for tags, which can be selected by users.

In addition, it will also be used for the upcoming EROFS filesystem,
which heavily uses tagged pointer approach for high performance
and reducing extra memory allocation.

Link: https://en.wikipedia.org/wiki/Tagged_pointer

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Gao Xiang 2018-07-26 20:21:56 +08:00 • committed by Greg Kroah-Hartman

parent 13f06f48f7

commit b8b58b3280

1 changed files with 110 additions and 0 deletions

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drivers/staging/erofs/include/linux/tagptr.h

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