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Message-ID: <20220715150737.00006764.zbestahu@gmail.com>
Date: Fri, 15 Jul 2022 15:07:37 +0800
From: Yue Hu <zbestahu@...il.com>
To: Gao Xiang <hsiangkao@...ux.alibaba.com>
Cc: linux-erofs@...ts.ozlabs.org, Chao Yu <chao@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, zhangwen@...lpad.com
Subject: Re: [PATCH 05/16] erofs: drop the old pagevec approach
On Thu, 14 Jul 2022 21:20:40 +0800
Gao Xiang <hsiangkao@...ux.alibaba.com> wrote:
> Remove the old pagevec approach but keep z_erofs_page_type for now.
> It will be reworked in the following commits as well.
>
> Also rename Z_EROFS_NR_INLINE_PAGEVECS as Z_EROFS_INLINE_BVECS with
> the new value 2 since it's actually enough to bootstrap.
I notice there are 2 comments as below which still use pagevec, should we
update it as well?
[1]
* pagevec) since it can be directly decoded without I/O submission.
[2]
* for inplace I/O or pagevec (should be processed in strict order.)
BTW, utils.c includes needles <pagevec.h>, we can remove it along with the patchset
or remove it later.
>
> Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
> ---
> fs/erofs/zdata.c | 17 +++--
> fs/erofs/zdata.h | 9 +--
> fs/erofs/zpvec.h | 159 -----------------------------------------------
> 3 files changed, 16 insertions(+), 169 deletions(-)
> delete mode 100644 fs/erofs/zpvec.h
>
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index f52c54058f31..e96704db106e 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -27,6 +27,17 @@ static struct z_erofs_pcluster_slab pcluster_pool[] __read_mostly = {
> _PCLP(Z_EROFS_PCLUSTER_MAX_PAGES)
> };
>
> +/* page type in pagevec for decompress subsystem */
> +enum z_erofs_page_type {
> + /* including Z_EROFS_VLE_PAGE_TAIL_EXCLUSIVE */
> + Z_EROFS_PAGE_TYPE_EXCLUSIVE,
> +
> + Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED,
> +
> + Z_EROFS_VLE_PAGE_TYPE_HEAD,
> + Z_EROFS_VLE_PAGE_TYPE_MAX
> +};
> +
> struct z_erofs_bvec_iter {
> struct page *bvpage;
> struct z_erofs_bvset *bvset;
> @@ -273,7 +284,6 @@ struct z_erofs_decompress_frontend {
> struct inode *const inode;
> struct erofs_map_blocks map;
> struct z_erofs_bvec_iter biter;
> - struct z_erofs_pagevec_ctor vector;
>
> struct page *candidate_bvpage;
> struct z_erofs_pcluster *pcl, *tailpcl;
> @@ -636,7 +646,7 @@ static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
> return ret;
> }
> z_erofs_bvec_iter_begin(&fe->biter, &fe->pcl->bvset,
> - Z_EROFS_NR_INLINE_PAGEVECS, fe->pcl->vcnt);
> + Z_EROFS_INLINE_BVECS, fe->pcl->vcnt);
> /* since file-backed online pages are traversed in reverse order */
> fe->icpage_ptr = fe->pcl->compressed_pages +
> z_erofs_pclusterpages(fe->pcl);
> @@ -871,8 +881,7 @@ static int z_erofs_parse_out_bvecs(struct z_erofs_pcluster *pcl,
> struct page *old_bvpage;
> int i, err = 0;
>
> - z_erofs_bvec_iter_begin(&biter, &pcl->bvset,
> - Z_EROFS_NR_INLINE_PAGEVECS, 0);
> + z_erofs_bvec_iter_begin(&biter, &pcl->bvset, Z_EROFS_INLINE_BVECS, 0);
> for (i = 0; i < pcl->vcnt; ++i) {
> struct z_erofs_bvec bvec;
> unsigned int pagenr;
> diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
> index d03e333e4fde..a755c5a44d87 100644
