pnfsblock: move find lock page logic out of bl_write_pagelist

Also avoid unnecessary lock_page if page is handled by others.

Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 54 insertions, 24 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index a263810803c1..234273621854 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -490,6 +490,55 @@ cleanup:
         return ret;
 }
 
+/* Find or create a zeroing page marked being writeback.
+ * Return ERR_PTR on error, NULL to indicate skip this page and page itself
+ * to indicate write out.
+ */
+static struct page *
+bl_find_get_zeroing_page(struct inode *inode, pgoff_t index,
+                        struct pnfs_block_extent *cow_read)
+{
+        struct page *page;
+        int locked = 0;
+        page = find_get_page(inode->i_mapping, index);
+        if (page)
+                goto check_page;
+
+        page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
+        if (unlikely(!page)) {
+                dprintk("%s oom\n", __func__);
+                return ERR_PTR(-ENOMEM);
+        }
+        locked = 1;
+
+check_page:
+        /* PageDirty: Other will write this out
+         * PageWriteback: Other is writing this out
+         * PageUptodate: It was read before
+         */
+        if (PageDirty(page) || PageWriteback(page)) {
+                print_page(page);
+                if (locked)
+                        unlock_page(page);
+                page_cache_release(page);
+                return NULL;
+        }
+
+        if (!locked) {
+                lock_page(page);
+                locked = 1;
+                goto check_page;
+        }
+        if (!PageUptodate(page)) {
+                /* New page, readin or zero it */
+                init_page_for_write(page, cow_read);
+        }
+        set_page_writeback(page);
+        unlock_page(page);
+
+        return page;
+}
+
 static enum pnfs_try_status
 bl_write_pagelist(struct nfs_write_data *wdata, int sync)
 {
@@ -549,32 +598,13 @@ fill_invalid_ext:
                         dprintk("%s zero %dth page: index %lu isect %llu\n",
                                 __func__, npg_zero, index,
                                 (unsigned long long)isect);
-                        page =
-                            find_or_create_page(wdata->inode->i_mapping, index,
-                                                GFP_NOFS);
-                        if (!page) {
-                                dprintk("%s oom\n", __func__);
-                                wdata->pnfs_error = -ENOMEM;
+                        page = bl_find_get_zeroing_page(wdata->inode, index,
+                                                        cow_read);
+                        if (unlikely(IS_ERR(page))) {
+                                wdata->pnfs_error = PTR_ERR(page);
                                 goto out;
-                        }
-
-                        /* PageDirty: Other will write this out
-                         * PageWriteback: Other is writing this out
-                         * PageUptodate: It was read before
-                         * sector_initialized: already written out
-                         */
-                        if (PageDirty(page) || PageWriteback(page)) {
-                                print_page(page);
-                                unlock_page(page);
-                                page_cache_release(page);
+                        } else if (page == NULL)
                                 goto next_page;
-                        }
-                        if (!PageUptodate(page)) {
-                                /* New page, readin or zero it */
-                                init_page_for_write(page, cow_read);
-                        }
-                        set_page_writeback(page);
-                        unlock_page(page);
 
                         ret = bl_mark_sectors_init(be->be_inval, isect,
                                                        PAGE_CACHE_SECTORS);