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authordillon <dillon@FreeBSD.org>2000-01-05 00:32:18 +0000
committerdillon <dillon@FreeBSD.org>2000-01-05 00:32:18 +0000
commit42026f70c270b564f3855d44f7a6bc01c797bd1c (patch)
tree5cd9e009d8c0352b18f28a3e837bcd65aabfb689 /sys/nfs
parent6beb973de0a783c029d23ae0ab672a129aea4a5f (diff)
downloadFreeBSD-src-42026f70c270b564f3855d44f7a6bc01c797bd1c.zip
FreeBSD-src-42026f70c270b564f3855d44f7a6bc01c797bd1c.tar.gz
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 <bright@wintelcom.net>
Diffstat (limited to 'sys/nfs')
-rw-r--r--sys/nfs/nfs_vnops.c24
1 files changed, 21 insertions, 3 deletions
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) {
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