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, 423 insertions, 0 deletions

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
new file mode 100644
index 000000000000..fda16ec8863e
--- /dev/null
+++ b/fs/erofs/data.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ *             http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#include "internal.h"
+#include <linux/prefetch.h>
+
+#include <trace/events/erofs.h>
+
+static inline void read_endio(struct bio *bio)
+{
+	struct super_block *const sb = bio->bi_private;
+	struct bio_vec *bvec;
+	blk_status_t err = bio->bi_status;
+	struct bvec_iter_all iter_all;
+
+	if (time_to_inject(EROFS_SB(sb), FAULT_READ_IO)) {
+		erofs_show_injection_info(FAULT_READ_IO);
+		err = BLK_STS_IOERR;
+	}
+
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		struct page *page = bvec->bv_page;
+
+		/* page is already locked */
+		DBG_BUGON(PageUptodate(page));
+
+		if (unlikely(err))
+			SetPageError(page);
+		else
+			SetPageUptodate(page);
+
+		unlock_page(page);
+		/* page could be reclaimed now */
+	}
+	bio_put(bio);
+}
+
+/* prio -- true is used for dir */
+struct page *__erofs_get_meta_page(struct super_block *sb,
+				   erofs_blk_t blkaddr, bool prio, bool nofail)
+{
+	struct inode *const bd_inode = sb->s_bdev->bd_inode;
+	struct address_space *const mapping = bd_inode->i_mapping;
+	/* prefer retrying in the allocator to blindly looping below */
+	const gfp_t gfp = mapping_gfp_constraint(mapping, ~__GFP_FS) |
+		(nofail ? __GFP_NOFAIL : 0);
+	unsigned int io_retries = nofail ? EROFS_IO_MAX_RETRIES_NOFAIL : 0;
+	struct page *page;
+	int err;
+
+repeat:
+	page = find_or_create_page(mapping, blkaddr, gfp);
+	if (unlikely(!page)) {
+		DBG_BUGON(nofail);
+		return ERR_PTR(-ENOMEM);
+	}
+	DBG_BUGON(!PageLocked(page));
+
+	if (!PageUptodate(page)) {
+		struct bio *bio;
+
+		bio = erofs_grab_bio(sb, blkaddr, 1, sb, read_endio, nofail);
+		if (IS_ERR(bio)) {
+			DBG_BUGON(nofail);
+			err = PTR_ERR(bio);
+			goto err_out;
+		}
+
+		err = bio_add_page(bio, page, PAGE_SIZE, 0);
+		if (unlikely(err != PAGE_SIZE)) {
+			err = -EFAULT;
+			goto err_out;
+		}
+
+		__submit_bio(bio, REQ_OP_READ,
+			     REQ_META | (prio ? REQ_PRIO : 0));
+
+		lock_page(page);
+
+		/* this page has been truncated by others */
+		if (unlikely(page->mapping != mapping)) {
+unlock_repeat:
+			unlock_page(page);
+			put_page(page);
+			goto repeat;
+		}
+
+		/* more likely a read error */
+		if (unlikely(!PageUptodate(page))) {
+			if (io_retries) {
+				--io_retries;
+				goto unlock_repeat;
+			}
+			err = -EIO;
+			goto err_out;
+		}
+	}
+	return page;
+
+err_out:
+	unlock_page(page);
+	put_page(page);
+	return ERR_PTR(err);
+}
+
+static int erofs_map_blocks_flatmode(struct inode *inode,
+				     struct erofs_map_blocks *map,
+				     int flags)
+{
+	int err = 0;
+	erofs_blk_t nblocks, lastblk;
+	u64 offset = map->m_la;
+	struct erofs_vnode *vi = EROFS_V(inode);
+
+	trace_erofs_map_blocks_flatmode_enter(inode, map, flags);
+
+	nblocks = DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
+	lastblk = nblocks - is_inode_flat_inline(inode);
+
+	if (unlikely(offset >= inode->i_size)) {
+		/* leave out-of-bound access unmapped */
+		map->m_flags = 0;
+		map->m_plen = 0;
+		goto out;
+	}
+
+	/* there is no hole in flatmode */
+	map->m_flags = EROFS_MAP_MAPPED;
+
+	if (offset < blknr_to_addr(lastblk)) {
+		map->m_pa = blknr_to_addr(vi->raw_blkaddr) + map->m_la;
+		map->m_plen = blknr_to_addr(lastblk) - offset;
+	} else if (is_inode_flat_inline(inode)) {
