On Wed, 17 Nov 2010 23:53:34 +0530 Suresh Jayaraman <[email protected]> wrote:
> 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. > > Cc: Jeff Layton <[email protected]> > Signed-off-by: Suresh Jayaraman <[email protected]> > --- > fs/cifs/cifs_fs_sb.h | 1 + > fs/cifs/cifsfs.c | 1 + > fs/cifs/cifsglob.h | 5 +++++ > fs/cifs/connect.c | 10 ++++++++++ > fs/cifs/inode.c | 6 +++--- > 5 files changed, 20 insertions(+), 3 deletions(-) > > diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h > index e9a393c..efd2d73 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 int actimeo; > 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..13be23d 100644 > --- a/fs/cifs/cifsfs.c > +++ b/fs/cifs/cifsfs.c > @@ -461,6 +461,7 @@ 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); > + seq_printf(s, ",actimeo=%d", cifs_sb->actimeo); > > 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..7f92328 100644 > --- a/fs/cifs/connect.c > +++ b/fs/cifs/connect.c > @@ -103,6 +103,7 @@ struct smb_vol { > bool multiuser:1; > unsigned int rsize; > unsigned int wsize; > + unsigned int actimeo; /* attribute cache timeout */ > bool sockopt_tcp_nodelay:1; > unsigned short int port; > char *prepath; > @@ -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); > } 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; > + > 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..f30700d 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 +1659,11 @@ 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_after_eq(jiffies, cifs_i->time + (cifs_sb->actimeo * HZ))) Problem: Suppose (cifs_i->time + (cifs_sb->actimeo * HZ)) carries you past two sign bit changes. At that point, it may look like the resulting time is in the past, not the future. You actually do need to impose a limit here. I suggest looking very closely at time_before/time_after macros. It'll also be easier to deal storing actimeo in terms of jiffies instead of seconds. Finally, this value needs to be displayed in /proc/mounts. > 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; > -- Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
