From: Trond Myklebust Subject: [PATCH 2/2] NFS: Allow redirtying of a completed unstable write. Date: Mon, 16 Jun 2008 15:23:48 -0400 Message-ID: <20080616192348.20513.47394.stgit@localhost.localdomain> References: <20080616192348.20513.72423.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: Trond Myklebust To: linux-nfs@vger.kernel.org Return-path: Received: from mx2.netapp.com ([216.240.18.37]:4984 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752712AbYFPTej (ORCPT ); Mon, 16 Jun 2008 15:34:39 -0400 Received: from svlexrs02.hq.netapp.com (svlexrs02.corp.netapp.com [10.57.156.154]) by smtp2.corp.netapp.com (8.13.1/8.13.1/NTAP-1.6) with ESMTP id m5GJYWoF005004 for ; Mon, 16 Jun 2008 12:34:38 -0700 (PDT) In-Reply-To: <20080616192348.20513.72423.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: Currently, if an unstable write completes, we cannot redirty the page in order to reflect a new change in the page data until after we've sent a COMMIT request. This patch allows a page rewrite to proceed without the unnecessary COMMIT step, putting it immediately back onto the dirty page list, undoing the VM unstable write accounting, and removing the NFS_PAGE_TAG_COMMIT tag from the NFS radix tree. Signed-off-by: Trond Myklebust --- fs/nfs/write.c | 67 +++++++++++++++++++++++----------------------- include/linux/nfs_page.h | 9 ++++-- 2 files changed, 39 insertions(+), 37 deletions(-) diff --git a/fs/nfs/write.c b/fs/nfs/write.c index a675dc9..63cfe3f 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -270,12 +270,9 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio, return ret; spin_lock(&inode->i_lock); } - if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) { - /* This request is marked for commit */ + if (test_bit(PG_CLEAN, &req->wb_flags)) { spin_unlock(&inode->i_lock); - nfs_clear_page_tag_locked(req); - nfs_pageio_complete(pgio); - return 0; + BUG(); } if (nfs_set_page_writeback(page) != 0) { spin_unlock(&inode->i_lock); @@ -407,19 +404,6 @@ nfs_mark_request_dirty(struct nfs_page *req) __set_page_dirty_nobuffers(req->wb_page); } -/* - * Check if a request is dirty - */ -static inline int -nfs_dirty_request(struct nfs_page *req) -{ - struct page *page = req->wb_page; - - if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags)) - return 0; - return !PageWriteback(page); -} - #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4) /* * Add a request to the inode's commit list. @@ -432,7 +416,7 @@ nfs_mark_request_commit(struct nfs_page *req) spin_lock(&inode->i_lock); nfsi->ncommit++; - set_bit(PG_NEED_COMMIT, &(req)->wb_flags); + set_bit(PG_CLEAN, &(req)->wb_flags); radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_COMMIT); @@ -442,6 +426,19 @@ nfs_mark_request_commit(struct nfs_page *req) __mark_inode_dirty(inode, I_DIRTY_DATASYNC); } +static int +nfs_clear_request_commit(struct nfs_page *req) +{ + struct page *page = req->wb_page; + + if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) { + dec_zone_page_state(page, NR_UNSTABLE_NFS); + dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE); + return 1; + } + return 0; +} + static inline int nfs_write_need_commit(struct nfs_write_data *data) { @@ -451,7 +448,7 @@ int nfs_write_need_commit(struct nfs_write_data *data) static inline int nfs_reschedule_unstable_write(struct nfs_page *req) { - if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) { + if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) { nfs_mark_request_commit(req); return 1; } @@ -467,6 +464,12 @@ nfs_mark_request_commit(struct nfs_page *req) { } +static inline int +nfs_clear_request_commit(struct nfs_page *req) +{ + return 0; +} + static inline int nfs_write_need_commit(struct nfs_write_data *data) { @@ -524,11 +527,8 @@ static void nfs_cancel_commit_list(struct list_head *head) while(!list_empty(head)) { req = nfs_list_entry(head->next); - dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS); - dec_bdi_stat(req->wb_page->mapping->backing_dev_info, - BDI_RECLAIMABLE); nfs_list_remove_request(req); - clear_bit(PG_NEED_COMMIT, &(req)->wb_flags); + nfs_clear_request_commit(req); nfs_inode_remove_request(req); nfs_unlock_request(req); } @@ -565,7 +565,7 @@ static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pg } #endif -static int nfs_try_to_update_request(struct nfs_page *req, +static int nfs_try_to_update_request(struct inode *inode, struct nfs_page *req, unsigned int offset, unsigned int end) { @@ -579,7 +579,6 @@ static int nfs_try_to_update_request(struct nfs_page *req, * wait on the conflicting request. */ if (req->wb_page == NULL - || !nfs_dirty_request(req) || offset > rqend || end < req->wb_offset) return -EBUSY; @@ -587,6 +586,10 @@ static int nfs_try_to_update_request(struct nfs_page *req, if (!nfs_set_page_tag_locked(req)) return -EAGAIN; + if (nfs_clear_request_commit(req)) + radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree, + req->wb_index, NFS_PAGE_TAG_COMMIT); + /* Okay, the request matches. Update the region */ if (offset < req->wb_offset) { req->wb_offset = offset; @@ -623,7 +626,7 @@ static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx, spin_lock(&inode->i_lock); req = nfs_page_find_request_locked(page); if (req) { - error = nfs_try_to_update_request(req, offset, end); + error = nfs_try_to_update_request(inode, req, offset, end); spin_unlock(&inode->i_lock); if (error == 0) break; @@ -680,8 +683,7 @@ int nfs_flush_incompatible(struct file *file, struct page *page) req = nfs_page_find_request(page); if (req == NULL) return 0; - do_flush = req->wb_page != page || req->wb_context != ctx - || !nfs_dirty_request(req); + do_flush = req->wb_page != page || req->wb_context != ctx; nfs_release_request(req); if (!do_flush) return 0; @@ -1286,10 +1288,7 @@ static void nfs_commit_release(void *calldata) while (!list_empty(&data->pages)) { req = nfs_list_entry(data->pages.next); nfs_list_remove_request(req); - clear_bit(PG_NEED_COMMIT, &(req)->wb_flags); - dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS); - dec_bdi_stat(req->wb_page->mapping->backing_dev_info, - BDI_RECLAIMABLE); + nfs_clear_request_commit(req); dprintk("NFS: commit (%s/%lld %d@%lld)", req->wb_context->path.dentry->d_inode->i_sb->s_id, @@ -1465,7 +1464,7 @@ int nfs_wb_page_cancel(struct inode *inode, struct page *page) req = nfs_page_find_request(page); if (req == NULL) goto out; - if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) { + if (test_bit(PG_CLEAN, &req->wb_flags)) { nfs_release_request(req); break; } diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h index a1676e1..3c60685 100644 --- a/include/linux/nfs_page.h +++ b/include/linux/nfs_page.h @@ -27,9 +27,12 @@ /* * Valid flags for a dirty buffer */ -#define PG_BUSY 0 -#define PG_NEED_COMMIT 1 -#define PG_NEED_RESCHED 2 +enum { + PG_BUSY = 0, + PG_CLEAN, + PG_NEED_COMMIT, + PG_NEED_RESCHED, +}; struct nfs_inode; struct nfs_page {