From e468bae97d243fe0e1515abaa1f7d0edf1476ad0 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 13 Jun 2008 13:25:22 -0400 Subject: [PATCH] NFS: Allow redirtying of a completed unstable write. 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 | 65 ++++++++++++++++++++-------------------- include/linux/nfs_page.h | 9 ++++-- 2 files changed, 38 insertions(+), 36 deletions(-) diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 04f51e52e184..feca8c648766 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -242,12 +242,9 @@ 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); @@ -391,19 +388,6 @@ 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. @@ -416,7 +400,7 @@ 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); @@ -426,6 +410,19 @@ 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) { @@ -435,7 +432,7 @@ 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; } @@ -451,6 +448,12 @@ 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) { @@ -508,11 +511,8 @@ 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); } @@ -584,8 +584,7 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode, * Note: nfs_flush_incompatible() will already * have flushed out requests having wrong owners. */ - if (!nfs_dirty_request(req) - || offset > rqend + if (offset > rqend || end < req->wb_offset) goto out_flushme; @@ -601,6 +600,10 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode, spin_lock(&inode->i_lock); } + 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; @@ -682,8 +685,7 @@ 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; @@ -1288,10 +1290,7 @@ 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, @@ -1467,7 +1466,7 @@ 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 a1676e19e491..3c60685d972b 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 { -- 2.30.2