> --- a/fs/erofs/zdata.h
> +++ b/fs/erofs/zdata.h
> @@ -7,10 +7,10 @@
> #define __EROFS_FS_ZDATA_H
>
> #include "internal.h"
> -#include "zpvec.h"
> +#include "tagptr.h"
>
> #define Z_EROFS_PCLUSTER_MAX_PAGES (Z_EROFS_PCLUSTER_MAX_SIZE / PAGE_SIZE)
> -#define Z_EROFS_NR_INLINE_PAGEVECS 3
> +#define Z_EROFS_INLINE_BVECS 2
>
> #define Z_EROFS_PCLUSTER_FULL_LENGTH 0x00000001
> #define Z_EROFS_PCLUSTER_LENGTH_BIT 1
> @@ -34,7 +34,7 @@ struct name { \
> struct z_erofs_bvec bvec[total]; \
> };
> __Z_EROFS_BVSET(z_erofs_bvset,)
> -__Z_EROFS_BVSET(z_erofs_bvset_inline, Z_EROFS_NR_INLINE_PAGEVECS)
> +__Z_EROFS_BVSET(z_erofs_bvset_inline, Z_EROFS_INLINE_BVECS)
>
> /*
> * Structure fields follow one of the following exclusion rules.
> @@ -69,9 +69,6 @@ struct z_erofs_pcluster {
> unsigned short nr_pages;
>
> union {
> - /* L: inline a certain number of pagevecs for bootstrap */
> - erofs_vtptr_t pagevec[Z_EROFS_NR_INLINE_PAGEVECS];
> -
> /* L: inline a certain number of bvec for bootstrap */
> struct z_erofs_bvset_inline bvset;
>
> diff --git a/fs/erofs/zpvec.h b/fs/erofs/zpvec.h
> deleted file mode 100644
> index b05464f4a808..000000000000
> --- a/fs/erofs/zpvec.h
> +++ /dev/null
> @@ -1,159 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0-only */
> -/*
> - * Copyright (C) 2018 HUAWEI, Inc.
> - * https://www.huawei.com/
> - */
> -#ifndef __EROFS_FS_ZPVEC_H
> -#define __EROFS_FS_ZPVEC_H
> -
> -#include "tagptr.h"
> -
> -/* page type in pagevec for decompress subsystem */
> -enum z_erofs_page_type {
> - /* including Z_EROFS_VLE_PAGE_TAIL_EXCLUSIVE */
> - Z_EROFS_PAGE_TYPE_EXCLUSIVE,
> -
> - Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED,
> -
> - Z_EROFS_VLE_PAGE_TYPE_HEAD,
> - Z_EROFS_VLE_PAGE_TYPE_MAX
> -};
> -
> -extern void __compiletime_error("Z_EROFS_PAGE_TYPE_EXCLUSIVE != 0")
> - __bad_page_type_exclusive(void);
> -
> -/* pagevec tagged pointer */
> -typedef tagptr2_t erofs_vtptr_t;
> -
> -/* pagevec collector */
> -struct z_erofs_pagevec_ctor {
> - struct page *curr, *next;
> - erofs_vtptr_t *pages;
> -
> - unsigned int nr, index;
> -};
> -
> -static inline void z_erofs_pagevec_ctor_exit(struct z_erofs_pagevec_ctor *ctor,
> - bool atomic)
> -{
> - if (!ctor->curr)
> - return;
> -
> - if (atomic)
> - kunmap_atomic(ctor->pages);
> - else
> - kunmap(ctor->curr);
> -}
> -
> -static inline struct page *
> -z_erofs_pagevec_ctor_next_page(struct z_erofs_pagevec_ctor *ctor,
> - unsigned int nr)
> -{
> - unsigned int index;
> -
> - /* keep away from occupied pages */
> - if (ctor->next)
> - return ctor->next;
> -
> - for (index = 0; index < nr; ++index) {
> - const erofs_vtptr_t t = ctor->pages[index];
> - const unsigned int tags = tagptr_unfold_tags(t);
> -
> - if (tags == Z_EROFS_PAGE_TYPE_EXCLUSIVE)
> - return tagptr_unfold_ptr(t);
> - }
> - DBG_BUGON(nr >= ctor->nr);
> - return NULL;
> -}
> -
> -static inline void
> -z_erofs_pagevec_ctor_pagedown(struct z_erofs_pagevec_ctor *ctor,
> - bool atomic)
> -{
> - struct page *next = z_erofs_pagevec_ctor_next_page(ctor, ctor->nr);
> -
> - z_erofs_pagevec_ctor_exit(ctor, atomic);
> -
> - ctor->curr = next;
> - ctor->next = NULL;
> - ctor->pages = atomic ?
