On 3 Nov 2020, at 8:35, Benjamin Coddington wrote:
On 2 Nov 2020, at 13:06, trondmy@xxxxxxxxxx wrote:
From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
---
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;
+}
+
I think we could do this calculation at compile-time instead of doing
it for
each entry, for dubious nominal gains..
and doing so might allow us to detect the case where the array is full
before doing another RPC that we'll discard.
Ben
