From patchwork Fri Nov 17 21:15:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13459483 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OYlkiD5e" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABA063588 for ; Fri, 17 Nov 2023 13:17:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700255874; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8vjTTCvvYvaQCYuD/oiutq3ZhL8gEcV49d8YEYcq98w=; b=OYlkiD5eY4xGgxMiD0pidq9i27cwBmHc/6uj12O7tFK/KeEMbNzjmhtGWMB8PGYNy0ghVF YeI2MreTSJqRvtG6U6BWJwanhcRg9/YSDkSKxNqKa43nrtYZQKNDeC4j45p6rxDsBKtjPp MdxARY5IR5dm1A72PfQeDqGDK9+mWe8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-690-ZuED85X7OhS3rKs8y1YvUA-1; Fri, 17 Nov 2023 16:17:51 -0500 X-MC-Unique: ZuED85X7OhS3rKs8y1YvUA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0D69D101A594; Fri, 17 Nov 2023 21:17:50 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.42.28.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5302D5036; Fri, 17 Nov 2023 21:17:47 +0000 (UTC) From: David Howells To: Jeff Layton , Steve French Cc: David Howells , Matthew Wilcox , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Dominique Martinet , Ilya Dryomov , Christian Brauner , linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 30/51] netfs: Provide a writepages implementation Date: Fri, 17 Nov 2023 21:15:22 +0000 Message-ID: <20231117211544.1740466-31-dhowells@redhat.com> In-Reply-To: <20231117211544.1740466-1-dhowells@redhat.com> References: <20231117211544.1740466-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Provide an implementation of writepages for network filesystems to delegate to. Signed-off-by: David Howells cc: Jeff Layton cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- fs/netfs/buffered_write.c | 625 ++++++++++++++++++++++++++++++++++++++ include/linux/netfs.h | 2 + 2 files changed, 627 insertions(+) diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c index 3c1f26f32351..097086d75d1c 100644 --- a/fs/netfs/buffered_write.c +++ b/fs/netfs/buffered_write.c @@ -32,6 +32,18 @@ static void netfs_set_group(struct folio *folio, struct netfs_group *netfs_group folio_attach_private(folio, netfs_get_group(netfs_group)); } +#if IS_ENABLED(CONFIG_FSCACHE) +static void netfs_folio_start_fscache(bool caching, struct folio *folio) +{ + if (caching) + folio_start_fscache(folio); +} +#else +static void netfs_folio_start_fscache(bool caching, struct folio *folio) +{ +} +#endif + /* * Decide how we should modify a folio. We might be attempting to do * write-streaming, in which case we don't want to a local RMW cycle if we can @@ -472,3 +484,616 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr return ret; } EXPORT_SYMBOL(netfs_page_mkwrite); + +/* + * Kill all the pages in the given range + */ +static void netfs_kill_pages(struct address_space *mapping, + loff_t start, loff_t len) +{ + struct folio *folio; + pgoff_t index = start / PAGE_SIZE; + pgoff_t last = (start + len - 1) / PAGE_SIZE, next; + + _enter("%llx-%llx", start, start + len - 1); + + do { + _debug("kill %lx (to %lx)", index, last); + + folio = filemap_get_folio(mapping, index); + if (IS_ERR(folio)) { + next = index + 1; + continue; + } + + next = folio_next_index(folio); + + folio_clear_uptodate(folio); + folio_end_writeback(folio); + folio_lock(folio); + trace_netfs_folio(folio, netfs_folio_trace_kill); + generic_error_remove_page(mapping, &folio->page); + folio_unlock(folio); + folio_put(folio); + + } while (index = next, index <= last); + + _leave(""); +} + +/* + * Redirty all the pages in a given range. + */ +static void netfs_redirty_pages(struct address_space *mapping, + loff_t start, loff_t