There is a scenario where a large number of discard commands are issued when the iscsi initiator connects to the target and then performs a session rescan operation. There is a time window, most of the commands are in UNMAP mode, and some discard commands become WRITE SAME with UNMAP. The discard mode has been negotiated during the SCSI probe. If the mode is temporarily changed from UNMAP to WRITE SAME with UNMAP, IO ERROR may occur because the target may not implement WRITE SAME with UNMAP. Keep the discard mode stable to fix this issue. Signed-off-by: Li Feng <fengli@xxxxxxxxxx> --- drivers/scsi/sd.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index f6c822c9cbd2..0165dc70a99b 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -2598,7 +2598,12 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp, if (buffer[14] & 0x40) /* LBPRZ */ sdkp->lbprz = 1; - sd_config_discard(sdkp, SD_LBP_WS16); + /* + * When the discard mode has been set to UNMAP, it should not be set to + * WRITE SAME with UNMAP. + */ + if (!sdkp->max_unmap_blocks) + sd_config_discard(sdkp, SD_LBP_WS16); } sdkp->capacity = lba + 1; -- 2.45.2
