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Message-ID: <76f9241e-5e7b-1de4-6cef-c92aa1de7498@kernel.org>
Date: Wed, 4 Aug 2021 15:17:50 +0800
From: Chao Yu <chao@...nel.org>
To: Gao Xiang <hsiangkao@...ux.alibaba.com>,
linux-erofs@...ts.ozlabs.org
Cc: linux-fsdevel@...r.kernel.org, nvdimm@...ts.linux.dev,
LKML <linux-kernel@...r.kernel.org>,
"Darrick J. Wong" <djwong@...nel.org>,
Liu Bo <bo.liu@...ux.alibaba.com>,
Joseph Qi <joseph.qi@...ux.alibaba.com>,
Liu Jiang <gerry@...ux.alibaba.com>,
Huang Jianan <huangjianan@...o.com>,
Tao Ma <boyu.mt@...bao.com>
Subject: Re: [PATCH v2 3/3] erofs: convert all uncompressed cases to iomap
On 2021/7/31 3:46, Gao Xiang wrote:
> Since tail-packing inline has been supported by iomap now, let's
> convert all EROFS uncompressed data I/O to iomap, which is pretty
> straight-forward.
>
> Cc: linux-fsdevel@...r.kernel.org
> Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
> ---
> fs/erofs/data.c | 288 ++++++++----------------------------------------
> 1 file changed, 49 insertions(+), 239 deletions(-)
>
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index 911521293b20..6b98156bb5ca 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -9,29 +9,6 @@
> #include <linux/dax.h>
> #include <trace/events/erofs.h>
>
> -static void erofs_readendio(struct bio *bio)
> -{
> - struct bio_vec *bvec;
> - blk_status_t err = bio->bi_status;
> - struct bvec_iter_all iter_all;
> -
> - bio_for_each_segment_all(bvec, bio, iter_all) {
> - struct page *page = bvec->bv_page;
> -
> - /* page is already locked */
> - DBG_BUGON(PageUptodate(page));
> -
> - if (err)
> - SetPageError(page);
> - else
> - SetPageUptodate(page);
> -
> - unlock_page(page);
> - /* page could be reclaimed now */
> - }
> - bio_put(bio);
> -}
> -
> struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr)
> {
> struct address_space *const mapping = sb->s_bdev->bd_inode->i_mapping;
> @@ -109,206 +86,6 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
> return err;
> }
>
> -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,
> - unsigned int *eblks,
> - 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 &&
> - (*last_block + 1 != current_block || !*eblks)) {
> -submit_bio_retry:
> - submit_bio(bio);
> - 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_flatmode(inode, &map, EROFS_GET_BLOCKS_RAW);
> - if (err)
> - goto err_out;
> -
> - /* zero out the holed page */
> - if (!(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);
> -
> - 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);
> -
> - *eblks = bio_max_segs(nblocks);
> - bio = bio_alloc(GFP_NOIO, *eblks);
> -
> - bio->bi_end_io = erofs_readendio;
> - bio_set_dev(bio, sb->s_bdev);
> - bio->bi_iter.bi_sector = (sector_t)blknr <<
> - LOG_SECTORS_PER_BLOCK;
> - bio->bi_opf = REQ_OP_READ | (ra ? REQ_RAHEAD : 0);
> - }
> -
> - 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;
> - --*eblks;
> - *last_block = current_block;
> - 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(bio);
> - return 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;
> - unsigned int eblks;
> - struct bio *bio;
> -
> - trace_erofs_readpage(page, true);
> -
> - bio = erofs_read_raw_page(NULL, page->mapping,
> - page, &last_block, 1, &eblks, false);
> -
> - if (IS_ERR(bio))
> - return PTR_ERR(bio);
> -
> - if (bio)
> - submit_bio(bio);
> - return 0;
> -}
> -
> -static void erofs_raw_access_readahead(struct readahead_control *rac)
> -{
> - erofs_off_t last_block;
> - unsigned int eblks;
> - struct bio *bio = NULL;
> - struct page *page;
> -
> - trace_erofs_readpages(rac->mapping->host, readahead_index(rac),
> - readahead_count(rac), true);
> -
> - while ((page = readahead_page(rac))) {
> - prefetchw(&page->flags);
> -
> - bio = erofs_read_raw_page(bio, rac->mapping, page, &last_block,
