From 42026f70c270b564f3855d44f7a6bc01c797bd1c Mon Sep 17 00:00:00 2001 From: dillon Date: Wed, 5 Jan 2000 00:32:18 +0000 Subject: Fix at least one source of the continued 'NFS append race'. close() was calling nfs_flush() and then clearing the NMODIFIED bit. This is not legal since there might still be dirty buffers after the nfs_flush (for example, pending commits). The clearing of this bit in turn prevented a necessary vinvalbuf() from occuring leaving left over dirty buffers even after truncating the file in a new operation. The fix is to simply not clear NMODIFIED. Also added a sysctl vfs.nfs.nfsv3_commit_on_close which, if set to 1, will cause close() to do a stage 1 write AND a stage 2 commit synchronously. By default only the stage 1 write is done synchronously. Reviewed by: Alfred Perlstein --- sys/nfs/nfs_vnops.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) (limited to 'sys/nfs') diff --git a/sys/nfs/nfs_vnops.c b/sys/nfs/nfs_vnops.c index 4097d96..0a6de2f 100644 --- a/sys/nfs/nfs_vnops.c +++ b/sys/nfs/nfs_vnops.c @@ -251,6 +251,9 @@ static int nfsaccess_cache_timeout = NFS_MAXATTRTIMO; SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_timeout, CTLFLAG_RW, &nfsaccess_cache_timeout, 0, "NFS ACCESS cache timeout"); +static int nfsv3_commit_on_close = 0; +SYSCTL_INT(_vfs_nfs, OID_AUTO, nfsv3_commit_on_close, CTLFLAG_RW, + &nfsv3_commit_on_close, 0, "write+commit on close, else only write"); #if 0 SYSCTL_INT(_vfs_nfs, OID_AUTO, access_cache_hits, CTLFLAG_RD, &nfsstats.accesscache_hits, 0, "NFS ACCESS cache hit count"); @@ -561,10 +564,25 @@ nfs_close(ap) if ((VFSTONFS(vp->v_mount)->nm_flag & NFSMNT_NQNFS) == 0 && (np->n_flag & NMODIFIED)) { if (NFS_ISV3(vp)) { - error = nfs_flush(vp, ap->a_cred, MNT_WAIT, ap->a_p, 0); - np->n_flag &= ~NMODIFIED; - } else + /* + * Under NFSv3 we have dirty buffers to dispose of. We + * must flush them to the NFS server. We have the option + * of waiting all the way through the commit rpc or just + * waiting for the initial write. The default is to only + * wait through the initial write so the data is in the + * server's cache, which is roughly similar to the state + * a standard disk subsystem leaves the file in on close(). + * + * We cannot clear the NMODIFIED bit in np->n_flag due to + * potential races with other processes, and certainly + * cannot clear it if we don't commit. + */ + int cm = nfsv3_commit_on_close ? 1 : 0; + error = nfs_flush(vp, ap->a_cred, MNT_WAIT, ap->a_p, cm); + /* np->n_flag &= ~NMODIFIED; */ + } else { error = nfs_vinvalbuf(vp, V_SAVE, ap->a_cred, ap->a_p, 1); + } np->n_attrstamp = 0; } if (np->n_flag & NWRITEERR) { -- cgit v1.1