NFSD: Write verifier might go backwards

chucklever · chucklever · commit cdc556600c01 · 2022-01-08T14:42:02.000-05:00
When vfs_iter_write() starts to fail because a file system is full,
a bunch of writes can fail at once with ENOSPC. These writes
repeatedly invoke nfsd_reset_boot_verifier() in quick succession.

Ensure that the time it grabs doesn't go backwards due to an ntp
adjustment going on at the same time.

Signed-off-by: Chuck Lever &lt;chuck.lever@oracle.com&gt;
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
@@ -363,7 +363,7 @@ void nfsd_copy_boot_verifier(__be32 verf[2], struct nfsd_net *nn)
 
 static void nfsd_reset_boot_verifier_locked(struct nfsd_net *nn)
 {
-	ktime_get_real_ts64(&nn->nfssvc_boot);
+	ktime_get_raw_ts64(&nn->nfssvc_boot);
 }
 
 void nfsd_reset_boot_verifier(struct nfsd_net *nn)

Original file line number	Diff line number	Diff line change
`@@ -363,7 +363,7 @@ void nfsd_copy_boot_verifier(__be32 verf[2], struct nfsd_net *nn)`
`363`	`363`
`364`	`364`	`static void nfsd_reset_boot_verifier_locked(struct nfsd_net *nn)`
`365`	`365`	`{`
`366`		`- ktime_get_real_ts64(&nn->nfssvc_boot);`
	`366`	`+ ktime_get_raw_ts64(&nn->nfssvc_boot);`
`367`	`367`	`}`
`368`	`368`
`369`	`369`	`void nfsd_reset_boot_verifier(struct nfsd_net *nn)`