> - kmap_atomic(ctor->curr) : kmap(ctor->curr);
> -
> - ctor->nr = PAGE_SIZE / sizeof(struct page *);
> - ctor->index = 0;
> -}
> -
> -static inline void z_erofs_pagevec_ctor_init(struct z_erofs_pagevec_ctor *ctor,
> - unsigned int nr,
> - erofs_vtptr_t *pages,
> - unsigned int i)
> -{
> - ctor->nr = nr;
> - ctor->curr = ctor->next = NULL;
> - ctor->pages = pages;
> -
> - if (i >= nr) {
> - i -= nr;
> - z_erofs_pagevec_ctor_pagedown(ctor, false);
> - while (i > ctor->nr) {
> - i -= ctor->nr;
> - z_erofs_pagevec_ctor_pagedown(ctor, false);
> - }
> - }
> - ctor->next = z_erofs_pagevec_ctor_next_page(ctor, i);
> - ctor->index = i;
> -}
> -
> -static inline bool z_erofs_pagevec_enqueue(struct z_erofs_pagevec_ctor *ctor,
> - struct page *page,
> - enum z_erofs_page_type type,
> - bool pvec_safereuse)
> -{
> - if (!ctor->next) {
> - /* some pages cannot be reused as pvec safely without I/O */
> - if (type == Z_EROFS_PAGE_TYPE_EXCLUSIVE && !pvec_safereuse)
> - type = Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED;
> -
> - if (type != Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
> - ctor->index + 1 == ctor->nr)
> - return false;
> - }
> -
> - if (ctor->index >= ctor->nr)
> - z_erofs_pagevec_ctor_pagedown(ctor, false);
> -
> - /* exclusive page type must be 0 */
> - if (Z_EROFS_PAGE_TYPE_EXCLUSIVE != (uintptr_t)NULL)
> - __bad_page_type_exclusive();
> -
> - /* should remind that collector->next never equal to 1, 2 */
> - if (type == (uintptr_t)ctor->next) {
> - ctor->next = page;
> - }
> - ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, page, type);
> - return true;
> -}
> -
> -static inline struct page *
> -z_erofs_pagevec_dequeue(struct z_erofs_pagevec_ctor *ctor,
> - enum z_erofs_page_type *type)
> -{
> - erofs_vtptr_t t;
> -
> - if (ctor->index >= ctor->nr) {
> - DBG_BUGON(!ctor->next);
> - z_erofs_pagevec_ctor_pagedown(ctor, true);
> - }
> -
> - t = ctor->pages[ctor->index];
> -
> - *type = tagptr_unfold_tags(t);
> -
> - /* should remind that collector->next never equal to 1, 2 */
> - if (*type == (uintptr_t)ctor->next)
> - ctor->next = tagptr_unfold_ptr(t);
> -
> - ctor->pages[ctor->index++] = tagptr_fold(erofs_vtptr_t, NULL, 0);
> - return tagptr_unfold_ptr(t);
> -}
> -#endif
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