[PATCH 3/6] erofs: remove tagged pointer helpers

Gao Xiang
2023-02-04T09:31:08Z

Just open-code the remaining one to simplify the code.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
fs/erofs/tagptr.h | 107 ----------------------------------------------
fs/erofs/zdata.c | 26 +++--------
fs/erofs/zdata.h | 1 -
3 files changed, 6 insertions(+), 128 deletions(-)
delete mode 100644 fs/erofs/tagptr.h

diff --git a/fs/erofs/tagptr.h b/fs/erofs/tagptr.h
deleted file mode 100644
index 64ceb7270b5c..000000000000
--- a/fs/erofs/tagptr.h
+++ /dev/null
@@ -1,107 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * A tagged pointer implementation
- */
-#ifndef __EROFS_FS_TAGPTR_H
-#define __EROFS_FS_TAGPTR_H
-
-#include <linux/types.h>
-#include <linux/build_bug.h>
-
-/*
- * the name of tagged pointer types are tagptr{1, 2, 3...}_t
- * avoid directly using the internal structs __tagptr{1, 2, 3...}
- */
-#define __MAKE_TAGPTR(n) \
-typedef struct __tagptr##n { \
- uintptr_t v; \
-} tagptr##n##_t;
-
-__MAKE_TAGPTR(1)
-__MAKE_TAGPTR(2)
-__MAKE_TAGPTR(3)
-__MAKE_TAGPTR(4)
-
-#undef __MAKE_TAGPTR
-
-extern void __compiletime_error("bad tagptr tags")
- __bad_tagptr_tags(void);
-
-extern void __compiletime_error("bad tagptr type")
- __bad_tagptr_type(void);
-
-/* fix the broken usage of "#define tagptr2_t tagptr3_t" by users */
-#define __tagptr_mask_1(ptr, n) \
- __builtin_types_compatible_p(typeof(ptr), struct __tagptr##n) ? \
- (1UL << (n)) - 1 :
-
-#define __tagptr_mask(ptr) (\
- __tagptr_mask_1(ptr, 1) ( \
- __tagptr_mask_1(ptr, 2) ( \
- __tagptr_mask_1(ptr, 3) ( \
- __tagptr_mask_1(ptr, 4) ( \
- __bad_tagptr_type(), 0)))))
-
-/* generate a tagged pointer from a raw value */
-#define tagptr_init(type, val) \
- ((typeof(type)){ .v = (uintptr_t)(val) })
-
-/*
- * directly cast a tagged pointer to the native pointer type, which
- * could be used for backward compatibility of existing code.
- */
-#define tagptr_cast_ptr(tptr) ((void *)(tptr).v)
-
-/* encode tagged pointers */
-#define tagptr_fold(type, ptr, _tags) ({ \
- const typeof(_tags) tags = (_tags); \
- if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(type))) \
- __bad_tagptr_tags(); \
-tagptr_init(type, (uintptr_t)(ptr) | tags); })
-
-/* decode tagged pointers */
-#define tagptr_unfold_ptr(tptr) \
- ((void *)((tptr).v & ~__tagptr_mask(tptr)))
-
-#define tagptr_unfold_tags(tptr) \
- ((tptr).v & __tagptr_mask(tptr))
-
-/* operations for the tagger pointer */
-#define tagptr_eq(_tptr1, _tptr2) ({ \
- typeof(_tptr1) tptr1 = (_tptr1); \
- typeof(_tptr2) tptr2 = (_tptr2); \
- (void)(&tptr1 == &tptr2); \
-(tptr1).v == (tptr2).v; })
-
-/* lock-free CAS operation */
-#define tagptr_cmpxchg(_ptptr, _o, _n) ({ \
- typeof(_ptptr) ptptr = (_ptptr); \
- typeof(_o) o = (_o); \
- typeof(_n) n = (_n); \
- (void)(&o == &n); \
- (void)(&o == ptptr); \
-tagptr_init(o, cmpxchg(&ptptr->v, o.v, n.v)); })
-
-/* wrap WRITE_ONCE if atomic update is needed */
-#define tagptr_replace_tags(_ptptr, tags) ({ \
- typeof(_ptptr) ptptr = (_ptptr); \
- *ptptr = tagptr_fold(*ptptr, tagptr_unfold_ptr(*ptptr), tags); \
-*ptptr; })
-
-#define tagptr_set_tags(_ptptr, _tags) ({ \
- typeof(_ptptr) ptptr = (_ptptr); \
- const typeof(_tags) tags = (_tags); \
- if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \
- __bad_tagptr_tags(); \
- ptptr->v |= tags; \
-*ptptr; })
-
-#define tagptr_clear_tags(_ptptr, _tags) ({ \
- typeof(_ptptr) ptptr = (_ptptr); \
- const typeof(_tags) tags = (_tags); \
- if (__builtin_constant_p(tags) && (tags & ~__tagptr_mask(*ptptr))) \
- __bad_tagptr_tags(); \
- ptptr->v &= ~tags; \
-*ptptr; })
-
-#endif /* __EROFS_FS_TAGPTR_H */
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index f015a90839f6..ae97e3b627cb 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -175,15 +175,6 @@ static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
DBG_BUGON(1);
}

