From 830f1111d90e8770fcfad8bd5628e8ae6fecec06 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 30 Mar 2022 20:00:07 -0400 Subject: 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 --- fs/nfs/Kconfig | 4 ---- fs/nfs/dir.c | 9 +++------ 2 files changed, 3 insertions(+), 10 deletions(-) (limited to 'fs/nfs') 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 #include #include -#include +#include #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, -- cgit v1.2.3