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.
Changes since last post:
- fix an issue with signed overflow when using time_after()
- cache timeout stored internally in terms of jiffies for easier
handling
- update README about 'actimeo' option
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Suresh Jayaraman <sjayaraman@xxxxxxx>
---
fs/cifs/README | 9 +++++++++
fs/cifs/cifs_fs_sb.h | 1 +
fs/cifs/cifsfs.c | 2 ++
fs/cifs/cifsglob.h | 5 +++++
fs/cifs/connect.c | 10 ++++++++++
fs/cifs/inode.c | 7 ++++---
6 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/fs/cifs/README b/fs/cifs/README
index ee68d10..46af99a 100644
--- a/fs/cifs/README
+++ b/fs/cifs/README
@@ -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
diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index e9a393c..7852cd6 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -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;
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 9c37897..80fc16a 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -461,6 +461,8 @@ 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;
}
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index b577bf0..037f793 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -45,6 +45,11 @@
#define CIFS_MIN_RCV_POOL 4
/*
+ * default attribute cache timeout (seconds)
+ */
+#define CIFS_DEF_ACTIMEO (1)
+
+/*
* MAX_REQ is the maximum number of requests that WE will send
* on one socket concurrently. It also matches the most common
* value of max multiplex returned by servers. We may
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 251a17c..dfe1279 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -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;
@@ -1214,6 +1215,10 @@ 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 =
+ simple_strtoul(value, &value, 0) * HZ;
} else if (strnicmp(data, "credentials", 4) == 0) {
/* ignore */
} else if (strnicmp(data, "version", 3) == 0) {
@@ -2566,6 +2571,11 @@ 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);
+ if (pvolume_info->actimeo)
+ cifs_sb->actimeo = pvolume_info->actimeo;
+ else /* default */
+ cifs_sb->actimeo = CIFS_DEF_ACTIMEO * HZ;
+
if (pvolume_info->noperm)
cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_NO_PERM;
if (pvolume_info->setuids)
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index ff7d299..7571fbd 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -1648,6 +1648,7 @@ 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;
@@ -1658,12 +1659,12 @@ 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_open(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;
--
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