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EROFS filesystem has been merged into linux-staging for a year. EROFS is designed to be a better solution of saving extra storage space with guaranteed end-to-end performance for read-only files with the help of reduced metadata, fixed-sized output compression and decompression inplace technologies. In the past year, EROFS was greatly improved by many people as a staging driver, self-tested, betaed by a large number of our internal users, successfully applied to almost all in-service HUAWEI smartphones as the part of EMUI 9.1 and proven to be stable enough to be moved out of staging. EROFS is a self-contained filesystem driver. Although there are still some TODOs to be more generic, we have a dedicated team actively keeping on working on EROFS in order to make it better with the evolution of Linux kernel as the other in-kernel filesystems. As Pavel suggested, it's better to do as one commit since git can do moves and all histories will be saved in this way. Let's promote it from staging and enhance it more actively as a "real" part of kernel for more wider scenarios! Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Pavel Machek <pavel@denx.de> Cc: David Sterba <dsterba@suse.cz> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Darrick J . Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Richard Weinberger <richard@nod.at> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Chao Yu <yuchao0@huawei.com> Cc: Miao Xie <miaoxie@huawei.com> Cc: Li Guifu <bluce.liguifu@huawei.com> Cc: Fang Wei <fangwei1@huawei.com> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com> Link: https://lore.kernel.org/r/20190822213659.5501-1-hsiangkao@aol.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
111 lines
3.0 KiB
C
111 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* A tagged pointer implementation
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*
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* Copyright (C) 2018 Gao Xiang <gaoxiang25@huawei.com>
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*/
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#ifndef __EROFS_FS_TAGPTR_H
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#define __EROFS_FS_TAGPTR_H
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#include <linux/types.h>
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#include <linux/build_bug.h>
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/*
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* the name of tagged pointer types are tagptr{1, 2, 3...}_t
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* avoid directly using the internal structs __tagptr{1, 2, 3...}
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*/
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#define __MAKE_TAGPTR(n) \
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typedef struct __tagptr##n { \
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uintptr_t v; \
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} tagptr##n##_t;
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__MAKE_TAGPTR(1)
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__MAKE_TAGPTR(2)
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__MAKE_TAGPTR(3)
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__MAKE_TAGPTR(4)
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#undef __MAKE_TAGPTR
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extern void __compiletime_error("bad tagptr tags")
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__bad_tagptr_tags(void);
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extern void __compiletime_error("bad tagptr type")
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__bad_tagptr_type(void);
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/* fix the broken usage of "#define tagptr2_t tagptr3_t" by users */
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#define __tagptr_mask_1(ptr, n) \
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__builtin_types_compatible_p(typeof(ptr), struct __tagptr##n) ? \
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(1UL << (n)) - 1 :
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#define __tagptr_mask(ptr) (\
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__tagptr_mask_1(ptr, 1) ( \
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__tagptr_mask_1(ptr, 2) ( \
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__tagptr_mask_1(ptr, 3) ( \
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__tagptr_mask_1(ptr, 4) ( \
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__bad_tagptr_type(), 0)))))
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/* generate a tagged pointer from a raw value */
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#define tagptr_init(type, val) \
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((typeof(type)){ .v = (uintptr_t)(val) })
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/*
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* directly cast a tagged pointer to the native pointer type, which
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* could be used for backward compatibility of existing code.
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*/
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#define tagptr_cast_ptr(tptr) ((void *)(tptr).v)
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/* encode tagged pointers */
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#define tagptr_fold(type, ptr, _tags) ({ \
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const typeof(_tags) tags = (_tags); \
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if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(type))) \
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__bad_tagptr_tags(); \
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tagptr_init(type, (uintptr_t)(ptr) | tags); })
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/* decode tagged pointers */
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#define tagptr_unfold_ptr(tptr) \
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((void *)((tptr).v & ~__tagptr_mask(tptr)))
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#define tagptr_unfold_tags(tptr) \
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((tptr).v & __tagptr_mask(tptr))
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/* operations for the tagger pointer */
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#define tagptr_eq(_tptr1, _tptr2) ({ \
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typeof(_tptr1) tptr1 = (_tptr1); \
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typeof(_tptr2) tptr2 = (_tptr2); \
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(void)(&tptr1 == &tptr2); \
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(tptr1).v == (tptr2).v; })
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/* lock-free CAS operation */
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#define tagptr_cmpxchg(_ptptr, _o, _n) ({ \
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typeof(_ptptr) ptptr = (_ptptr); \
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typeof(_o) o = (_o); \
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typeof(_n) n = (_n); \
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(void)(&o == &n); \
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(void)(&o == ptptr); \
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tagptr_init(o, cmpxchg(&ptptr->v, o.v, n.v)); })
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/* wrap WRITE_ONCE if atomic update is needed */
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#define tagptr_replace_tags(_ptptr, tags) ({ \
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typeof(_ptptr) ptptr = (_ptptr); \
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*ptptr = tagptr_fold(*ptptr, tagptr_unfold_ptr(*ptptr), tags); \
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*ptptr; })
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#define tagptr_set_tags(_ptptr, _tags) ({ \
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typeof(_ptptr) ptptr = (_ptptr); \
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const typeof(_tags) tags = (_tags); \
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if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \
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__bad_tagptr_tags(); \
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ptptr->v |= tags; \
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*ptptr; })
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#define tagptr_clear_tags(_ptptr, _tags) ({ \
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typeof(_ptptr) ptptr = (_ptptr); \
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const typeof(_tags) tags = (_tags); \
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if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \
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__bad_tagptr_tags(); \
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ptptr->v &= ~tags; \
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*ptptr; })
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#endif /* __EROFS_FS_TAGPTR_H */
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