len) +{ + struct folio *folio; + pgoff_t index = start / PAGE_SIZE; + pgoff_t last = (start + len - 1) / PAGE_SIZE, next; + + _enter("%llx-%llx", start, start + len - 1); + + do { + _debug("redirty %llx @%llx", len, start); + + folio = filemap_get_folio(mapping, index); + if (IS_ERR(folio)) { + next = index + 1; + continue; + } + + next = folio_next_index(folio); + trace_netfs_folio(folio, netfs_folio_trace_redirty); + filemap_dirty_folio(mapping, folio); + folio_end_writeback(folio); + folio_put(folio); + } while (index = next, index <= last); + + balance_dirty_pages_ratelimited(mapping); + + _leave(""); +} + +/* + * Completion of write to server + */ +static void netfs_pages_written_back(struct netfs_io_request *wreq) +{ + struct address_space *mapping = wreq->mapping; + struct netfs_folio *finfo; + struct netfs_group *group = NULL; + struct folio *folio; + pgoff_t last; + int gcount = 0; + + XA_STATE(xas, &mapping->i_pages, wreq->start / PAGE_SIZE); + + _enter("%llx-%llx", wreq->start, wreq->start + wreq->len); + + rcu_read_lock(); + + last = (wreq->start + wreq->len - 1) / PAGE_SIZE; + xas_for_each(&xas, folio, last) { + WARN(!folio_test_writeback(folio), + "bad %zx @%llx page %lx %lx\n", + wreq->len, wreq->start, folio_index(folio), last); + + if ((finfo = netfs_folio_info(folio))) { + /* Streaming writes cannot be redirtied whilst under + * writeback, so discard the streaming record. + */ + folio_detach_private(folio); + group = finfo->netfs_group; + gcount++; + trace_netfs_folio(folio, netfs_folio_trace_clear_s); + } else if ((group = netfs_folio_group(folio))) { + /* Need to detach the group pointer if the page didn't + * get redirtied. If it has been redirtied, then it + * must be within the same group. + */ + if (folio_test_dirty(folio)) { + trace_netfs_folio(folio, netfs_folio_trace_redirtied); + goto end_wb; + } + if (folio_trylock(folio)) { + if (!folio_test_dirty(folio)) { + folio_detach_private(folio); + gcount++; + trace_netfs_folio(folio, netfs_folio_trace_clear_g); + } else { + trace_netfs_folio(folio, netfs_folio_trace_redirtied); + } + folio_unlock(folio); + goto end_wb; + } + + xas_pause(&xas); + rcu_read_unlock(); + folio_lock(folio); + if (!folio_test_dirty(folio)) { + folio_detach_private(folio); + gcount++; + trace_netfs_folio(folio, netfs_folio_trace_clear_g); + } else { + trace_netfs_folio(folio, netfs_folio_trace_redirtied); + } + folio_unlock(folio); + rcu_read_lock(); + } else { + trace_netfs_folio(folio, netfs_folio_trace_clear); + } + end_wb: + folio_end_writeback(folio); + } + + rcu_read_unlock(); + netfs_put_group_many(group, gcount); + _leave(""); +} + +/* + * Deal with the disposition of the folios that are under writeback to close + * out the operation. + */ +static void netfs_cleanup_buffered_write(struct netfs_io_request *wreq) +{ + struct address_space *mapping = wreq->mapping; + + _enter(""); + + switch (wreq->error) { + case 0: + netfs_pages_written_back(wreq); + break; + + default: + pr_notice("R=%08x Unexpected error %d\n", wreq->debug_id, wreq->error); + fallthrough; + case -EACCES: + case -EPERM: + case -ENOKEY: + case -EKEYEXPIRED: + case -EKEYREJECTED: + case -EKEYREVOKED: + case -ENETRESET: + case -EDQUOT: + case -ENOSPC: + netfs_redirty_pages(mapping, wreq->start, wreq->len); + break; + + case -EROFS: + case -EIO: + case -EREMOTEIO: + case -EFBIG: + case -ENOENT: + case -ENOMEDIUM: + case -ENXIO: + netfs_kill_pages(mapping, wreq->start, wreq->len); + break; + } + + if (wreq->error) + mapping_set_error(mapping, wreq->error); + if (wreq->netfs_ops->done) + wreq->netfs_ops->done(wreq); +} + +/* + * Extend the region to be written back