Commit d09e673f authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 0b2662b7

fs/nfs/dir.c

+37 −31
Original line number Diff line number Diff line
@@ -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 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page) 
	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 @@ static int nfs_readdir_search_for_pos(struct nfs_cache_array *array, 
	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);