This is a note to let you know that I've just added the patch titled
cifs: set a minimum of 120s for next dns resolution
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-set-a-minimum-of-120s-for-next-dns-resolution.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4ac0536f8874a903a72bddc57eb88db774261e3a Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@xxxxxx>
Date: Thu, 4 Nov 2021 13:13:28 -0300
Subject: cifs: set a minimum of 120s for next dns resolution
From: Paulo Alcantara <pc@xxxxxx>
commit 4ac0536f8874a903a72bddc57eb88db774261e3a upstream.
With commit 506c1da44fee ("cifs: use the expiry output of dns_query to
schedule next resolution") and after triggering the first reconnect,
the next async dns resolution of tcp server's hostname would be
scheduled based on dns_resolver's key expiry default, which happens to
default to 5s on most systems that use key.dns_resolver for upcall.
As per key.dns_resolver.conf(5):
default_ttl=<number>
The number of seconds to set as the expiration on a cached
record. This will be overridden if the program manages to re-
trieve TTL information along with the addresses (if, for exam-
ple, it accesses the DNS directly). The default is 5 seconds.
The value must be in the range 1 to INT_MAX.
Make the next async dns resolution no shorter than 120s as we do not
want to be upcalling too often.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 506c1da44fee ("cifs: use the expiry output of dns_query to schedule next resolution")
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxx>
Reviewed-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/cifsglob.h | 3 ++-
fs/cifs/connect.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -75,7 +75,8 @@
#define SMB_ECHO_INTERVAL_MAX 600
#define SMB_ECHO_INTERVAL_DEFAULT 60
-/* dns resolution interval in seconds */
+/* dns resolution intervals in seconds */
+#define SMB_DNS_RESOLVE_INTERVAL_MIN 120
#define SMB_DNS_RESOLVE_INTERVAL_DEFAULT 600
/* maximum number of PDUs in one compound */
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -116,7 +116,7 @@ static int reconn_set_ipaddr_from_hostna
* To make sure we don't use the cached entry, retry 1s
* after expiry.
*/
- ttl = (expiry - now + 1);
+ ttl = max_t(unsigned long, expiry - now, SMB_DNS_RESOLVE_INTERVAL_MIN) + 1;
}
rc = !rc ? -1 : 0;
Patches currently in stable-queue which might be from pc@xxxxxx are
queue-5.14/cifs-set-a-minimum-of-120s-for-next-dns-resolution.patch