+		/* 2 - inode inline B: inode, [xattrs], inline last blk... */
+		struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
+
+		map->m_pa = iloc(sbi, vi->nid) + vi->inode_isize +
+			vi->xattr_isize + erofs_blkoff(map->m_la);
+		map->m_plen = inode->i_size - offset;
+
+		/* inline data should be located in one meta block */
+		if (erofs_blkoff(map->m_pa) + map->m_plen > PAGE_SIZE) {
+			errln("inline data cross block boundary @ nid %llu",
+			      vi->nid);
+			DBG_BUGON(1);
+			err = -EFSCORRUPTED;
+			goto err_out;
+		}
+
+		map->m_flags |= EROFS_MAP_META;
+	} else {
+		errln("internal error @ nid: %llu (size %llu), m_la 0x%llx",
+		      vi->nid, inode->i_size, map->m_la);
+		DBG_BUGON(1);
+		err = -EIO;
+		goto err_out;
+	}
+
+out:
+	map->m_llen = map->m_plen;
+
+err_out:
+	trace_erofs_map_blocks_flatmode_exit(inode, map, flags, 0);
+	return err;
+}
+
+int erofs_map_blocks(struct inode *inode,
+		     struct erofs_map_blocks *map, int flags)
+{
+	if (unlikely(is_inode_layout_compression(inode))) {
+		int err = z_erofs_map_blocks_iter(inode, map, flags);
+
+		if (map->mpage) {
+			put_page(map->mpage);
+			map->mpage = NULL;
+		}
+		return err;
+	}
+	return erofs_map_blocks_flatmode(inode, map, flags);
+}
+
+static inline struct bio *erofs_read_raw_page(struct bio *bio,
+					      struct address_space *mapping,
+					      struct page *page,
+					      erofs_off_t *last_block,
+					      unsigned int nblocks,
+					      bool ra)
+{
+	struct inode *const inode = mapping->host;
+	struct super_block *const sb = inode->i_sb;
+	erofs_off_t current_block = (erofs_off_t)page->index;
+	int err;
+
+	DBG_BUGON(!nblocks);
+
+	if (PageUptodate(page)) {
+		err = 0;
+		goto has_updated;
+	}
+
+	/* note that for readpage case, bio also equals to NULL */
+	if (bio &&
+	    /* not continuous */
+	    *last_block + 1 != current_block) {
+submit_bio_retry:
+		__submit_bio(bio, REQ_OP_READ, 0);
+		bio = NULL;
+	}
+
+	if (!bio) {
+		struct erofs_map_blocks map = {
+			.m_la = blknr_to_addr(current_block),
+		};
+		erofs_blk_t blknr;
+		unsigned int blkoff;
+
+		err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
+		if (unlikely(err))
+			goto err_out;
+
+		/* zero out the holed page */
+		if (unlikely(!(map.m_flags & EROFS_MAP_MAPPED))) {
+			zero_user_segment(page, 0, PAGE_SIZE);
+			SetPageUptodate(page);
+
+			/* imply err = 0, see erofs_map_blocks */
+			goto has_updated;
+		}
+
+		/* for RAW access mode, m_plen must be equal to m_llen */
+		DBG_BUGON(map.m_plen != map.m_llen);
+
+		blknr = erofs_blknr(map.m_pa);
+		blkoff = erofs_blkoff(map.m_pa);
+
+		/* deal with inline page */
+		if (map.m_flags & EROFS_MAP_META) {
+			void *vsrc, *vto;
+			struct page *ipage;
+
+			DBG_BUGON(map.m_plen > PAGE_SIZE);
+
+			ipage = erofs_get_meta_page(inode->i_sb, blknr, 0);
+
+			if (IS_ERR(ipage)) {
+				err = PTR_ERR(ipage);
+				goto err_out;
+			}
+
+			vsrc = kmap_atomic(ipage);
+			vto = kmap_atomic(page);
+			memcpy(vto, vsrc + blkoff, map.m_plen);
+			memset(vto + map.m_plen, 0, PAGE_SIZE - map.m_plen);
+			kunmap_atomic(vto);
+			kunmap_atomic(vsrc);
+			flush_dcache_page(page);
+
+			SetPageUptodate(page);
+			/* TODO: could we unlock the page earlier? */
+			unlock_page(ipage);
+			put_page(ipage);
+
+			/* imply err = 0, see erofs_map_blocks */
+			goto has_updated;
+		}
+
+		/* pa must be block-aligned for raw reading */
+		DBG_BUGON(erofs_blkoff(map.m_pa));
+
+		/* max # of continuous pages */
+		if (nblocks > DIV_ROUND_UP(map.m_plen, PAGE_SIZE))
+			nblocks = DIV_ROUND_UP(map.m_plen, PAGE_SIZE);
+		if (nblocks > BIO_MAX_PAGES)
