NFS: Store the change attribute in the directory page cache

Use the change attribute and the first cookie in a directory page cache
entry to validate that the page is up to date.

Suggested-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 6f0a38d..a1767f7 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -140,6 +140,7 @@ struct nfs_cache_array_entry {
 };
 
 struct nfs_cache_array {
+       u64 change_attr;
        u64 last_cookie;
        unsigned int size;
        unsigned char page_full : 1,
@@ -176,12 +177,14 @@ static void nfs_readdir_array_init(struct nfs_cache_array *array)
        memset(array, 0, sizeof(struct nfs_cache_array));
 }
 
-static void nfs_readdir_page_init_array(struct page *page, u64 last_cookie)
+static void nfs_readdir_page_init_array(struct page *page, u64 last_cookie,
+                                       u64 change_attr)
 {
        struct nfs_cache_array *array;
 
        array = kmap_atomic(page);
        nfs_readdir_array_init(array);
+       array->change_attr = change_attr;
        array->last_cookie = last_cookie;
        array->cookies_are_ordered = 1;
        kunmap_atomic(array);
@@ -208,7 +211,7 @@ nfs_readdir_page_array_alloc(u64 last_cookie, gfp_t gfp_flags)
 {
        struct page *page = alloc_page(gfp_flags);
        if (page)
-               nfs_readdir_page_init_array(page, last_cookie);
+               nfs_readdir_page_init_array(page, last_cookie, 0);
        return page;
 }
 
@@ -305,19 +308,43 @@ out:
        return ret;
 }
 
+static bool nfs_readdir_page_validate(struct page *page, u64 last_cookie,
+                                     u64 change_attr)
+{
+       struct nfs_cache_array *array = kmap_atomic(page);
+       int ret = true;
+
+       if (array->change_attr != change_attr)
+               ret = false;
+       if (array->size > 0 && array->array[0].cookie != last_cookie)
+               ret = false;
+       kunmap_atomic(array);
+       return ret;
+}
+
+static void nfs_readdir_page_unlock_and_put(struct page *page)
+{
+       unlock_page(page);
+       put_page(page);
+}
+
 static struct page *nfs_readdir_page_get_locked(struct address_space *mapping,
                                                pgoff_t index, u64 last_cookie)
 {
        struct page *page;
+       u64 change_attr;
 
        page = grab_cache_page(mapping, index);
-       if (page && !PageUptodate(page)) {
-               nfs_readdir_page_init_array(page, last_cookie);
-               if (invalidate_inode_pages2_range(mapping, index + 1, -1) < 0)
-                       nfs_zap_mapping(mapping->host, mapping);
-               SetPageUptodate(page);
+       if (!page)
+               return NULL;
+       change_attr = inode_peek_iversion_raw(mapping->host);
+       if (PageUptodate(page)) {
+               if (nfs_readdir_page_validate(page, last_cookie, change_attr))
+                       return page;
+               nfs_readdir_clear_array(page);
        }
-
+       nfs_readdir_page_init_array(page, last_cookie, change_attr);
+       SetPageUptodate(page);
        return page;
 }
 
@@ -357,12 +384,6 @@ static void nfs_readdir_page_set_eof(struct page *page)
        kunmap_atomic(array);
 }
 
-static void nfs_readdir_page_unlock_and_put(struct page *page)
-{
-       unlock_page(page);
-       put_page(page);
-}
-
 static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
                                              pgoff_t index, u64 cookie)
 {
@@ -419,16 +440,6 @@ out_eof:
        return -EBADCOOKIE;
 }
 
-static bool
-nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
-{
-       if (nfsi->cache_validity & (NFS_INO_INVALID_CHANGE |
-                                   NFS_INO_INVALID_DATA))
-               return false;
-       smp_rmb();
-       return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
-}
-
 static bool nfs_readdir_array_cookie_in_range(struct nfs_cache_array *array,
                                              u64 cookie)
 {
@@ -457,8 +468,7 @@ static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
                        struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
 
                        new_pos = nfs_readdir_page_offset(desc->page) + i;
-                       if (desc->attr_gencount != nfsi->attr_gencount ||
-                           !nfs_readdir_inode_mapping_valid(nfsi)) {
+                       if (desc->attr_gencount != nfsi->attr_gencount) {
                                desc->duped = 0;
                                desc->attr_gencount = nfsi->attr_gencount;
                        } else if (new_pos < desc->prev_index) {
@@ -1095,11 +1105,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
         * to either find the entry with the appropriate number or
         * revalidate the cookie.
         */
-       if (ctx->pos == 0 || nfs_attribute_cache_expired(inode)) {
-               res = nfs_revalidate_mapping(inode, file->f_mapping);
-               if (res < 0)
-                       goto out;
-       }
+       nfs_revalidate_mapping(inode, file->f_mapping);
 
        res = -ENOMEM;
        desc = kzalloc(sizeof(*desc), GFP_KERNEL);