[PATCH v4 04/21] NFS: Clean up readdir struct nfs_cache_array

trondmy
2020-11-07T14:13:40Z

Since the 'eof_index' is only ever used as a flag, make it so.
Also add a flag to detect if the page has been completely filled.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
fs/nfs/dir.c | 66 ++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 49 insertions(+), 17 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 67d8595cd6e5..604ebe015387 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -138,9 +138,10 @@ struct nfs_cache_array_entry {
};

struct nfs_cache_array {
- int size;
- int eof_index;
u64 last_cookie;
+ unsigned int size;
+ unsigned char page_full : 1,
+ page_is_eof : 1;
struct nfs_cache_array_entry array[];
};

@@ -172,7 +173,6 @@ void nfs_readdir_init_array(struct page *page)

array = kmap_atomic(page);
memset(array, 0, sizeof(struct nfs_cache_array));
- array->eof_index = -1;
kunmap_atomic(array);
}

@@ -192,6 +192,17 @@ void nfs_readdir_clear_array(struct page *page)
kunmap_atomic(array);
}

+static void nfs_readdir_array_set_eof(struct nfs_cache_array *array)
+{
+ array->page_is_eof = 1;
+ array->page_full = 1;
+}
+
+static bool nfs_readdir_array_is_full(struct nfs_cache_array *array)
+{
+ return array->page_full;
+}
+
/*
* the caller is responsible for freeing qstr.name
* when called by nfs_readdir_add_to_array, the strings will be freed in
@@ -213,6 +224,23 @@ int nfs_readdir_make_qstr(struct qstr *string, const char *name, unsigned int le
return 0;
}

+/*
+ * Check that the next array entry lies entirely within the page bounds
+ */
+static int nfs_readdir_array_can_expand(struct nfs_cache_array *array)
+{
+ struct nfs_cache_array_entry *cache_entry;
+
+ if (array->page_full)
+ return -ENOSPC;
+ cache_entry = &array->array[array->size + 1];
+ if ((char *)cache_entry - (char *)array > PAGE_SIZE) {
+ array->page_full = 1;
+ return -ENOSPC;
+ }
+ return 0;
+}
+
static
int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
{
@@ -220,13 +248,11 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
struct nfs_cache_array_entry *cache_entry;
int ret;

- cache_entry = &array->array[array->size];
-
- /* Check that this entry lies within the page bounds */
- ret = -ENOSPC;
- if ((char *)&cache_entry[1] - (char *)page_address(page) > PAGE_SIZE)
+ ret = nfs_readdir_array_can_expand(array);
+ if (ret)
goto out;

+ cache_entry = &array->array[array->size];
cache_entry->cookie = entry->prev_cookie;
cache_entry->ino = entry->ino;
cache_entry->d_type = entry->d_type;
@@ -236,12 +262,21 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
array->last_cookie = entry->cookie;
array->size++;
if (entry->eof != 0)
- array->eof_index = array->size;
+ nfs_readdir_array_set_eof(array);
out:
kunmap(page);
return ret;
}

+static void nfs_readdir_page_set_eof(struct page *page)
+{
+ struct nfs_cache_array *array;
+
+ array = kmap_atomic(page);
+ nfs_readdir_array_set_eof(array);
+ kunmap_atomic(array);
+}
+
static inline
int is_32bit_api(void)
{
@@ -270,7 +305,7 @@ int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descri
if (diff < 0)
goto out_eof;
if (diff >= array->size) {
- if (array->eof_index >= 0)
+ if (array->page_is_eof)
goto out_eof;
return -EAGAIN;
}
@@ -334,7 +369,7 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
return 0;
}
}
- if (array->eof_index >= 0) {
+ if (array->page_is_eof) {
status = -EBADCOOKIE;
if (desc->dir_cookie == array->last_cookie)
desc->eof = true;
@@ -566,7 +601,6 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
struct xdr_stream stream;
struct xdr_buf buf;
struct page *scratch;
- struct nfs_cache_array *array;
unsigned int count = 0;
int status;

@@ -604,10 +638,8 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en

out_nopages:
if (count == 0 || (status == -EBADCOOKIE && entry->eof != 0)) {
- array = kmap(page);
- array->eof_index = array->size;
+ nfs_readdir_page_set_eof(page);
status = 0;
- kunmap(page);
}

put_page(scratch);
@@ -689,7 +721,7 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
status = 0;
break;
}
- } while (array->eof_index < 0);
+ } while (!nfs_readdir_array_is_full(array));

nfs_readdir_free_pages(pages, array_size);
out_release_array:
@@ -825,7 +857,7 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
if (desc->duped != 0)
desc->duped = 1;
}
- if (array->eof_index >= 0)
+ if (array->page_is_eof)
desc->eof = true;

kunmap(desc->page);
--
2.28.0