+			nblocks = BIO_MAX_PAGES;
+
+		bio = erofs_grab_bio(sb, blknr, nblocks, sb,
+				     read_endio, false);
+		if (IS_ERR(bio)) {
+			err = PTR_ERR(bio);
+			bio = NULL;
+			goto err_out;
+		}
+	}
+
+	err = bio_add_page(bio, page, PAGE_SIZE, 0);
+	/* out of the extent or bio is full */
+	if (err < PAGE_SIZE)
+		goto submit_bio_retry;
+
+	*last_block = current_block;
+
+	/* shift in advance in case of it followed by too many gaps */
+	if (bio->bi_iter.bi_size >= bio->bi_max_vecs * PAGE_SIZE) {
+		/* err should reassign to 0 after submitting */
+		err = 0;
+		goto submit_bio_out;
+	}
+
+	return bio;
+
+err_out:
+	/* for sync reading, set page error immediately */
+	if (!ra) {
+		SetPageError(page);
+		ClearPageUptodate(page);
+	}
+has_updated:
+	unlock_page(page);
+
+	/* if updated manually, continuous pages has a gap */
+	if (bio)
+submit_bio_out:
+		__submit_bio(bio, REQ_OP_READ, 0);
+
+	return unlikely(err) ? ERR_PTR(err) : NULL;
+}
+
+/*
+ * since we dont have write or truncate flows, so no inode
+ * locking needs to be held at the moment.
+ */
+static int erofs_raw_access_readpage(struct file *file, struct page *page)
+{
+	erofs_off_t last_block;
+	struct bio *bio;
+
+	trace_erofs_readpage(page, true);
+
+	bio = erofs_read_raw_page(NULL, page->mapping,
+				  page, &last_block, 1, false);
+
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	DBG_BUGON(bio);	/* since we have only one bio -- must be NULL */
+	return 0;
+}
+
+static int erofs_raw_access_readpages(struct file *filp,
+				      struct address_space *mapping,
+				      struct list_head *pages,
+				      unsigned int nr_pages)
+{
+	erofs_off_t last_block;
+	struct bio *bio = NULL;
+	gfp_t gfp = readahead_gfp_mask(mapping);
+	struct page *page = list_last_entry(pages, struct page, lru);
+
+	trace_erofs_readpages(mapping->host, page, nr_pages, true);
+
+	for (; nr_pages; --nr_pages) {
+		page = list_entry(pages->prev, struct page, lru);
+
+		prefetchw(&page->flags);
+		list_del(&page->lru);
+
+		if (!add_to_page_cache_lru(page, mapping, page->index, gfp)) {
+			bio = erofs_read_raw_page(bio, mapping, page,
+						  &last_block, nr_pages, true);
+
+			/* all the page errors are ignored when readahead */
+			if (IS_ERR(bio)) {
+				pr_err("%s, readahead error at page %lu of nid %llu\n",
+				       __func__, page->index,
+				       EROFS_V(mapping->host)->nid);
+
+				bio = NULL;
+			}
+		}
+
+		/* pages could still be locked */
+		put_page(page);
+	}
+	DBG_BUGON(!list_empty(pages));
+
+	/* the rare case (end in gaps) */
+	if (unlikely(bio))
+		__submit_bio(bio, REQ_OP_READ, 0);
+	return 0;
+}
+
+static int erofs_get_block(struct inode *inode, sector_t iblock,
+			   struct buffer_head *bh, int create)
+{
+	struct erofs_map_blocks map = {
+		.m_la = iblock << 9,
+	};
+	int err;
+
+	err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
+	if (err)
+		return err;
+
+	if (map.m_flags & EROFS_MAP_MAPPED)
+		bh->b_blocknr = erofs_blknr(map.m_pa);
+
+	return err;
+}
+
+static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
+{
+	struct inode *inode = mapping->host;
+
+	if (is_inode_flat_inline(inode)) {
+		erofs_blk_t blks = i_size_read(inode) >> LOG_BLOCK_SIZE;
+
+		if (block >> LOG_SECTORS_PER_BLOCK >= blks)
+			return 0;
+	}
+
+	return generic_block_bmap(mapping, block, erofs_get_block);
+}
+
+/* for uncompressed (aligned) files and raw access for other files */
+const struct address_space_operations erofs_raw_access_aops = {
+	.readpage = erofs_raw_access_readpage,
+	.readpages = erofs_raw_access_readpages,
+	.bmap = erofs_bmap,
+};
+