NFS: add readdir cache array
This patch adds the readdir cache array and functions to retreive the array
stored on a cache page, clear the array by freeing allocated memory, add an
entry to the array, and search the array for a given cookie.
Signed-off-by: Bryan Schumaker <bjschuma@xxxxxxxxxx>
---
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index e257172..2e3f8d1 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -55,6 +55,7 @@ static int nfs_rename(struct inode *, struct dentry *,
struct inode *, struct dentry *);
static int nfs_fsync_dir(struct file *, int);
static loff_t nfs_llseek_dir(struct file *, loff_t, int);
+static int nfs_readdir_clear_array(struct page*, gfp_t);
const struct file_operations nfs_dir_operations = {
.llseek = nfs_llseek_dir,
@@ -80,6 +81,10 @@ const struct inode_operations nfs_dir_inode_operations = {
.setattr = nfs_setattr,
};
+const struct address_space_operations nfs_dir_addr_space_ops = {
+ .releasepage = nfs_readdir_clear_array,
+};
+
#ifdef CONFIG_NFS_V3
const struct inode_operations nfs3_dir_inode_operations = {
.create = nfs_create,
@@ -150,6 +155,21 @@ nfs_opendir(struct inode *inode, struct file *filp)
return res;
}
+struct nfs_cache_array_entry {
+ u64 cookie;
+ u64 ino;
+ struct qstr string;
+};
+
+struct nfs_cache_array {
+ unsigned int size;
+ int eof_index;
+ u64 last_cookie;
+ struct nfs_cache_array_entry array[0];
+};
+
+#define MAX_READDIR_ARRAY ((PAGE_SIZE - sizeof(struct nfs_cache_array)) / sizeof(struct nfs_cache_array_entry))
+
typedef __be32 * (*decode_dirent_t)(__be32 *, struct nfs_entry *, int);
typedef struct {
struct file *file;
@@ -164,8 +184,100 @@ typedef struct {
unsigned long timestamp;
unsigned long gencount;
int timestamp_valid;
+ unsigned int cache_entry_index;
+ unsigned int eof;
} nfs_readdir_descriptor_t;
+/*
+ * The caller is responsible for calling kunmap(page)
+ */
+static inline
+struct nfs_cache_array *nfs_readdir_get_array(struct page *page)
+{
+ if (page == NULL)
+ return ERR_PTR(-EIO);
+ return (struct nfs_cache_array *)kmap(page);
+}
+
+/*
+ * we are freeing strings created by nfs_add_to_readdir_array()
+ */
+static
+int nfs_readdir_clear_array(struct page *page, gfp_t mask)
+{
+ struct nfs_cache_array *array = nfs_readdir_get_array(page_address(page));
+ int i;
+ for (i = 0; i < array->size; i++)
+ kfree(array->array[i].string.name);
+ kunmap(page);
+ return 0;
+}
+
+/*
+ * the caller is responsible for freeing qstr.name
+ * when called by nfs_readdir_add_to_array, the strings will be freed in
+ * nfs_clear_readdir_array()
+ */
+static inline
+struct qstr nfs_readdir_make_qstr(const char *name, unsigned int len)
+{
+ struct qstr string;
+ string.len = len;
+ string.name = kmemdup(name, len, GFP_KERNEL);
+ string.hash = full_name_hash(string.name, string.len);
+ return string;
+}
+
+static
+int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
+{
+ struct nfs_cache_array *array = nfs_readdir_get_array(page);
+ if (IS_ERR(array))
+ return (size_t)array;
+ if (array->size >= MAX_READDIR_ARRAY) {
+ kunmap(page);
+ return -EIO;
+ }
+
+ array->array[array->size].cookie = entry->prev_cookie;
+ array->last_cookie = entry->cookie;
+ array->array[array->size].ino = entry->ino;
+ array->array[array->size].string = nfs_readdir_make_qstr(entry->name, entry->len);
+ if (entry->eof == 1)
+ array->eof_index = array->size;
+ array->size++;
+ kunmap(page);
+ return 0;
+}
+
+static
+int nfs_readdir_search_array(nfs_readdir_descriptor_t *desc)
+{
+ struct nfs_cache_array *array;
+ int i;
+ int status = -EBADCOOKIE;
+
+ if (desc->dir_cookie == NULL)
+ return -EBADCOOKIE;
+
+ array = nfs_readdir_get_array(desc->page);
+ if (IS_ERR(array))
+ return (size_t)array;
+
+ for (i = 0; i < array->size; i++) {
+ if (i == array->eof_index)
+ desc->eof = 1;
+ if (array->array[i].cookie == *desc->dir_cookie) {
+ desc->cache_entry_index = i;
+ status = 0;
+ goto exit;
+ }
+ }
+exit:
+ kunmap(desc->page);
+ return status;
+}
+
/* Now we cache directories properly, by stuffing the dirent
* data directly in the page cache.
*
--
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