From 88cc4e92dac28d9499d243f4512e63aa16e24d3b Mon Sep 17 00:00:00 2001 From: Rick Macklem Date: Wed, 22 Oct 2014 20:47:11 +0000 Subject: Clip the settings for the NFS rsize, wsize mount options to a power of 2. For non-power of 2 settings, intermittent page faults have been reported. Although the bug that causes these page faults/crashes has not been identified, it does not appear to occur when rsize, wsize is a power of 2. Reported by: tcberner@gmail.com MFC after: 2 weeks --- sys/fs/nfsclient/nfs_clvfsops.c | 36 +++++++++++++++++++++++++++--------- 1 file changed, 27 insertions(+), 9 deletions(-) diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c index 49047f69a612..5e89f0c18f75 100644 --- a/sys/fs/nfsclient/nfs_clvfsops.c +++ b/sys/fs/nfsclient/nfs_clvfsops.c @@ -552,7 +552,7 @@ static void nfs_decode_args(struct mount *mp, struct nfsmount *nmp, struct nfs_args *argp, const char *hostname, struct ucred *cred, struct thread *td) { - int s; + int i, s; int adjsock; char *p; @@ -621,18 +621,36 @@ nfs_decode_args(struct mount *mp, struct nfsmount *nmp, struct nfs_args *argp, if ((argp->flags & NFSMNT_WSIZE) && argp->wsize > 0) { nmp->nm_wsize = argp->wsize; - /* Round down to multiple of blocksize */ - nmp->nm_wsize &= ~(NFS_FABLKSIZE - 1); - if (nmp->nm_wsize <= 0) - nmp->nm_wsize = NFS_FABLKSIZE; + /* + * Clip at the power of 2 below the size. There is an + * issue (not isolated) that causes intermittent page + * faults if this is not done. + */ + i = NFS_FABLKSIZE; + for (;;) { + if (i * 2 > nmp->nm_wsize) { + nmp->nm_wsize = i; + break; + } + i *= 2; + } } if ((argp->flags & NFSMNT_RSIZE) && argp->rsize > 0) { nmp->nm_rsize = argp->rsize; - /* Round down to multiple of blocksize */ - nmp->nm_rsize &= ~(NFS_FABLKSIZE - 1); - if (nmp->nm_rsize <= 0) - nmp->nm_rsize = NFS_FABLKSIZE; + /* + * Clip at the power of 2 below the size. There is an + * issue (not isolated) that causes intermittent page + * faults if this is not done. + */ + i = NFS_FABLKSIZE; + for (;;) { + if (i * 2 > nmp->nm_rsize) { + nmp->nm_rsize = i; + break; + } + i *= 2; + } } if ((argp->flags & NFSMNT_READDIRSIZE) && argp->readdirsize > 0) { -- cgit v1.2.3