From patchwork Sun Sep 1 20:08:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 11125669 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A315D1510 for ; Sun, 1 Sep 2019 20:09:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7904622CF7 for ; Sun, 1 Sep 2019 20:09:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729012AbfIAUJE (ORCPT ); Sun, 1 Sep 2019 16:09:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:50518 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728973AbfIAUJD (ORCPT ); Sun, 1 Sep 2019 16:09:03 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id ABCF5B626; Sun, 1 Sep 2019 20:09:01 +0000 (UTC) From: Goldwyn Rodrigues To: linux-fsdevel@vger.kernel.org Cc: linux-btrfs@vger.kernel.org, darrick.wong@oracle.com, hch@lst.de, david@fromorbit.com, riteshh@linux.ibm.com, Goldwyn Rodrigues Subject: [PATCH 07/15] btrfs: remove buffered write code made unnecessary Date: Sun, 1 Sep 2019 15:08:28 -0500 Message-Id: <20190901200836.14959-8-rgoldwyn@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190901200836.14959-1-rgoldwyn@suse.de> References: <20190901200836.14959-1-rgoldwyn@suse.de> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Goldwyn Rodrigues Better done in a separate patch to keep the main patch short(er) Signed-off-by: Goldwyn Rodrigues --- fs/btrfs/file.c | 463 -------------------------------------------------------- 1 file changed, 463 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 0707db04d3cc..f7087e28ac08 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -390,79 +390,6 @@ int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info) return 0; } -/* simple helper to fault in pages and copy. This should go away - * and be replaced with calls into generic code. - */ -static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes, - struct page **prepared_pages, - struct iov_iter *i) -{ - size_t copied = 0; - size_t total_copied = 0; - int pg = 0; - int offset = offset_in_page(pos); - - while (write_bytes > 0) { - size_t count = min_t(size_t, - PAGE_SIZE - offset, write_bytes); - struct page *page = prepared_pages[pg]; - /* - * Copy data from userspace to the current page - */ - copied = iov_iter_copy_from_user_atomic(page, i, offset, count); - - /* Flush processor's dcache for this page */ - flush_dcache_page(page); - - /* - * if we get a partial write, we can end up with - * partially up to date pages. These add - * a lot of complexity, so make sure they don't - * happen by forcing this copy to be retried. - * - * The rest of the btrfs_file_write code will fall - * back to page at a time copies after we return 0. - */ - if (!PageUptodate(page) && copied < count) - copied = 0; - - iov_iter_advance(i, copied); - write_bytes -= copied; - total_copied += copied; - - /* Return to btrfs_file_write_iter to fault page */ - if (unlikely(copied == 0)) - break; - - if (copied < PAGE_SIZE - offset) { - offset += copied; - } else { - pg++; - offset = 0; - } - } - return total_copied; -} - -/* - * unlocks pages after btrfs_file_write is done with them - */ -static void btrfs_drop_pages(struct page **pages, size_t num_pages) -{ - size_t i; - for (i = 0; i < num_pages; i++) { - /* page checked is some magic around finding pages that - * have been modified without going through btrfs_set_page_dirty - * clear it here. There should be no need to mark the pages - * accessed as prepare_pages should have marked them accessed - * in prepare_pages via find_or_create_page() - */ - ClearPageChecked(pages[i]); - unlock_page(pages[i]); - put_page(pages[i]); - } -} - static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode, const u64 start, const u64 len, @@ -1387,164 +1314,6 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans, return 0; } -/* - * on error we return an unlocked page and the error value - * on success we return a locked page and 0 - */ -static int prepare_uptodate_page(struct inode *inode, - struct page *page, u64 pos, - bool force_uptodate) -{ - int ret = 0; - - if (((pos & (PAGE_SIZE - 1)) || force_uptodate) && - !PageUptodate(page)) { - ret = btrfs_readpage(NULL, page); - if (ret) - return ret; - lock_page(page); - if (!PageUptodate(page)) { - unlock_page(page); - return -EIO; - } - if (page->mapping != inode->i_mapping) { - unlock_page(page); - return -EAGAIN; - } - } - return 0; -} - -/* - * this just gets pages into the page cache and locks them down. - */ -static noinline int prepare_pages(struct inode *inode, struct page **pages, - size_t num_pages, loff_t pos, - size_t write_bytes, bool force_uptodate) -{ - int i; - unsigned long index = pos >> PAGE_SHIFT; - gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping); - int