to include subsequent contiguously + * dirty pages if possible, but don't sleep while doing so. + * + * If this page holds new content, then we can include filler zeros in the + * writeback. + */ +static void netfs_extend_writeback(struct address_space *mapping, + struct netfs_group *group, + struct xa_state *xas, + long *_count, + loff_t start, + loff_t max_len, + bool caching, + size_t *_len) +{ + struct netfs_folio *finfo; + struct folio_batch fbatch; + struct folio *folio; + unsigned int i; + pgoff_t index = (start + *_len) / PAGE_SIZE; + size_t len; + void *priv; + bool stop = true; + + folio_batch_init(&fbatch); + + do { + /* Firstly, we gather up a batch of contiguous dirty pages + * under the RCU read lock - but we can't clear the dirty flags + * there if any of those pages are mapped. + */ + rcu_read_lock(); + + xas_for_each(xas, folio, ULONG_MAX) { + stop = true; + if (xas_retry(xas, folio)) + continue; + if (xa_is_value(folio)) + break; + if (folio_index(folio) != index) + break; + + priv = rcu_dereference(*(__force void __rcu **)&folio->private); + if ((const struct netfs_group *)priv != group) { + finfo = (void *)((unsigned long)priv & ~NETFS_FOLIO_INFO); + if (finfo->netfs_group != group) + break; + if (finfo->dirty_offset > 0) + break; + } + + if (!folio_try_get_rcu(folio)) { + xas_reset(xas); + continue; + } + + /* Has the folio moved or been split? */ + if (unlikely(folio != xas_reload(xas))) { + folio_put(folio); + break; + } + + if (!folio_trylock(folio)) { + folio_put(folio); + break; + } + if (!folio_test_dirty(folio) || + folio_test_writeback(folio) || + folio_test_fscache(folio)) { + folio_unlock(folio); + folio_put(folio); + break; + } + + stop = false; + len = folio_size(folio); + priv = folio->private; + if ((const struct netfs_group *)priv != group) { + stop = true; + finfo = (void *)((unsigned long)priv & ~NETFS_FOLIO_INFO); + if (finfo->netfs_group != group || + finfo->dirty_offset > 0) { + folio_unlock(folio); + folio_put(folio); + break; + } + len = finfo->dirty_len; + } + + index += folio_nr_pages(folio); + *_count -= folio_nr_pages(folio); + *_len += len; + if (*_len >= max_len || *_count <= 0) + stop = true; + + if (!folio_batch_add(&fbatch, folio)) + break; + if (stop) + break; + } + + xas_pause(xas); + rcu_read_unlock(); + + /* Now, if we obtained any folios, we can shift them to being + * writable and mark them for caching. + */ + if (!folio_batch_count(&fbatch)) + break; + + for (i = 0; i < folio_batch_count(&fbatch); i++) { + folio = fbatch.folios[i]; + trace_netfs_folio(folio, netfs_folio_trace_store_plus); + + if (!folio_clear_dirty_for_io(folio)) + BUG(); + folio_start_writeback(folio); + netfs_folio_start_fscache(caching, folio); + folio_unlock(folio); + } + + folio_batch_release(&fbatch); + cond_resched(); + } while (!stop); +} + +/* + * Synchronously write back the locked page and any subsequent non-locked dirty + * pages. + */ +static ssize_t netfs_write_back_from_locked_folio(struct address_space *mapping, + struct writeback_control *wbc, + struct netfs_group *group, + struct xa_state *xas, + struct folio *folio, + unsigned long long start, + unsigned long long end) +{ + struct netfs_io_request *wreq; + struct netfs_folio *finfo; + struct netfs_inode *ctx = netfs_inode(mapping->host); + unsigned long long i_size = i_size_read(&ctx->inode); + size_t len, max_len; + bool caching = netfs_is_cache_enabled(ctx); + long count = wbc->nr_to_write; + int ret; + + _enter(",%lx,%llx-%llx,%u", folio_index(folio), start, end, caching); + + wreq = netfs_alloc_request(mapping, NULL, start, folio_size(folio), + NETFS_WRITEBACK); + if (IS_ERR(wreq)) + return