Commit c8e63985 authored by Nicholas Bellinger's avatar Nicholas Bellinger

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: default avatarChristoph Hellwig <hch@lst.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org> # v3.12+
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 9ac8928e
......@@ -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.
......
......@@ -1647,11 +1647,11 @@ void transport_generic_request_failure(struct se_cmd *cmd,
transport_complete_task_attr(cmd);
/*
* Handle special case for COMPARE_AND_WRITE failure, where the
* callback is expected to drop the per device ->caw_mutex.
* callback is expected to drop the per device ->caw_sem.
*/
if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
cmd->transport_complete_callback)
cmd->transport_complete_callback(cmd);
cmd->transport_complete_callback(cmd, false);
switch (sense_reason) {
case TCM_NON_EXISTENT_LUN:
......@@ -2048,8 +2048,12 @@ static void target_complete_ok_work(struct work_struct *work)
if (cmd->transport_complete_callback) {
sense_reason_t rc;
rc = cmd->transport_complete_callback(cmd);
rc = cmd->transport_complete_callback(cmd, true);
if (!rc && !(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE_POST)) {
if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
!cmd->data_length)
goto queue_rsp;
return;
} else if (rc) {
ret = transport_send_check_condition_and_sense(cmd,
......@@ -2063,6 +2067,7 @@ static void target_complete_ok_work(struct work_struct *work)
}
}
queue_rsp:
switch (cmd->data_direction) {
case DMA_FROM_DEVICE:
spin_lock(&cmd->se_lun->lun_sep_lock);
......@@ -2166,6 +2171,16 @@ static inline void transport_reset_sgl_orig(struct se_cmd *cmd)
static inline void transport_free_pages(struct se_cmd *cmd)
{
if (cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC) {
/*
* Release special case READ buffer payload required for
* SG_TO_MEM_NOALLOC to function with COMPARE_AND_WRITE
*/
if (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) {
transport_free_sgl(cmd->t_bidi_data_sg,
cmd->t_bidi_data_nents);
cmd->t_bidi_data_sg = NULL;
cmd->t_bidi_data_nents = 0;
}
transport_reset_sgl_orig(cmd);
return;
}
......@@ -2318,6 +2333,7 @@ sense_reason_t
transport_generic_new_cmd(struct se_cmd *cmd)
{
int ret = 0;
bool zero_flag = !(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB);
/*
* Determine is the TCM fabric module has already allocated physical
......@@ -2326,7 +2342,6 @@ transport_generic_new_cmd(struct se_cmd *cmd)
*/
if (!(cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC) &&
cmd->data_length) {
bool zero_flag = !(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB);
if ((cmd->se_cmd_flags & SCF_BIDI) ||
(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE)) {
......@@ -2357,6 +2372,20 @@ transport_generic_new_cmd(struct se_cmd *cmd)
cmd->data_length, zero_flag);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
} else if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
cmd->data_length) {
/*
* Special case for COMPARE_AND_WRITE with fabrics
* using SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC.
*/
u32 caw_length = cmd->t_task_nolb *
cmd->se_dev->dev_attrib.block_size;
ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
&cmd->t_bidi_data_nents,
caw_length, zero_flag);
if (ret < 0)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
/*
* If this command is not a write we can execute it right here,
......
......@@ -523,7 +523,7 @@ struct se_cmd {
sense_reason_t (*execute_cmd)(struct se_cmd *);
sense_reason_t (*execute_rw)(struct se_cmd *, struct scatterlist *,
u32, enum dma_data_direction);
sense_reason_t (*transport_complete_callback)(struct se_cmd *);
sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool);
unsigned char *t_task_cdb;
unsigned char __t_task_cdb[TCM_MAX_COMMAND_SIZE];
......
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