Why is "fsc" (in particular caching of reads, to file, for oplocked
files) mutually exclusive with "strictcache" (write through of
non-oplocked files).
On Fri, Apr 27, 2012 at 5:56 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> Currently, we have several mount options that control cifs' cache
> behavior, but those options aren't considered to be mutually exclusive.
> The result is poorly-defined when someone specifies more than one of
> these options at mont time.
>
> Fix this by adding a new cache= mount option that will supercede "fsc",
> "strictcache", and "forcedirectio". That will help make it clear that
> these options are mutually exclusive. Also, change the legacy options to
> be mutually exclusive too, to ensure that users don't get surprises.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/cifs/connect.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 files changed, 71 insertions(+), 3 deletions(-)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index f31dc9a..de967dc 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -102,7 +102,7 @@ enum {
> Opt_srcaddr, Opt_prefixpath,
> Opt_iocharset, Opt_sockopt,
> Opt_netbiosname, Opt_servern,
> - Opt_ver, Opt_sec,
> + Opt_ver, Opt_sec, Opt_cache,
>
> /* Mount options to be ignored */
> Opt_ignore,
> @@ -212,6 +212,7 @@ static const match_table_t cifs_mount_option_tokens = {
> { Opt_ver, "vers=%s" },
> { Opt_ver, "version=%s" },
> { Opt_sec, "sec=%s" },
> + { Opt_cache, "cache=%s" },
>
> { Opt_ignore, "cred" },
> { Opt_ignore, "credentials" },
> @@ -258,6 +259,23 @@ static const match_table_t cifs_secflavor_tokens = {
> { Opt_sec_err, NULL }
> };
>
> +/* cache flavors */
> +enum {
> + Opt_cache_fsc,
> + Opt_cache_loose,
> + Opt_cache_strict,
> + Opt_cache_none,
> + Opt_cache_err
> +};
> +
> +static const match_table_t cifs_cacheflavor_tokens = {
> + { Opt_cache_fsc, "fsc" },
> + { Opt_cache_loose, "loose" },
> + { Opt_cache_strict, "strict" },
> + { Opt_cache_none, "none" },
> + { Opt_cache_err, NULL }
> +};
> +
> static int ip_connect(struct TCP_Server_Info *server);
> static int generic_ip_connect(struct TCP_Server_Info *server);
> static void tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink);
> @@ -1183,6 +1201,42 @@ static int cifs_parse_security_flavors(char *value,
> }
>
> static int
> +cifs_parse_cache_flavor(char *value, struct smb_vol *vol)
> +{
> + substring_t args[MAX_OPT_ARGS];
> +
> + switch (match_token(value, cifs_cacheflavor_tokens, args)) {
> + case Opt_cache_fsc:
> +#ifndef CONFIG_CIFS_FSCACHE
> + cERROR(1, "cache=fsc support requires that the kernel be "
> + "built with CONFIG_CIFS_FSCACHE enabled.");
> + return 1;
> +#endif
> + vol->direct_io = false;
> + vol->strict_io = false;
> + vol->fsc = true;
> + case Opt_cache_loose:
> + vol->direct_io = false;
> + vol->strict_io = false;
> + vol->fsc = false;
> + case Opt_cache_strict:
> + vol->direct_io = false;
> + vol->strict_io = true;
> + vol->fsc = false;
> + break;
> + case Opt_cache_none:
> + vol->direct_io = true;
> + vol->strict_io = false;
> + vol->fsc = false;
> + break;
> + default:
> + cERROR(1, "bad cache= option: %s", value);
> + return 1;
> + }
> + return 0;
> +}
> +
> +static int
> cifs_parse_mount_options(const char *mountdata, const char *devname,
> struct smb_vol *vol)
> {
> @@ -1411,10 +1465,14 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
> vol->seal = 1;
> break;
> case Opt_direct:
> - vol->direct_io = 1;
> + vol->fsc = false;
> + vol->direct_io = true;
> + vol->strict_io = false;
> break;
> case Opt_strictcache:
> - vol->strict_io = 1;
> + vol->fsc = false;
> + vol->direct_io = false;
> + vol->strict_io = true;
> break;
> case Opt_noac:
> printk(KERN_WARNING "CIFS: Mount option noac not "
> @@ -1428,6 +1486,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
> goto cifs_parse_mount_err;
> #endif
> vol->fsc = true;
> + vol->direct_io = false;
> + vol->strict_io = false;
> break;
> case Opt_mfsymlinks:
> vol->mfsymlinks = true;
> @@ -1835,6 +1895,14 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
> if (cifs_parse_security_flavors(string, vol) != 0)
> goto cifs_parse_mount_err;
> break;
> + case Opt_cache:
> + string = match_strdup(args);
> + if (string == NULL)
> + goto out_nomem;
> +
> + if (cifs_parse_cache_flavor(string, vol) != 0)
> + goto cifs_parse_mount_err;
> + break;
> default:
> /*
> * An option we don't recognize. Save it off for later
> --
> 1.7.7.6
>
--
Thanks,
Steve
--
To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
