cifs: add attribute cache timeout (actimeo) tunable
Currently, the attribute cache timeout for CIFS is hardcoded to 1 second. This
means that the client might have to issue a QPATHINFO/QFILEINFO call every 1
second to verify if something has changes, which seems too expensive. On the
other hand, if the timeout is hardcoded to a higher value, workloads that
expect strict cache coherency might see unexpected results.
Making attribute cache timeout as a tunable will allow us to make a tradeoff
between performance and cache metadata correctness depending on the
application/workload needs.
Add 'actimeo' tunable that can be used to tune the attribute cache timeout.
The default timeout is set to 1 second. Also, display actimeo option value in
/proc/mounts.
It appears to me that 'actimeo' and the proposed (but not yet merged)
'strictcache' option cannot coexist, so care must be taken that we reset the
other option if one of them is set.
Changes since last post:
- fix option parsing and handle possible values correcly
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 32fa4d9..bb17ee2 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -105,6 +105,7 @@
unsigned int wsize;
bool sockopt_tcp_nodelay:1;
unsigned short int port;
+ unsigned long actimeo; /* attribute cache timeout (jiffies) */
char *prepath;
struct sockaddr_storage srcaddr; /* allow binding to a local IP */
struct nls_table *local_nls;
@@ -840,6 +841,8 @@
/* default to using server inode numbers where available */
vol->server_ino = 1;
+ vol->actimeo = CIFS_DEF_ACTIMEO;
+
if (!options)
return 1;
@@ -1214,6 +1217,16 @@
printk(KERN_WARNING "CIFS: server net"
"biosname longer than 15 truncated.\n");
}
+ } else if (strnicmp(data, "actimeo", 7) == 0) {
+ if (value && *value) {
+ vol->actimeo = HZ * simple_strtoul(value,
+ &value, 0);
+ if (vol->actimeo > CIFS_MAX_ACTIMEO) {
+ cERROR(1, "CIFS: attribute cache"
+ "timeout too large");
+ return 1;
+ }
+ }
} else if (strnicmp(data, "credentials", 4) == 0) {
/* ignore */
} else if (strnicmp(data, "version", 3) == 0) {
@@ -2571,6 +2584,8 @@
cFYI(1, "file mode: 0x%x dir mode: 0x%x",
cifs_sb->mnt_file_mode, cifs_sb->mnt_dir_mode);
+ cifs_sb->actimeo = pvolume_info->actimeo;
+
if (pvolume_info->noperm)
cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_NO_PERM;
if (pvolume_info->setuids)