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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>
This commit is contained in:
Suresh Jayaraman 2010-12-01 14:42:28 +05:30 committed by Steve French
parent 8cb280c90f
commit 6d20e8406f
6 changed files with 41 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
fs/cifs/README
View File

@ -337,6 +337,15 @@ A partial list of the supported mount options follows:
wsize default write size (default 57344)
maximum wsize currently allowed by CIFS is 57344 (fourteen
4096 byte pages)
actimeo=n attribute cache timeout in seconds (default 1 second).
After this timeout, the cifs client requests fresh attribute
information from the server. This option allows to tune the
attribute cache timeout to suit the workload needs. Shorter
timeouts mean better the cache coherency, but increased number
of calls to the server. Longer timeouts mean reduced number
of calls to the server at the expense of less stricter cache
coherency checks (i.e. incorrect attribute cache for a short
period of time).
rw mount the network share read-write (note that the
server may still consider the share read-only)
ro mount network share read-only

1
fs/cifs/cifs_fs_sb.h
View File

@ -48,6 +48,7 @@ struct cifs_sb_info {
struct nls_table *local_nls;
unsigned int rsize;
unsigned int wsize;
unsigned long actimeo; /* attribute cache timeout (jiffies) */
atomic_t active;
uid_t mnt_uid;
gid_t mnt_gid;

2
fs/cifs/cifsfs.c
View File

@ -463,6 +463,8 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)
seq_printf(s, ",rsize=%d", cifs_sb->rsize);
seq_printf(s, ",wsize=%d", cifs_sb->wsize);
/* convert actimeo and display it in seconds */
seq_printf(s, ",actimeo=%lu", cifs_sb->actimeo / HZ);
return 0;
}

10
fs/cifs/cifsglob.h
View File

@ -44,6 +44,16 @@
#define CIFS_MIN_RCV_POOL 4
/*
* default attribute cache timeout (jiffies)
*/
#define CIFS_DEF_ACTIMEO (1 * HZ)
/*
* max attribute cache timeout (jiffies) - 2^30
*/
#define CIFS_MAX_ACTIMEO (1 << 30)
/*
* MAX_REQ is the maximum number of requests that WE will send
* on one socket concurrently. It also matches the most common

15
fs/cifs/connect.c
View File

@ -105,6 +105,7 @@ struct smb_vol {
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 @@ cifs_parse_mount_options(char *options, const char *devname,
/* 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 @@ cifs_parse_mount_options(char *options, const char *devname,
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 @@ static void setup_cifs_sb(struct smb_vol *pvolume_info,
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)

7
fs/cifs/inode.c
View File

@ -1653,6 +1653,7 @@ static bool
cifs_inode_needs_reval(struct inode *inode)
{
struct cifsInodeInfo *cifs_i = CIFS_I(inode);
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
if (cifs_i->clientCanCacheRead)
return false;
@ -1663,12 +1664,12 @@ cifs_inode_needs_reval(struct inode *inode)
if (cifs_i->time == 0)
return true;
/* FIXME: the actimeo should be tunable */
if (time_after_eq(jiffies, cifs_i->time + HZ))
if (!time_in_range(jiffies, cifs_i->time,
cifs_i->time + cifs_sb->actimeo))
return true;
/* hardlinked files w/ noserverino get "special" treatment */
if (!(CIFS_SB(inode->i_sb)->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) &&
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) &&
S_ISREG(inode->i_mode) && inode->i_nlink != 1)
return true;