forked from luck/tmp_suning_uos_patched
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 <hch@lst.de> Cc: Christoph Hellwig <hch@lst.de> Cc: <stable@vger.kernel.org> # v3.12+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
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@ -321,7 +321,7 @@ sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *o
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return 0;
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}
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static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd)
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static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success)
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{
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unsigned char *buf, *addr;
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struct scatterlist *sg;
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@ -385,7 +385,7 @@ sbc_execute_rw(struct se_cmd *cmd)
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cmd->data_direction);
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}
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static sense_reason_t compare_and_write_post(struct se_cmd *cmd)
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static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success)
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{
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struct se_device *dev = cmd->se_dev;
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@ -408,7 +408,7 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd)
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return TCM_NO_SENSE;
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}
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static sense_reason_t compare_and_write_callback(struct se_cmd *cmd)
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static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success)
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{
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struct se_device *dev = cmd->se_dev;
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struct scatterlist *write_sg = NULL, *sg;
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@ -423,10 +423,15 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd)
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/*
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* Handle early failure in transport_generic_request_failure(),
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* which will not have taken ->caw_mutex yet..
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* which will not have taken ->caw_sem yet..
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*/
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if (!cmd->t_data_sg || !cmd->t_bidi_data_sg)
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if (!success && (!cmd->t_data_sg || !cmd->t_bidi_data_sg))
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return TCM_NO_SENSE;
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/*
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* Handle special case for zero-length COMPARE_AND_WRITE
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*/
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if (!cmd->data_length)
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goto out;
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/*
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* Immediately exit + release dev->caw_sem if command has already
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* been failed with a non-zero SCSI status.
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@ -1647,11 +1647,11 @@ void transport_generic_request_failure(struct se_cmd *cmd,
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transport_complete_task_attr(cmd);
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/*
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* Handle special case for COMPARE_AND_WRITE failure, where the
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* callback is expected to drop the per device ->caw_mutex.
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* callback is expected to drop the per device ->caw_sem.
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*/
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if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
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cmd->transport_complete_callback)
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cmd->transport_complete_callback(cmd);
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cmd->transport_complete_callback(cmd, false);
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switch (sense_reason) {
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case TCM_NON_EXISTENT_LUN:
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@ -2048,8 +2048,12 @@ static void target_complete_ok_work(struct work_struct *work)
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if (cmd->transport_complete_callback) {
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sense_reason_t rc;
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rc = cmd->transport_complete_callback(cmd);
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rc = cmd->transport_complete_callback(cmd, true);
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if (!rc && !(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE_POST)) {
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if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
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!cmd->data_length)
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goto queue_rsp;
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return;
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} else if (rc) {
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ret = transport_send_check_condition_and_sense(cmd,
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@ -2063,6 +2067,7 @@ static void target_complete_ok_work(struct work_struct *work)
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}
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}
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queue_rsp:
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switch (cmd->data_direction) {
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case DMA_FROM_DEVICE:
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spin_lock(&cmd->se_lun->lun_sep_lock);
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@ -2166,6 +2171,16 @@ static inline void transport_reset_sgl_orig(struct se_cmd *cmd)
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static inline void transport_free_pages(struct se_cmd *cmd)
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{
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if (cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC) {
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/*
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* Release special case READ buffer payload required for
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* SG_TO_MEM_NOALLOC to function with COMPARE_AND_WRITE
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*/
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if (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) {
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transport_free_sgl(cmd->t_bidi_data_sg,
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cmd->t_bidi_data_nents);
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cmd->t_bidi_data_sg = NULL;
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cmd->t_bidi_data_nents = 0;
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}
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transport_reset_sgl_orig(cmd);
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return;
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}
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@ -2318,6 +2333,7 @@ sense_reason_t
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transport_generic_new_cmd(struct se_cmd *cmd)
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{
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int ret = 0;
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bool zero_flag = !(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB);
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/*
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* Determine is the TCM fabric module has already allocated physical
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@ -2326,7 +2342,6 @@ transport_generic_new_cmd(struct se_cmd *cmd)
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*/
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if (!(cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC) &&
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cmd->data_length) {
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bool zero_flag = !(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB);
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if ((cmd->se_cmd_flags & SCF_BIDI) ||
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(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE)) {
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@ -2357,6 +2372,20 @@ transport_generic_new_cmd(struct se_cmd *cmd)
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cmd->data_length, zero_flag);
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if (ret < 0)
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return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
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} else if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
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cmd->data_length) {
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/*
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* Special case for COMPARE_AND_WRITE with fabrics
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* using SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC.
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*/
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u32 caw_length = cmd->t_task_nolb *
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cmd->se_dev->dev_attrib.block_size;
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ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
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&cmd->t_bidi_data_nents,
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caw_length, zero_flag);
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if (ret < 0)
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return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
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}
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/*
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* If this command is not a write we can execute it right here,
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@ -523,7 +523,7 @@ struct se_cmd {
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sense_reason_t (*execute_cmd)(struct se_cmd *);
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sense_reason_t (*execute_rw)(struct se_cmd *, struct scatterlist *,
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u32, enum dma_data_direction);
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sense_reason_t (*transport_complete_callback)(struct se_cmd *);
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sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool);
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unsigned char *t_task_cdb;
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unsigned char __t_task_cdb[TCM_MAX_COMMAND_SIZE];
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