Date: Fri, 18 Jan 2013 19:42:09 +0000 (UTC) From: Xin LI <delphij@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r245613 - head/sys/fs/nfsserver Message-ID: <201301181942.r0IJg9TK018072@svn.freebsd.org>
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Author: delphij Date: Fri Jan 18 19:42:08 2013 New Revision: 245613 URL: http://svnweb.freebsd.org/changeset/base/245613 Log: Make it possible to force async at server side on new NFS server, similar to the old one's nfs.nfsrv.async. Please note that by enabling this option (default is disabled), the system could potentionally have silent data corruption if the server crashes before write is committed to non-volatile storage, as the client side have no way to tell if the data is already written. Submitted by: rmacklem MFC after: 2 weeks Modified: head/sys/fs/nfsserver/nfs_nfsdserv.c Modified: head/sys/fs/nfsserver/nfs_nfsdserv.c ============================================================================== --- head/sys/fs/nfsserver/nfs_nfsdserv.c Fri Jan 18 19:11:17 2013 (r245612) +++ head/sys/fs/nfsserver/nfs_nfsdserv.c Fri Jan 18 19:42:08 2013 (r245613) @@ -55,6 +55,11 @@ extern int nfs_rootfhset; extern int nfsrv_enable_crossmntpt; #endif /* !APPLEKEXT */ +static int nfs_async = 0; +SYSCTL_DECL(_vfs_nfsd); +SYSCTL_INT(_vfs_nfsd, OID_AUTO, async, CTLFLAG_RW, &nfs_async, 0, + "Tell client that writes were synced even though they were not"); + /* * This list defines the GSS mechanisms supported. * (Don't ask me how you get these strings from the RFC stuff like @@ -912,7 +917,13 @@ nfsrvd_write(struct nfsrv_descript *nd, goto out; NFSM_BUILD(tl, u_int32_t *, 4 * NFSX_UNSIGNED); *tl++ = txdr_unsigned(retlen); - if (stable == NFSWRITE_UNSTABLE) + /* + * If nfs_async is set, then pretend the write was FILESYNC. + * Warning: Doing this violates RFC1813 and runs a risk + * of data written by a client being lost when the server + * crashes/reboots. + */ + if (stable == NFSWRITE_UNSTABLE && nfs_async == 0) *tl++ = txdr_unsigned(stable); else *tl++ = txdr_unsigned(NFSWRITE_FILESYNC);
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