From 9da8e0f4bbeb2dff0e3171987a21e3bf5e52fe5b Mon Sep 17 00:00:00 2001 From: Ivan Mironov Date: Sun, 23 Dec 2018 12:41:58 +0500 Subject: [PATCH] scsi: sd: Fix cache_type_store() commit 44759979a49bfd2d20d789add7fa81a21eb1a4ab upstream. Changing of caching mode via /sys/devices/.../scsi_disk/.../cache_type may fail if device responds to MODE SENSE command with DPOFUA flag set, and then checks this flag to be not set on MODE SELECT command. In this scenario, when trying to change cache_type, write always fails: # echo "none" >cache_type bash: echo: write error: Invalid argument And following appears in dmesg: [13007.865745] sd 1:0:1:0: [sda] Sense Key : Illegal Request [current] [13007.865753] sd 1:0:1:0: [sda] Add. Sense: Invalid field in parameter list From SBC-4 r15, 6.5.1 "Mode pages overview", description of DEVICE-SPECIFIC PARAMETER field in the mode parameter header: ... The write protect (WP) bit for mode data sent with a MODE SELECT command shall be ignored by the device server. ... The DPOFUA bit is reserved for mode data sent with a MODE SELECT command. ... The remaining bits in the DEVICE-SPECIFIC PARAMETER byte are also reserved and shall be set to zero. [mkp: shuffled commentary to commit description] Cc: stable@vger.kernel.org Signed-off-by: Ivan Mironov Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sd.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index ab999c4444b8..867ae76f93f2 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -208,6 +208,12 @@ cache_type_store(struct device *dev, struct device_attribute *attr, sp = buffer_data[0] & 0x80 ? 1 : 0; buffer_data[0] &= ~0x80; + /* + * Ensure WP, DPOFUA, and RESERVED fields are cleared in + * received mode parameter buffer before doing MODE SELECT. + */ + data.device_specific = 0; + if (scsi_mode_select(sdp, 1, sp, 8, buffer_data, len, SD_TIMEOUT, SD_MAX_RETRIES, &data, &sshdr)) { if (scsi_sense_valid(&sshdr)) -- 2.20.1