PTR_ERR(wreq); + + if (!folio_clear_dirty_for_io(folio)) + BUG(); + folio_start_writeback(folio); + netfs_folio_start_fscache(caching, folio); + + count -= folio_nr_pages(folio); + + /* Find all consecutive lockable dirty pages that have contiguous + * written regions, stopping when we find a page that is not + * immediately lockable, is not dirty or is missing, or we reach the + * end of the range. + */ + trace_netfs_folio(folio, netfs_folio_trace_store); + + len = folio_size(folio); + finfo = netfs_folio_info(folio); + if (finfo) { + start += finfo->dirty_offset; + if (finfo->dirty_offset + finfo->dirty_len != len) { + len = finfo->dirty_len; + goto cant_expand; + } + len = finfo->dirty_len; + } + + if (start < i_size) { + /* Trim the write to the EOF; the extra data is ignored. Also + * put an upper limit on the size of a single storedata op. + */ + max_len = 65536 * 4096; + max_len = min_t(unsigned long long, max_len, end - start + 1); + max_len = min_t(unsigned long long, max_len, i_size - start); + + if (len < max_len) + netfs_extend_writeback(mapping, group, xas, &count, + start, max_len, caching, &len); + } + +cant_expand: + len = min_t(unsigned long long, len, i_size - start); + + /* We now have a contiguous set of dirty pages, each with writeback + * set; the first page is still locked at this point, but all the rest + * have been unlocked. + */ + folio_unlock(folio); + wreq->start = start; + wreq->len = len; + + if (start < i_size) { + _debug("write back %zx @%llx [%llx]", len, start, i_size); + + /* Speculatively write to the cache. We have to fix this up + * later if the store fails. + */ + wreq->cleanup = netfs_cleanup_buffered_write; + + iov_iter_xarray(&wreq->iter, ITER_SOURCE, &mapping->i_pages, start, len); + __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); + ret = netfs_begin_write(wreq, true, netfs_write_trace_writeback); + if (ret == 0 || ret == -EIOCBQUEUED) + wbc->nr_to_write -= len / PAGE_SIZE; + } else { + _debug("write discard %zx @%llx [%llx]", len, start, i_size); + + /* The dirty region was entirely beyond the EOF. */ + fscache_clear_page_bits(mapping, start, len, caching); + netfs_pages_written_back(wreq); + ret = 0; + } + + netfs_put_request(wreq, false, netfs_rreq_trace_put_return); + _leave(" = 0"); + return 0; +} + +/* + * Write a region of pages back to the server + */ +static ssize_t netfs_writepages_begin(struct address_space *mapping, + struct writeback_control *wbc, + struct netfs_group *group, + struct xa_state *xas, + unsigned long long *_start, + unsigned long long end) +{ + const struct netfs_folio *finfo; + struct folio *folio; + unsigned long long start = *_start; + ssize_t ret; + void *priv; + int skips = 0; + + _enter("%llx,%llx,", start, end); + +search_again: + /* Find the first dirty page in the group. */ + rcu_read_lock(); + + for (;;) { + folio = xas_find_marked(xas, end / PAGE_SIZE, PAGECACHE_TAG_DIRTY); + if (xas_retry(xas, folio) || xa_is_value(folio)) + continue; + if (!folio) + break; + + /* Skip any dirty folio that's not in the group of interest. */ + priv = rcu_dereference(*(__force void __rcu **)&folio->private); + if ((const struct netfs_group *)priv != group) { + finfo = (void *)((unsigned long)priv & ~NETFS_FOLIO_INFO); + if (finfo->netfs_group != group) + continue; + } + + if (!folio_try_get_rcu(folio)) { + xas_reset(xas); + continue; + } + + if (unlikely(folio != xas_reload(xas))) { + folio_put(folio); + xas_reset(xas); + continue; + } + + xas_pause(xas); + break; + } + rcu_read_unlock(); + if (!folio) + return 0; + + start = folio_pos(folio); /* May regress with THPs */ + + _debug("wback %lx", folio_index(folio)); + + /* At this point we hold neither the i_pages lock nor the page lock: + * the page may be truncated or invalidated (changing page->mapping to + * NULL), or even swizzled back from swapper_space to tmpfs file + * mapping + */ +lock_again: + if (wbc->sync_mode != WB_SYNC_NONE) { + ret = folio_lock_killable(folio); + if (ret < 0) + return ret; + } else { + if (!folio_trylock(folio)) + goto search_again; + } + + if (folio->mapping != mapping || + !folio_test_dirty(folio)) { + start += folio_size(folio); + folio_unlock(folio); + goto search_again; + } + + if (folio_test_writeback(folio) || + folio_test_fscache(folio)) { + folio_unlock(folio); + if (wbc->sync_mode != WB_SYNC_NONE) { + folio_wait_writeback(folio); +#ifdef CONFIG_NETFS_FSCACHE + folio_wait_fscache(folio); +#endif + goto lock_again; + } + + start += folio_size(folio); + if (wbc->sync_mode == WB_SYNC_NONE) { + if (skips >= 5 || need_resched()) { + ret = 0; + goto out; + } + skips++; + } + goto search_again; + } + + ret = netfs_write_back_from_locked_folio(mapping, wbc, group, xas, + folio, start, end); +out: + if (ret > 0) + *_start = start + ret; + _leave(" = %zd [%llx]", ret, *_start); + return ret; +} + +/* + * Write a region of pages back to the server + */ +static int netfs_writepages_region(struct address_space *mapping, + struct writeback_control *wbc, + struct netfs_group *group, + unsigned long long *_start, + unsigned long long end) +{ + ssize_t ret; + + XA_STATE(xas, &mapping->i_pages, *_start / PAGE_SIZE); + + do { + ret = netfs_writepages_begin(mapping, wbc, group, &xas, + _start, end); + if (ret > 0 && wbc->nr_to_write > 0) + cond_resched(); + } while (ret > 0 && wbc->nr_to_write > 0); + + return ret > 0 ? 0 : ret; +} + +/* + * write some of the pending data back to the server + */ +int netfs_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct netfs_group *group = NULL; + loff_t start, end; + int ret; + + _enter(""); + + /* We have to be careful as we can end up racing with setattr() + * truncating the pagecache since the caller doesn't take a lock here + * to prevent it. + */ + + if (wbc->range_cyclic && mapping->writeback_index) { + start = mapping->writeback_index * PAGE_SIZE; + ret = netfs_writepages_region(mapping, wbc, group, + &start, LLONG_MAX); + if (ret < 0) + goto out; + + if (wbc->nr_to_write <= 0) { + mapping->writeback_index = start / PAGE_SIZE; + goto out; + } + + start = 0; + end = mapping->writeback_index * PAGE_SIZE; + mapping->writeback_index = 0; + ret = netfs_writepages_region(mapping, wbc, group, &start, end); + if (ret == 0) + mapping->writeback_index = start / PAGE_SIZE; + } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) { + start = 0; + ret = netfs_writepages_region(mapping, wbc, group, + &start, LLONG_MAX); + if (wbc->nr_to_write > 0 && ret == 0) + mapping->writeback_index = start / PAGE_SIZE; + } else { + start = wbc->range_start; + ret = netfs_writepages_region(mapping, wbc, group, + &start, wbc->range_end); + } + +out: + _leave(" = %d", ret); + return ret; +} +EXPORT_SYMBOL(netfs_writepages); diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 2ab989407dcb..02a8ddddc8cd 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -402,6 +402,8 @@ int netfs_read_folio(struct file *, struct folio *); int netfs_write_begin(struct netfs_inode *, struct file *, struct address_space *, loff_t pos, unsigned int len, struct folio **, void **fsdata); +int netfs_writepages(struct address_space *mapping, + struct writeback_control *wbc); void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length); bool netfs_release_folio(struct folio *folio, gfp_t gfp);