From c8e639852ad720499912acedfd6b072325fd2807 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Tue, 7 Apr 2015 21:53:27 +0000 Subject: target: Fix COMPARE_AND_WRITE with SG_TO_MEM_NOALLOC handling This patch fixes a bug for COMPARE_AND_WRITE handling with fabrics using SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC. It adds the missing allocation for cmd->t_bidi_data_sg within transport_generic_new_cmd() that is used by COMPARE_AND_WRITE for the initial READ payload, even if the fabric is already providing a pre-allocated buffer for cmd->t_data_sg. Also, fix zero-length COMPARE_AND_WRITE handling within the compare_and_write_callback() and target_complete_ok_work() to queue the response, skipping the initial READ. This fixes COMPARE_AND_WRITE emulation with loopback, vhost, and xen-backend fabric drivers using SG_TO_MEM_NOALLOC. Reported-by: Christoph Hellwig Cc: Christoph Hellwig Cc: # v3.12+ Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_sbc.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'drivers/target/target_core_sbc.c') diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 315ff641408b..0064ffe9a219 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -321,7 +321,7 @@ sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *o return 0; } -static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd) +static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success) { unsigned char *buf, *addr; struct scatterlist *sg; @@ -385,7 +385,7 @@ sbc_execute_rw(struct se_cmd *cmd) cmd->data_direction); } -static sense_reason_t compare_and_write_post(struct se_cmd *cmd) +static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success) { struct se_device *dev = cmd->se_dev; @@ -408,7 +408,7 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd) return TCM_NO_SENSE; } -static sense_reason_t compare_and_write_callback(struct se_cmd *cmd) +static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success) { struct se_device *dev = cmd->se_dev; struct scatterlist *write_sg = NULL, *sg; @@ -423,10 +423,15 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd) /* * Handle early failure in transport_generic_request_failure(), - * which will not have taken ->caw_mutex yet.. + * which will not have taken ->caw_sem yet.. */ - if (!cmd->t_data_sg || !cmd->t_bidi_data_sg) + if (!success && (!cmd->t_data_sg || !cmd->t_bidi_data_sg)) return TCM_NO_SENSE; + /* + * Handle special case for zero-length COMPARE_AND_WRITE + */ + if (!cmd->data_length) + goto out; /* * Immediately exit + release dev->caw_sem if command has already * been failed with a non-zero SCSI status. -- cgit v1.2.3