From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: iomap: convert from readpages to readahead Use the new readahead operation in iomap. Convert XFS and ZoneFS to use it. Link: http://lkml.kernel.org/r/20200414150233.24495-26-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx> Cc: Chao Yu <yuchao0@xxxxxxxxxx> Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx> Cc: Dave Chinner <dchinner@xxxxxxxxxx> Cc: Eric Biggers <ebiggers@xxxxxxxxxx> Cc: Gao Xiang <gaoxiang25@xxxxxxxxxx> Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Cc: John Hubbard <jhubbard@xxxxxxxxxx> Cc: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Zi Yan <ziy@xxxxxxxxxx> Cc: Johannes Thumshirn <johannes.thumshirn@xxxxxxx> Cc: Miklos Szeredi <mszeredi@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/iomap/buffered-io.c | 92 +++++++++++++-------------------------- fs/iomap/trace.h | 2 fs/xfs/xfs_aops.c | 13 ++--- fs/zonefs/super.c | 7 +- include/linux/iomap.h | 3 - 5 files changed, 42 insertions(+), 75 deletions(-) --- a/fs/iomap/buffered-io.c~iomap-convert-from-readpages-to-readahead +++ a/fs/iomap/buffered-io.c @@ -214,9 +214,8 @@ iomap_read_end_io(struct bio *bio) struct iomap_readpage_ctx { struct page *cur_page; bool cur_page_in_bio; - bool is_readahead; struct bio *bio; - struct list_head *pages; + struct readahead_control *rac; }; static void @@ -308,7 +307,7 @@ iomap_readpage_actor(struct inode *inode if (ctx->bio) submit_bio(ctx->bio); - if (ctx->is_readahead) /* same as readahead_gfp_mask */ + if (ctx->rac) /* same as readahead_gfp_mask */ gfp |= __GFP_NORETRY | __GFP_NOWARN; ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs)); /* @@ -319,7 +318,7 @@ iomap_readpage_actor(struct inode *inode if (!ctx->bio) ctx->bio = bio_alloc(orig_gfp, 1); ctx->bio->bi_opf = REQ_OP_READ; - if (ctx->is_readahead) + if (ctx->rac) ctx->bio->bi_opf |= REQ_RAHEAD; ctx->bio->bi_iter.bi_sector = sector; bio_set_dev(ctx->bio, iomap->bdev); @@ -375,36 +374,8 @@ iomap_readpage(struct page *page, const } EXPORT_SYMBOL_GPL(iomap_readpage); -static struct page * -iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos, - loff_t length, loff_t *done) -{ - while (!list_empty(pages)) { - struct page *page = lru_to_page(pages); - - if (page_offset(page) >= (u64)pos + length) - break; - - list_del(&page->lru); - if (!add_to_page_cache_lru(page, inode->i_mapping, page->index, - GFP_NOFS)) - return page; - - /* - * If we already have a page in the page cache at index we are - * done. Upper layers don't care if it is uptodate after the - * readpages call itself as every page gets checked again once - * actually needed. - */ - *done += PAGE_SIZE; - put_page(page); - } - - return NULL; -} - static loff_t -iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length, +iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap, struct iomap *srcmap) { struct iomap_readpage_ctx *ctx = data; @@ -418,10 +389,7 @@ iomap_readpages_actor(struct inode *inod ctx->cur_page = NULL; } if (!ctx->cur_page) { - ctx->cur_page = iomap_next_page(inode, ctx->pages, - pos, length, &done); - if (!ctx->cur_page) - break; + ctx->cur_page = readahead_page(ctx->rac); ctx->cur_page_in_bio = false; } ret = iomap_readpage_actor(inode, pos + done, length - done, @@ -431,32 +399,43 @@ iomap_readpages_actor(struct inode *inod return done; } -int -iomap_readpages(struct address_space *mapping, struct list_head *pages, - unsigned nr_pages, const struct iomap_ops *ops) -{ +/** + * iomap_readahead - Attempt to read pages from a file. + * @rac: Describes the pages to be read. + * @ops: The operations vector for the filesystem. + * + * This function is for filesystems to call to implement their readahead + * address_space operation. + * + * Context: The @ops callbacks may submit I/O (eg to read the addresses of + * blocks from disc), and may wait for it. The caller may be trying to + * access a different page, and so sleeping excessively should be avoided. + * It may allocate memory, but should avoid costly allocations. This + * function is called with memalloc_nofs set, so allocations will not cause + * the filesystem