afs: Fix missing net error handling

kAFS can be given certain network errors (EADDRNOTAVAIL, EHOSTDOWN and
ERFKILL) that it doesn't handle in its server/address rotation algorithms.
They cause the probing and rotation to abort immediately rather than
rotating.

Fix this by:

 (1) Abstracting out the error prioritisation from the VL and FS rotation
     algorithms into a common function and expand usage into the server
     probing code.

     When multiple errors are available, this code selects the one we'd
     prefer to return.

 (2) Add handling for EADDRNOTAVAIL, EHOSTDOWN and ERFKILL.

Fixes: 0fafdc9f888b ("afs: Fix file locking")
Fixes: 0338747d8454 ("afs: Probe multiple fileservers simultaneously")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 52 insertions, 0 deletions

diff --git a/fs/afs/misc.c b/fs/afs/misc.c
index 700a5fa7f4ec..bbb1fd51b019 100644
--- a/fs/afs/misc.c
+++ b/fs/afs/misc.c
@@ -118,3 +118,55 @@ int afs_abort_to_error(u32 abort_code)
 	default:		return -EREMOTEIO;
 	}
 }
+
+/*
+ * Select the error to report from a set of errors.
+ */
+void afs_prioritise_error(struct afs_error *e, int error, u32 abort_code)
+{
+	switch (error) {
+	case 0:
+		return;
+	default:
+		if (e->error == -ETIMEDOUT ||
+		    e->error == -ETIME)
+			return;
+	case -ETIMEDOUT:
+	case -ETIME:
+		if (e->error == -ENOMEM ||
+		    e->error == -ENONET)
+			return;
+	case -ENOMEM:
+	case -ENONET:
+		if (e->error == -ERFKILL)
+			return;
+	case -ERFKILL:
+		if (e->error == -EADDRNOTAVAIL)
+			return;
+	case -EADDRNOTAVAIL:
+		if (e->error == -ENETUNREACH)
+			return;
+	case -ENETUNREACH:
+		if (e->error == -EHOSTUNREACH)
+			return;
+	case -EHOSTUNREACH:
+		if (e->error == -EHOSTDOWN)
+			return;
+	case -EHOSTDOWN:
+		if (e->error == -ECONNREFUSED)
+			return;
+	case -ECONNREFUSED:
+		if (e->error == -ECONNRESET)
+			return;
+	case -ECONNRESET: /* Responded, but call expired. */
+		if (e->responded)
+			return;
+		e->error = error;
+		return;
+
+	case -ECONNABORTED:
+		e->responded = true;
+		e->error = afs_abort_to_error(abort_code);
+		return;
+	}
+}