NFS: Add nfs_set_page_dirty()

We will want to allow nfs_writepage() to distinguish between pages that
have been marked as dirty by the VM, and those that have been marked as
dirty by nfs_updatepage().
In the former case, the entire page will want to be written out, and so any
requests that were pending need to be flushed out first.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 143a190..c2fe3bd 100644 (file)
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -331,7 +331,7 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
 const struct address_space_operations nfs_file_aops = {
        .readpage = nfs_readpage,
        .readpages = nfs_readpages,
-       .set_page_dirty = __set_page_dirty_nobuffers,
+       .set_page_dirty = nfs_set_page_dirty,
        .writepage = nfs_writepage,
        .writepages = nfs_writepages,
        .prepare_write = nfs_prepare_write,

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index f0720b5..266fea7 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -251,16 +251,23 @@ int nfs_writepage(struct page *page, struct writeback_control *wbc)
 {
        struct nfs_open_context *ctx;
        struct inode *inode = page->mapping->host;
+       struct nfs_page *req;
        unsigned offset;
-       int err;
+       int err = 0;
 
        nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
        nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 
-       /* Ensure we've flushed out any previous writes */
-       nfs_wb_page_priority(inode, page, wb_priority(wbc));
+       req = nfs_page_find_request(page);
+       if (req != NULL) {
+               int flushme = test_bit(PG_NEED_FLUSH, &req->wb_flags);
+               nfs_release_request(req);
+               if (!flushme)
+                       goto out;
+               /* Ensure we've flushed out the invalid write */
+               nfs_wb_page_priority(inode, page, wb_priority(wbc));
+       }
 
-       err = 0;
        offset = nfs_page_length(page);
        if (!offset)
                goto out;
@@ -655,7 +662,7 @@ int nfs_flush_incompatible(struct file *file, struct page *page)
 {
        struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
        struct nfs_page *req;
-       int             status = 0;
+       int do_flush, status;
        /*
         * Look for a request corresponding to this page. If there
         * is one, and it belongs to another file, we flush it out
@@ -664,15 +671,18 @@ int nfs_flush_incompatible(struct file *file, struct page *page)
         * Also do the same if we find a request from an existing
         * dropped page.
         */
-       req = nfs_page_find_request(page);
-       if (req != NULL) {
-               int do_flush = req->wb_page != page || req->wb_context != ctx;
-
+       do {
+               req = nfs_page_find_request(page);
+               if (req == NULL)
+                       return 0;
+               do_flush = req->wb_page != page || req->wb_context != ctx
+                       || test_bit(PG_NEED_FLUSH, &req->wb_flags);
                nfs_release_request(req);
-               if (do_flush)
-                       status = nfs_wb_page(page->mapping->host, page);
-       }
-       return (status < 0) ? status : 0;
+               if (!do_flush)
+                       return 0;
+               status = nfs_wb_page(page->mapping->host, page);
+       } while (status == 0);
+       return status;
 }
 
 /*
@@ -1437,6 +1447,19 @@ int nfs_wb_page(struct inode *inode, struct page* page)
        return nfs_wb_page_priority(inode, page, 0);
 }
 
+int nfs_set_page_dirty(struct page *page)
+{
+       struct nfs_page *req;
+
+       req = nfs_page_find_request(page);
+       if (req != NULL) {
+               /* Mark any existing write requests for flushing */
+               set_bit(PG_NEED_FLUSH, &req->wb_flags);
+               nfs_release_request(req);
+       }
+       return __set_page_dirty_nobuffers(page);
+}
+
 
 int __init nfs_init_writepagecache(void)
 {

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index f2ec9be..1b38c20 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -427,6 +427,7 @@ extern int  nfs_flush_incompatible(struct file *file, struct page *page);
 extern int  nfs_updatepage(struct file *, struct page *, unsigned int, unsigned int);
 extern int nfs_writeback_done(struct rpc_task *, struct nfs_write_data *);
 extern void nfs_writedata_release(void *);
+extern int nfs_set_page_dirty(struct page *);
 
 /*
  * Try to write back everything synchronously (but check the

diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 38aa15f..d111be6 100644 (file)
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -30,6 +30,7 @@
 #define PG_BUSY                        0
 #define PG_NEED_COMMIT         1
 #define PG_NEED_RESCHED                2
+#define PG_NEED_FLUSH          3
 
 struct nfs_inode;
 struct nfs_page {