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Subject[PATCH 3/6] staging: erofs: drop multiref support temporarily
Date
Multiref support means that a compressed page could have
more than one reference, which is designed for on-disk data
deduplication. However, mkfs doesn't support this mode
at this moment, and the kernel implementation is also broken.

Let's drop multiref support. If it is fully implemented
in the future, it can be reverted later.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/unzip_vle.c | 36 +++++-------------------------------
drivers/staging/erofs/unzip_vle.h | 12 +-----------
2 files changed, 6 insertions(+), 42 deletions(-)

diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
index e820490..9fe18cd3 100644
--- a/drivers/staging/erofs/unzip_vle.c
+++ b/drivers/staging/erofs/unzip_vle.c
@@ -301,12 +301,9 @@ struct z_erofs_vle_work_finder {
grp = container_of(egrp, struct z_erofs_vle_workgroup, obj);
*f->grp_ret = grp;

-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
work = z_erofs_vle_grab_work(grp, f->pageofs);
+ /* if multiref is disabled, `primary' is always true */
primary = true;
-#else
- BUG();
-#endif

DBG_BUGON(work->pageofs != f->pageofs);

@@ -368,12 +365,9 @@ struct z_erofs_vle_work_finder {
struct z_erofs_vle_workgroup *grp = *f->grp_ret;
struct z_erofs_vle_work *work;

-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
+ /* if multiref is disabled, grp should never be nullptr */
BUG_ON(grp != NULL);
-#else
- if (grp != NULL)
- goto skip;
-#endif
+
/* no available workgroup, let's allocate one */
grp = kmem_cache_zalloc(z_erofs_workgroup_cachep, GFP_NOFS);
if (unlikely(grp == NULL))
@@ -396,13 +390,7 @@ struct z_erofs_vle_work_finder {
*f->hosted = true;

gnew = true;
-#ifdef CONFIG_EROFS_FS_ZIP_MULTIREF
-skip:
- /* currently unimplemented */
- BUG();
-#else
work = z_erofs_vle_grab_primary_work(grp);
-#endif
work->pageofs = f->pageofs;

mutex_init(&work->lock);
@@ -797,9 +785,7 @@ static int z_erofs_vle_unzip(struct super_block *sb,

struct z_erofs_pagevec_ctor ctor;
unsigned int nr_pages;
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
unsigned int sparsemem_pages = 0;
-#endif
struct page *pages_onstack[Z_EROFS_VLE_VMAP_ONSTACK_PAGES];
struct page **pages, **compressed_pages, *page;
unsigned int i, llen;
@@ -811,11 +797,7 @@ static int z_erofs_vle_unzip(struct super_block *sb,
int err;

might_sleep();
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
work = z_erofs_vle_grab_primary_work(grp);
-#else
- BUG();
-#endif
BUG_ON(!READ_ONCE(work->nr_pages));

mutex_lock(&work->lock);
@@ -866,13 +848,11 @@ static int z_erofs_vle_unzip(struct super_block *sb,
pagenr = z_erofs_onlinepage_index(page);

BUG_ON(pagenr >= nr_pages);
-
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
BUG_ON(pages[pagenr] != NULL);
- ++sparsemem_pages;
-#endif
+
pages[pagenr] = page;
}
+ sparsemem_pages = i;

z_erofs_pagevec_ctor_exit(&ctor, true);

@@ -902,10 +882,8 @@ static int z_erofs_vle_unzip(struct super_block *sb,
pagenr = z_erofs_onlinepage_index(page);

BUG_ON(pagenr >= nr_pages);
-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
BUG_ON(pages[pagenr] != NULL);
++sparsemem_pages;
-#endif
pages[pagenr] = page;

overlapped = true;
@@ -931,12 +909,10 @@ static int z_erofs_vle_unzip(struct super_block *sb,
if (err != -ENOTSUPP)
goto out_percpu;

-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
if (sparsemem_pages >= nr_pages) {
BUG_ON(sparsemem_pages > nr_pages);
goto skip_allocpage;
}
-#endif

for (i = 0; i < nr_pages; ++i) {
if (pages[i] != NULL)
@@ -945,9 +921,7 @@ static int z_erofs_vle_unzip(struct super_block *sb,
pages[i] = __stagingpage_alloc(page_pool, GFP_NOFS);
}

-#ifndef CONFIG_EROFS_FS_ZIP_MULTIREF
skip_allocpage:
-#endif
vout = erofs_vmap(pages, nr_pages);

err = z_erofs_vle_unzip_vmap(compressed_pages,
diff --git a/drivers/staging/erofs/unzip_vle.h b/drivers/staging/erofs/unzip_vle.h
index 3939985..3316bc3 100644
--- a/drivers/staging/erofs/unzip_vle.h
+++ b/drivers/staging/erofs/unzip_vle.h
@@ -47,13 +47,6 @@ static inline bool z_erofs_gather_if_stagingpage(struct list_head *page_pool,
#define Z_EROFS_VLE_INLINE_PAGEVECS 3

struct z_erofs_vle_work {
- /* struct z_erofs_vle_work *left, *right; */
-
-#ifdef CONFIG_EROFS_FS_ZIP_MULTIREF
- struct list_head list;
-
- atomic_t refcount;
-#endif
struct mutex lock;

/* I: decompression offset in page */
@@ -107,10 +100,8 @@ static inline void z_erofs_vle_set_workgrp_fmt(
grp->flags = fmt | (grp->flags & ~Z_EROFS_VLE_WORKGRP_FMT_MASK);
}

-#ifdef CONFIG_EROFS_FS_ZIP_MULTIREF
-#error multiref decompression is unimplemented yet
-#else

+/* definitions if multiref is disabled */
#define z_erofs_vle_grab_primary_work(grp) (&(grp)->work)
#define z_erofs_vle_grab_work(grp, pageofs) (&(grp)->work)
#define z_erofs_vle_work_workgroup(wrk, primary) \
@@ -118,7 +109,6 @@ static inline void z_erofs_vle_set_workgrp_fmt(
struct z_erofs_vle_workgroup, work) : \
({ BUG(); (void *)NULL; }))

-#endif

#define Z_EROFS_WORKGROUP_SIZE sizeof(struct z_erofs_vle_workgroup)

--
1.9.1
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