-/*
- * tagged pointer with 1-bit tag for all compressed pages
- * tag 0 - the page is just found with an extra page reference
- */
-typedef tagptr1_t compressed_page_t;
-
-#define tag_compressed_page_justfound(page) \
- tagptr_fold(compressed_page_t, page, 1)
-
static struct workqueue_struct *z_erofs_workqueue __read_mostly;

void z_erofs_exit_zip_subsystem(void)
@@ -319,7 +310,7 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,

for (i = 0; i < pcl->pclusterpages; ++i) {
struct page *page;
- compressed_page_t t;
+ void *t; /* mark pages just found for debugging */
struct page *newpage = NULL;

/* the compressed page was loaded before */
@@ -329,7 +320,7 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
page = find_get_page(mc, pcl->obj.index + i);

if (page) {
- t = tag_compressed_page_justfound(page);
+ t = (void *)((unsigned long)page | 1);
} else {
/* I/O is needed, no possible to decompress directly */
standalone = false;
@@ -345,11 +336,10 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
if (!newpage)
continue;
set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE);
- t = tag_compressed_page_justfound(newpage);
+ t = (void *)((unsigned long)newpage | 1);
}

- if (!cmpxchg_relaxed(&pcl->compressed_bvecs[i].page, NULL,
- tagptr_cast_ptr(t)))
+ if (!cmpxchg_relaxed(&pcl->compressed_bvecs[i].page, NULL, t))
continue;

if (page)
@@ -1192,8 +1182,6 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,

struct address_space *mapping;
struct page *oldpage, *page;
-
- compressed_page_t t;
int justfound;

repeat:
@@ -1203,10 +1191,8 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
if (!page)
goto out_allocpage;

- /* process the target tagged pointer */
- t = tagptr_init(compressed_page_t, page);
- justfound = tagptr_unfold_tags(t);
- page = tagptr_unfold_ptr(t);
+ justfound = (unsigned long)page & 1UL;
+ page = (struct page *)((unsigned long)page & ~1UL);

/*
* preallocated cached pages, which is used to avoid direct reclaim
diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
index b139de5473a9..f196a729c7e8 100644
--- a/fs/erofs/zdata.h
+++ b/fs/erofs/zdata.h
@@ -7,7 +7,6 @@
#define __EROFS_FS_ZDATA_H

#include "internal.h"
-#include "tagptr.h"

#define Z_EROFS_PCLUSTER_MAX_PAGES (Z_EROFS_PCLUSTER_MAX_SIZE / PAGE_SIZE)
#define Z_EROFS_INLINE_BVECS 2
--
2.24.4