err = 0; - int faili; - - for (i = 0; i < num_pages; i++) { -again: - pages[i] = find_or_create_page(inode->i_mapping, index + i, - mask | __GFP_WRITE); - if (!pages[i]) { - faili = i - 1; - err = -ENOMEM; - goto fail; - } - - if (i == 0) - err = prepare_uptodate_page(inode, pages[i], pos, - force_uptodate); - if (!err && i == num_pages - 1) - err = prepare_uptodate_page(inode, pages[i], - pos + write_bytes, false); - if (err) { - put_page(pages[i]); - if (err == -EAGAIN) { - err = 0; - goto again; - } - faili = i - 1; - goto fail; - } - wait_on_page_writeback(pages[i]); - } - - return 0; -fail: - while (faili >= 0) { - unlock_page(pages[faili]); - put_page(pages[faili]); - faili--; - } - return err; - -} - -/* - * This function locks the extent and properly waits for data=ordered extents - * to finish before allowing the pages to be modified if need. - * - * The return value: - * 1 - the extent is locked - * 0 - the extent is not locked, and everything is OK - * -EAGAIN - need re-prepare the pages - * the other < 0 number - Something wrong happens - */ -static noinline int -lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages, - size_t num_pages, loff_t pos, - size_t write_bytes, - u64 *lockstart, u64 *lockend, - struct extent_state **cached_state) -{ - struct btrfs_fs_info *fs_info = inode->root->fs_info; - u64 start_pos; - u64 last_pos; - int i; - int ret = 0; - - start_pos = round_down(pos, fs_info->sectorsize); - last_pos = start_pos - + round_up(pos + write_bytes - start_pos, - fs_info->sectorsize) - 1; - - if (start_pos < inode->vfs_inode.i_size) { - struct btrfs_ordered_extent *ordered; - - lock_extent_bits(&inode->io_tree, start_pos, last_pos, - cached_state); - ordered = btrfs_lookup_ordered_range(inode, start_pos, - last_pos - start_pos + 1); - if (ordered && - ordered->file_offset + ordered->len > start_pos && - ordered->file_offset <= last_pos) { - unlock_extent_cached(&inode->io_tree, start_pos, - last_pos, cached_state); - for (i = 0; i < num_pages; i++) { - unlock_page(pages[i]); - put_page(pages[i]); - } - btrfs_start_ordered_extent(&inode->vfs_inode, - ordered, 1); - btrfs_put_ordered_extent(ordered); - return -EAGAIN; - } - if (ordered) - btrfs_put_ordered_extent(ordered); - - *lockstart = start_pos; - *lockend = last_pos; - ret = 1; - } - - /* - * It's possible the pages are dirty right now, but we don't want - * to clean them yet because copy_from_user may catch a page fault - * and we might have to fall back to one page at a time. If that - * happens, we'll unlock these pages and we'd have a window where - * reclaim could sneak in and drop the once-dirty page on the floor - * without writing it. - * - * We have the pages locked and the extent range locked, so there's - * no way someone can start IO on any dirty pages in this range. - * - * We'll call btrfs_dirty_pages() later on, and that will flip around - * delalloc bits and dirty the pages as required. - */ - for (i = 0; i < num_pages; i++) { - WARN_ON(!PageLocked(pages[i])); - } - - return ret; -} - static noinline int check_can_nocow(struct btrfs_inode *inode, loff_t pos, size_t *write_bytes) { @@ -1581,238 +1350,6 @@ static noinline int check_can_nocow(struct btrfs_inode *inode, loff_t pos, return ret; } -static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, - struct iov_iter *i) -{ - struct file *file = iocb->ki_filp; - loff_t pos = iocb->ki_pos; - struct inode *inode = file_inode(file); - struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); - struct btrfs_root *root = BTRFS_I(inode)->root; - struct page **pages = NULL; - struct extent_state *cached_state = NULL; - struct extent_changeset *data_reserved = NULL; - u64 release_bytes = 0; - u64 lockstart; - u64 lockend; - size_t num_written = 0; - int nrptrs; - int ret = 0; - bool only_release_metadata = false; - bool force_page_uptodate = false; - - nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE), - PAGE_SIZE / (sizeof(struct page *))); - nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied); - nrptrs = max(nrptrs, 8); - pages = kmalloc_array(nrptrs, sizeof(struct page *), GFP_KERNEL); - if (!pages) - return -ENOMEM; - - while (iov_iter_count(i) > 0) { - size_t offset = offset_in_page(pos); - size_t sector_offset; - size_t write_bytes = min(iov_iter_count(i), - nrptrs * (size_t)PAGE_SIZE - - offset); - size_t num_pages = DIV_ROUND_UP(write_bytes + offset, - PAGE_SIZE); - size_t reserve_bytes; - size_t dirty_pages; - size_t copied; - size_t dirty_sectors; - size_t num_sectors; - int extents_locked; - - WARN_ON(num_pages > nrptrs); - - /* - * Fault pages before locking them in