to be reentered. + */ +void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops) +{ + struct inode *inode = rac->mapping->host; + loff_t pos = readahead_pos(rac); + loff_t length = readahead_length(rac); struct iomap_readpage_ctx ctx = { - .pages = pages, - .is_readahead = true, + .rac = rac, }; - loff_t pos = page_offset(list_entry(pages->prev, struct page, lru)); - loff_t last = page_offset(list_entry(pages->next, struct page, lru)); - loff_t length = last - pos + PAGE_SIZE, ret = 0; - trace_iomap_readpages(mapping->host, nr_pages); + trace_iomap_readahead(inode, readahead_count(rac)); while (length > 0) { - ret = iomap_apply(mapping->host, pos, length, 0, ops, - &ctx, iomap_readpages_actor); + loff_t ret = iomap_apply(inode, pos, length, 0, ops, + &ctx, iomap_readahead_actor); if (ret <= 0) { WARN_ON_ONCE(ret == 0); - goto done; + break; } pos += ret; length -= ret; } - ret = 0; -done: + if (ctx.bio) submit_bio(ctx.bio); if (ctx.cur_page) { @@ -464,15 +443,8 @@ done: unlock_page(ctx.cur_page); put_page(ctx.cur_page); } - - /* - * Check that we didn't lose a page due to the arcance calling - * conventions.. - */ - WARN_ON_ONCE(!ret && !list_empty(ctx.pages)); - return ret; } -EXPORT_SYMBOL_GPL(iomap_readpages); +EXPORT_SYMBOL_GPL(iomap_readahead); /* * iomap_is_partially_uptodate checks whether blocks within a page are --- a/fs/iomap/trace.h~iomap-convert-from-readpages-to-readahead +++ a/fs/iomap/trace.h @@ -39,7 +39,7 @@ DEFINE_EVENT(iomap_readpage_class, name, TP_PROTO(struct inode *inode, int nr_pages), \ TP_ARGS(inode, nr_pages)) DEFINE_READPAGE_EVENT(iomap_readpage); -DEFINE_READPAGE_EVENT(iomap_readpages); +DEFINE_READPAGE_EVENT(iomap_readahead); DECLARE_EVENT_CLASS(iomap_range_class, TP_PROTO(struct inode *inode, unsigned long off, unsigned int len), --- a/fs/xfs/xfs_aops.c~iomap-convert-from-readpages-to-readahead +++ a/fs/xfs/xfs_aops.c @@ -621,14 +621,11 @@ xfs_vm_readpage( return iomap_readpage(page, &xfs_read_iomap_ops); } -STATIC int -xfs_vm_readpages( - struct file *unused, - struct address_space *mapping, - struct list_head *pages, - unsigned nr_pages) +STATIC void +xfs_vm_readahead( + struct readahead_control *rac) { - return iomap_readpages(mapping, pages, nr_pages, &xfs_read_iomap_ops); + iomap_readahead(rac, &xfs_read_iomap_ops); } static int @@ -644,7 +641,7 @@ xfs_iomap_swapfile_activate( const struct address_space_operations xfs_address_space_operations = { .readpage = xfs_vm_readpage, - .readpages = xfs_vm_readpages, + .readahead = xfs_vm_readahead, .writepage = xfs_vm_writepage, .writepages = xfs_vm_writepages, .set_page_dirty = iomap_set_page_dirty, --- a/fs/zonefs/super.c~iomap-convert-from-readpages-to-readahead +++ a/fs/zonefs/super.c @@ -78,10 +78,9 @@ static int zonefs_readpage(struct file * return iomap_readpage(page, &zonefs_iomap_ops); } -static int zonefs_readpages(struct file *unused, struct address_space *mapping, - struct list_head *pages, unsigned int nr_pages) +static void zonefs_readahead(struct readahead_control *rac) { - return iomap_readpages(mapping, pages, nr_pages, &zonefs_iomap_ops); + iomap_readahead(rac, &zonefs_iomap_ops); } /* @@ -128,7 +127,7 @@ static int zonefs_writepages(struct addr static const struct address_space_operations zonefs_file_aops = { .readpage = zonefs_readpage, - .readpages = zonefs_readpages, + .readahead = zonefs_readahead, .writepage = zonefs_writepage, .writepages = zonefs_writepages, .set_page_dirty = iomap_set_page_dirty, --- a/include/linux/iomap.h~iomap-convert-from-readpages-to-readahead +++ a/include/linux/iomap.h @@ -155,8 +155,7 @@ loff_t iomap_apply(struct inode *inode, ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from, const struct iomap_ops *ops); int iomap_readpage(struct page *page, const struct iomap_ops *ops); -int iomap_readpages(struct address_space *mapping, struct list_head *pages, - unsigned nr_pages, const struct iomap_ops *ops); +void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops); int iomap_set_page_dirty(struct page *page); int iomap_is_partially_uptodate(struct page *page, unsigned long from, unsigned long count); _