> - readahead_count(rac), &eblks, 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_I(rac->mapping->host)->nid);
> -
> - bio = NULL;
> - }
> -
> - put_page(page);
> - }
> -
> - if (bio)
> - submit_bio(bio);
> -}
> -
> -static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
> -{
> - struct inode *inode = mapping->host;
> - struct erofs_map_blocks map = {
> - .m_la = blknr_to_addr(block),
> - };
> -
> - if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE) {
> - erofs_blk_t blks = i_size_read(inode) >> LOG_BLOCK_SIZE;
> -
> - if (block >> LOG_SECTORS_PER_BLOCK >= blks)
> - return 0;
> - }
> -
> - if (!erofs_map_blocks_flatmode(inode, &map, EROFS_GET_BLOCKS_RAW))
> - return erofs_blknr(map.m_pa);
> -
> - return 0;
> -}
> -
> static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
> {
> @@ -327,6 +104,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> iomap->offset = map.m_la;
> iomap->length = map.m_llen;
> iomap->flags = 0;
> + iomap->private = NULL;
>
> if (!(map.m_flags & EROFS_MAP_MAPPED)) {
> iomap->type = IOMAP_HOLE;
> @@ -336,20 +114,61 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> return 0;
> }
>
> - /* that shouldn't happen for now */
> if (map.m_flags & EROFS_MAP_META) {
> - DBG_BUGON(1);
> - return -ENOTBLK;
> + struct page *ipage;
> +
> + iomap->type = IOMAP_INLINE;
> + ipage = erofs_get_meta_page(inode->i_sb,
> + erofs_blknr(map.m_pa));
Error handling for erofs_get_meta_page()?
Thanks
> + iomap->inline_data = page_address(ipage) +
> + erofs_blkoff(map.m_pa);
> + iomap->private = ipage;
> + } else {
> + iomap->type = IOMAP_MAPPED;
> + iomap->addr = map.m_pa;
> }
> - iomap->type = IOMAP_MAPPED;
> - iomap->addr = map.m_pa;
> return 0;
> }
>
> +static int erofs_iomap_end(struct inode *inode, loff_t pos, loff_t length,
> + ssize_t written, unsigned flags, struct iomap *iomap)
> +{
> + struct page *ipage = iomap->private;
> +
> + if (ipage) {
> + DBG_BUGON(iomap->type != IOMAP_INLINE);
> + unlock_page(ipage);
> + put_page(ipage);
> + } else {
> + DBG_BUGON(iomap->type == IOMAP_INLINE);
> + }
> + return written;
> +}
> +
> const struct iomap_ops erofs_iomap_ops = {
> .iomap_begin = erofs_iomap_begin,
> + .iomap_end = erofs_iomap_end,
> };
>
> +/*
> + * since we dont have write or truncate flows, so no inode
> + * locking needs to be held at the moment.
> + */
> +static int erofs_readpage(struct file *file, struct page *page)
> +{
> + return iomap_readpage(page, &erofs_iomap_ops);
> +}
> +
> +static void erofs_readahead(struct readahead_control *rac)
> +{
> + return iomap_readahead(rac, &erofs_iomap_ops);
> +}
> +
> +static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
> +{
> + return iomap_bmap(mapping, block, &erofs_iomap_ops);
> +}
> +
> static int erofs_prepare_dio(struct kiocb *iocb, struct iov_iter *to)
> {
> struct inode *inode = file_inode(iocb->ki_filp);
> @@ -365,15 +184,6 @@ static int erofs_prepare_dio(struct kiocb *iocb, struct iov_iter *to)
>
> if (align & blksize_mask)
> return -EINVAL;
> -
> - /*
> - * Temporarily fall back tail-packing inline to buffered I/O instead
> - * since tail-packing inline support relies on an iomap core update.
> - */
> - if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE &&
> - iocb->ki_pos + iov_iter_count(to) >
> - rounddown(inode->i_size, EROFS_BLKSIZ))
> - return 1;
> return 0;
> }
>
> @@ -409,8 +219,8 @@ static ssize_t erofs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
>
> /* for uncompressed (aligned) files and raw access for other files */
> const struct address_space_operations erofs_raw_access_aops = {
> - .readpage = erofs_raw_access_readpage,
> - .readahead = erofs_raw_access_readahead,
> + .readpage = erofs_readpage,
> + .readahead = erofs_readahead,
> .bmap = erofs_bmap,
> .direct_IO = noop_direct_IO,
> };
>
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