| Message ID | 20220331033023.718688-1-trondmy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | NFS: Replace readdir's use of xxhash() with hash_64() | expand |
Hi Trond, On Wed, 30 Mar 2022, trondmy@kernel.org wrote: > From: Trond Myklebust <trond.myklebust@hammerspace.com> > > 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> Thanks for your patch! > --- 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 I'm extremely grateful for this part! ;-) While updating shmobile_defconfig, I was wondering why I was suddenly asked about all those crypto drivers... > - 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 Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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 @@ static int nfs_readdir_page_array_append(struct page *page, * 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,