Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 157/917] cifs: set a minimum of 120s for next dns resolution | Date | Mon, 15 Nov 2021 17:54:12 +0100 |
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From: Paulo Alcantara <pc@cjr.nz>
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@vger.kernel.org Fixes: 506c1da44fee ("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- 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 @@ -74,7 +74,8 @@ #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 @@ -115,7 +115,7 @@ 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;
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