prepare_pages - * to avoid recursive lock - */ - if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) { - ret = -EFAULT; - break; - } - - sector_offset = pos & (fs_info->sectorsize - 1); - reserve_bytes = round_up(write_bytes + sector_offset, - fs_info->sectorsize); - - extent_changeset_release(data_reserved); - ret = btrfs_check_data_free_space(inode, &data_reserved, pos, - write_bytes); - if (ret < 0) { - if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW | - BTRFS_INODE_PREALLOC)) && - check_can_nocow(BTRFS_I(inode), pos, - &write_bytes) > 0) { - /* - * For nodata cow case, no need to reserve - * data space. - */ - only_release_metadata = true; - /* - * our prealloc extent may be smaller than - * write_bytes, so scale down. - */ - num_pages = DIV_ROUND_UP(write_bytes + offset, - PAGE_SIZE); - reserve_bytes = round_up(write_bytes + - sector_offset, - fs_info->sectorsize); - } else { - break; - } - } - - WARN_ON(reserve_bytes == 0); - ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), - reserve_bytes); - if (ret) { - if (!only_release_metadata) - btrfs_free_reserved_data_space(inode, - data_reserved, pos, - write_bytes); - else - btrfs_end_write_no_snapshotting(root); - break; - } - - release_bytes = reserve_bytes; -again: - /* - * This is going to setup the pages array with the number of - * pages we want, so we don't really need to worry about the - * contents of pages from loop to loop - */ - ret = prepare_pages(inode, pages, num_pages, - pos, write_bytes, - force_page_uptodate); - if (ret) { - btrfs_delalloc_release_extents(BTRFS_I(inode), - reserve_bytes, true); - break; - } - - extents_locked = lock_and_cleanup_extent_if_need( - BTRFS_I(inode), pages, - num_pages, pos, write_bytes, &lockstart, - &lockend, &cached_state); - if (extents_locked < 0) { - if (extents_locked == -EAGAIN) - goto again; - btrfs_delalloc_release_extents(BTRFS_I(inode), - reserve_bytes, true); - ret = extents_locked; - break; - } - - copied = btrfs_copy_from_user(pos, write_bytes, pages, i); - - num_sectors = BTRFS_BYTES_TO_BLKS(fs_info, reserve_bytes); - dirty_sectors = round_up(copied + sector_offset, - fs_info->sectorsize); - dirty_sectors = BTRFS_BYTES_TO_BLKS(fs_info, dirty_sectors); - - /* - * if we have trouble faulting in the pages, fall - * back to one page at a time - */ - if (copied < write_bytes) - nrptrs = 1; - - if (copied == 0) { - force_page_uptodate = true; - dirty_sectors = 0; - dirty_pages = 0; - } else { - force_page_uptodate = false; - dirty_pages = DIV_ROUND_UP(copied + offset, - PAGE_SIZE); - } - - if (num_sectors > dirty_sectors) { - /* release everything except the sectors we dirtied */ - release_bytes -= dirty_sectors << - fs_info->sb->s_blocksize_bits; - if (only_release_metadata) { - btrfs_delalloc_release_metadata(BTRFS_I(inode), - release_bytes, true); - } else { - u64 __pos; - - __pos = round_down(pos, - fs_info->sectorsize) + - (dirty_pages << PAGE_SHIFT); - btrfs_delalloc_release_space(inode, - data_reserved, __pos, - release_bytes, true); - } - } - - release_bytes = round_up(copied + sector_offset, - fs_info->sectorsize); - - if (copied > 0) - ret = btrfs_dirty_pages(inode, pages, dirty_pages, - pos, copied, &cached_state); - if (extents_locked) - unlock_extent_cached(&BTRFS_I(inode)->io_tree, - lockstart, lockend, &cached_state); - btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes, - true); - if (ret) { - btrfs_drop_pages(pages, num_pages); - break; - } - - release_bytes = 0; - if (only_release_metadata) - btrfs_end_write_no_snapshotting(root); - - if (only_release_metadata && copied > 0) { - lockstart = round_down(pos, - fs_info->sectorsize); - lockend = round_up(pos + copied, - fs_info->sectorsize) - 1; - - set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, - lockend, EXTENT_NORESERVE, NULL, - NULL, GFP_NOFS); - only_release_metadata = false; - } - - btrfs_drop_pages(pages, num_pages); - - cond_resched(); - - balance_dirty_pages_ratelimited(inode->i_mapping); - if (dirty_pages < (fs_info->nodesize >> PAGE_SHIFT) + 1) - btrfs_btree_balance_dirty(fs_info); - - pos += copied; - num_written += copied; - } - - kfree(pages); - - if (release_bytes) { - if (only_release_metadata) { - btrfs_end_write_no_snapshotting(root); - btrfs_delalloc_release_metadata(BTRFS_I(inode), - release_bytes, true); - } else { - btrfs_delalloc_release_space(inode, data_reserved, - round_down(pos, fs_info->sectorsize), - release_bytes, true); - } - } - - extent_changeset_free(data_reserved); - return num_written ? num_written : ret; -} - static ssize_t __btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) { struct file *file = iocb->ki_filp;