From 4ac0536f8874a903a72bddc57eb88db774261e3a Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Thu, 4 Nov 2021 13:13:28 -0300 Subject: [PATCH] cifs: set a minimum of 120s for next dns resolution 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= 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@vger.kernel.org Fixes: 506c1da44fee ("cifs: use the expiry output of dns_query to schedule next resolution") Signed-off-by: Paulo Alcantara (SUSE) Reviewed-by: Shyam Prasad N Signed-off-by: Steve French --- fs/cifs/cifsglob.h | 3 ++- fs/cifs/connect.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 41e97df4e0e5..102a4a2b734d 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -76,7 +76,8 @@ #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 */ diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index f5c5731cda02..6278a90cb027 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -115,7 +115,7 @@ static int reconn_set_ipaddr_from_hostname(struct TCP_Server_Info *server) * 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; -- 2.11.0