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authorTrond Myklebust <trond.myklebust@hammerspace.com>2022-03-30 20:00:07 -0400
committerTrond Myklebust <trond.myklebust@hammerspace.com>2022-04-07 16:19:47 -0400
commit830f1111d90e8770fcfad8bd5628e8ae6fecec06 (patch)
tree80bf1cd78be5bbf27593bb6e88577d340f38516b /fs
parenteb07d5a4da041fd2e30e386e5fd12d23bb31cf9e (diff)
NFS: Replace readdir's use of xxhash() with hash_64()
Both xxhash() and hash_64() appear to give similarly low collision rates with a standard linearly increasing readdir offset. They both give similarly higher collision rates when applied to ext4's offsets. So switch to using the standard hash_64(). Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfs/Kconfig4
-rw-r--r--fs/nfs/dir.c9
2 files changed, 3 insertions, 10 deletions
diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 47a53b3362b6..14a72224b657 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -4,10 +4,6 @@ config NFS_FS
depends on INET && FILE_LOCKING && MULTIUSER
select LOCKD
select SUNRPC
- select CRYPTO
- select CRYPTO_HASH
- select XXHASH
- select CRYPTO_XXHASH
select NFS_ACL_SUPPORT if NFS_V3_ACL
help
Choose Y here if you want to access files residing on other
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 0365063b85a2..c6b263b5faf1 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -39,7 +39,7 @@
#include <linux/sched.h>
#include <linux/kmemleak.h>
#include <linux/xattr.h>
-#include <linux/xxhash.h>
+#include <linux/hash.h>
#include "delegation.h"
#include "iostat.h"
@@ -350,10 +350,7 @@ out:
* of directory cookies. Content is addressed by the value of the
* cookie index of the first readdir entry in a page.
*
- * The xxhash algorithm is chosen because it is fast, and is supposed
- * to result in a decent flat distribution of hashes.
- *
- * We then select only the first 18 bits to avoid issues with excessive
+ * We select only the first 18 bits to avoid issues with excessive
* memory use for the page cache XArray. 18 bits should allow the caching
* of 262144 pages of sequences of readdir entries. Since each page holds
* 127 readdir entries for a typical 64-bit system, that works out to a
@@ -363,7 +360,7 @@ static pgoff_t nfs_readdir_page_cookie_hash(u64 cookie)
{
if (cookie == 0)
return 0;
- return xxhash(&cookie, sizeof(cookie), 0) & NFS_READDIR_COOKIE_MASK;
+ return hash_64(cookie, 18);
}
static bool nfs_readdir_page_validate(struct page *page, u64 last_cookie,