add user friendly interface wce_rcd to enable/disable write&read cache. The code base on cache_type, but need short input.
enable both write and read cache: echo "10" > wce_rcd wce rcd write_cache read_cache 0 0 off on 0 1 off off 1 0 on on 1 1 on off Signed-off-by: weiping zhang <[email protected]> --- drivers/scsi/sd.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index a028ab3..9ab210c 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -139,6 +139,15 @@ static const char *sd_cache_types[] = { "write back, no read (daft)" }; +/* + * wce rcd write_cache read_cache + * 0 0 off on + * 0 1 off off + * 1 0 on on + * 1 1 on off + */ +static const char * const sd_wce_rcd[] = {"00", "01", "10", "11"}; + static void sd_set_flush_flag(struct scsi_disk *sdkp) { bool wc = false, fua = false; @@ -287,6 +296,80 @@ cache_type_show(struct device *dev, struct device_attribute *attr, char *buf) static DEVICE_ATTR_RW(cache_type); static ssize_t +wce_rcd_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + int ct, rcd, wce, sp; + struct scsi_disk *sdkp = to_scsi_disk(dev); + struct scsi_device *sdp = sdkp->device; + char buffer[64]; + char *buffer_data; + struct scsi_mode_data data; + struct scsi_sense_hdr sshdr; + static const char temp[] = "temp "; + int len; + + if (sdp->type != TYPE_DISK && sdp->type != TYPE_ZBC) + /* no cache control on RBC devices; theoretically they + * can do it, but there's probably so many exceptions + * it's not worth the risk + */ + return -EINVAL; + + if (strncmp(buf, temp, sizeof(temp) - 1) == 0) { + buf += sizeof(temp) - 1; + sdkp->cache_override = 1; + } else { + sdkp->cache_override = 0; + } + + ct = sysfs_match_string(sd_wce_rcd, buf); + if (ct < 0) + return -EINVAL; + + rcd = ct & 0x01 ? 1 : 0; + wce = (ct & 0x02) && !sdkp->write_prot ? 1 : 0; + + if (sdkp->cache_override) { + sdkp->WCE = wce; + sdkp->RCD = rcd; + sd_set_flush_flag(sdkp); + return count; + } + + if (scsi_mode_sense(sdp, 0x08, 8, buffer, sizeof(buffer), SD_TIMEOUT, + SD_MAX_RETRIES, &data, NULL)) + return -EINVAL; + len = min_t(size_t, sizeof(buffer), data.length - data.header_length - + data.block_descriptor_length); + buffer_data = buffer + data.header_length + + data.block_descriptor_length; + buffer_data[2] &= ~0x05; + buffer_data[2] |= wce << 2 | rcd; + sp = buffer_data[0] & 0x80 ? 1 : 0; + buffer_data[0] &= ~0x80; + + if (scsi_mode_select(sdp, 1, sp, 8, buffer_data, len, SD_TIMEOUT, + SD_MAX_RETRIES, &data, &sshdr)) { + if (scsi_sense_valid(&sshdr)) + sd_print_sense_hdr(sdkp, &sshdr); + return -EINVAL; + } + revalidate_disk(sdkp->disk); + return count; +} + +static ssize_t +wce_rcd_show(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct scsi_disk *sdkp = to_scsi_disk(dev); + int ct = sdkp->RCD + 2*sdkp->WCE; + + return sprintf(buf, "%s\n", sd_wce_rcd[ct]); +} +static DEVICE_ATTR_RW(wce_rcd); + +static ssize_t FUA_show(struct device *dev, struct device_attribute *attr, char *buf) { struct scsi_disk *sdkp = to_scsi_disk(dev); @@ -524,6 +607,7 @@ static DEVICE_ATTR_RW(max_write_same_blocks); static struct attribute *sd_disk_attrs[] = { &dev_attr_cache_type.attr, + &dev_attr_wce_rcd.attr, &dev_attr_FUA.attr, &dev_attr_allow_restart.attr, &dev_attr_manage_start_stop.attr, -- 2.9.4
