From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:53674 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933834AbeEIHud (ORCPT ); Wed, 9 May 2018 03:50:33 -0400 From: Christoph Hellwig To: linux-xfs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 30/33] iomap: add initial support for writes without buffer heads Date: Wed, 9 May 2018 09:48:27 +0200 Message-Id: <20180509074830.16196-31-hch@lst.de> In-Reply-To: <20180509074830.16196-1-hch@lst.de> References: <20180509074830.16196-1-hch@lst.de> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org For now just limited to blocksize == PAGE_SIZE, where we can simply read in the full page in write begin, and just set the whole page dirty after copying data into it. This code is enabled by default and XFS will now be feed pages without buffer heads in ->writepage and ->writepages. Signed-off-by: Christoph Hellwig --- fs/iomap.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 120 insertions(+), 9 deletions(-) diff --git a/fs/iomap.c b/fs/iomap.c index 967bd31540fe..a3861945504f 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -308,6 +308,56 @@ iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) truncate_pagecache_range(inode, max(pos, i_size), pos + len); } +static int +iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page, + unsigned poff, unsigned plen, struct iomap *iomap) +{ + struct bio_vec bvec; + struct bio bio; + int ret; + + bio_init(&bio, &bvec, 1); + bio.bi_opf = REQ_OP_READ; + bio.bi_iter.bi_sector = iomap_sector(iomap, block_start); + bio_set_dev(&bio, iomap->bdev); + __bio_add_page(&bio, page, plen, poff); + ret = submit_bio_wait(&bio); + if (ret < 0 && iomap_block_needs_zeroing(inode, block_start, iomap)) + zero_user(page, poff, plen); + return ret; +} + +static int +__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, + struct page *page, struct iomap *iomap) +{ + loff_t block_size = i_blocksize(inode); + loff_t block_start = pos & ~(block_size - 1); + loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1); + unsigned poff = block_start & (PAGE_SIZE - 1); + unsigned plen = min_t(loff_t, PAGE_SIZE - poff, block_end - block_start); + int status; + + if (PageUptodate(page)) + return 0; + + if (iomap_block_needs_zeroing(inode, block_start, iomap)) { + unsigned from = pos & (PAGE_SIZE - 1), to = from + len; + unsigned pend = poff + plen; + + if (poff < from || pend > to) + zero_user_segments(page, poff, from, to, pend); + } else { + status = iomap_read_page_sync(inode, block_start, page, + poff, plen, iomap); + if (status < 0) + return status; + SetPageUptodate(page); + } + + return 0; +} + static int iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, struct page **pagep, struct iomap *iomap) @@ -325,7 +375,10 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, if (!page) return -ENOMEM; - status = __block_write_begin_int(page, pos, len, NULL, iomap); + if (i_blocksize(inode) == PAGE_SIZE) + status = __iomap_write_begin(inode, pos, len, page, iomap); + else + status = __block_write_begin_int(page, pos, len, NULL, iomap); if (unlikely(status)) { unlock_page(page); put_page(page); @@ -338,12 +391,63 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, return status; } +static int +iomap_set_page_dirty(struct page *page) +{ + struct address_space *mapping = page_mapping(page); + int newly_dirty; + + if (unlikely(!mapping)) + return !TestSetPageDirty(page); + + /* + * Lock out page->mem_cgroup migration to keep PageDirty + * synchronized with per-memcg dirty page counters. + */ + lock_page_memcg(page); + newly_dirty = !TestSetPageDirty(page); + if (newly_dirty) + __set_page_dirty(page, mapping, 0); + unlock_page_memcg(page); + + if (newly_dirty) + __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); + return newly_dirty; +} + +static int +__iomap_write_end(struct inode *inode, loff_t pos, unsigned len, + unsigned copied, struct page *page, struct iomap *iomap) +{ + unsigned start = pos & (PAGE_SIZE - 1); + int ret; + + if (unlikely(copied < len)) { + /* see block_write_end() for an explanation */ + if (!PageUptodate(page)) + copied = 0; + if (iomap_block_needs_zeroing(inode, pos, iomap)) + zero_user(page, start + copied, len - copied); + } + + flush_dcache_page(page); + SetPageUptodate(page); + iomap_set_page_dirty(page); + ret = __generic_write_end(inode, pos, copied, page); + if (ret < len) + iomap_write_failed(inode, pos, len); + return ret; +} + static int iomap_write_end(struct inode *inode, loff_t pos, unsigned len, - unsigned copied, struct page *page) + unsigned copied, struct page *page, struct iomap *iomap) { int ret; + if (i_blocksize(inode) == PAGE_SIZE) + return __iomap_write_end(inode, pos, len, copied, page, iomap); + ret = generic_write_end(NULL, inode->i_mapping, pos, len, copied, page, NULL); if (ret < len) @@ -400,7 +504,8 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, flush_dcache_page(page); - status = iomap_write_end(inode, pos, bytes, copied, page); + status = iomap_write_end(inode, pos, bytes, copied, page, + iomap); if (unlikely(status < 0)) break; copied = status; @@ -494,7 +599,7 @@ iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data, WARN_ON_ONCE(!PageUptodate(page)); - status = iomap_write_end(inode, pos, bytes, bytes, page); + status = iomap_write_end(inode, pos, bytes, bytes, page, iomap); if (unlikely(status <= 0)) { if (WARN_ON_ONCE(status == 0)) return -EIO; @@ -546,7 +651,7 @@ static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, zero_user(page, offset, bytes); mark_page_accessed(page); - return iomap_write_end(inode, pos, bytes, bytes, page); + return iomap_write_end(inode, pos, bytes, bytes, page, iomap); } static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes, @@ -632,11 +737,14 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, struct page *page = data; int ret; - ret = __block_write_begin_int(page, pos, length, NULL, iomap); - if (ret) - return ret; + if (i_blocksize(inode) != PAGE_SIZE) { + ret = __block_write_begin_int(page, pos, length, NULL, iomap); + if (ret) + return ret; + + block_commit_write(page, 0, length); + } - block_commit_write(page, 0, length); return length; } @@ -663,6 +771,9 @@ int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) else length = PAGE_SIZE; + if (i_blocksize(inode) == PAGE_SIZE) + WARN_ON_ONCE(!PageUptodate(page)); + offset = page_offset(page); while (length > 0) { ret = iomap_apply(inode, offset, length, -- 2.17.0