Date: Wed, 22 Oct 2014 20:47:11 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r273481 - head/sys/fs/nfsclient Message-ID: <201410222047.s9MKlBut062991@svn.freebsd.org>
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Author: rmacklem Date: Wed Oct 22 20:47:11 2014 New Revision: 273481 URL: https://svnweb.freebsd.org/changeset/base/273481 Log: 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 Modified: head/sys/fs/nfsclient/nfs_clvfsops.c Modified: head/sys/fs/nfsclient/nfs_clvfsops.c ============================================================================== --- head/sys/fs/nfsclient/nfs_clvfsops.c Wed Oct 22 18:55:44 2014 (r273480) +++ head/sys/fs/nfsclient/nfs_clvfsops.c Wed Oct 22 20:47:11 2014 (r273481) @@ -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 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) {
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