erofs: move erofs out of staging

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>

1 files changed, 157 insertions, 0 deletions

diff --git a/fs/erofs/zpvec.h b/fs/erofs/zpvec.h
new file mode 100644
index 000000000000..bd3cee16491c
--- /dev/null
+++ b/fs/erofs/zpvec.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2018 HUAWEI, Inc.
+ *             http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@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 *occupied)
+{
+        *occupied = false;
+        if (unlikely(!ctor->next && type))
+                if (ctor->index + 1 == ctor->nr)
+                        return false;
+
+        if (unlikely(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;
+                *occupied = true;
+        }
+        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 (unlikely(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
+