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cifs: set a minimum of 120s for next dns resolution 

With commit 506c1da44f ("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@vger.kernel.org
Fixes: 506c1da44f ("cifs: use the expiry output of dns_query to schedule next resolution")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2021-11-04 13:13:28 -03:00 committed by Steve French
parent bbcce36804
commit 4ac0536f88
2 changed files with 3 additions and 2 deletions
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3
fs/cifs/cifsglob.h
View File

@ -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 */

2
fs/cifs/connect.c
View File

@ -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;