On Wed, 2013-01-30 at 15:39 +0800, Asias He wrote: > On 01/30/2013 02:57 PM, Nicholas A. Bellinger wrote: > > From: Nicholas Bellinger <n...@linux-iscsi.org> > > > > This patch allows IBLOCK to check block hints in request_queue->flush_flags > > when reporting current backend device WriteCacheEnabled status to a remote > > SCSI initiator port. > > > > This is done via a se_subsystem_api->get_write_cache() call instead of a > > backend se_device creation time flag, as we expect REQ_FLUSH bits to > > possibly > > change from an underlying blk_queue_flush() by the SCSI disk driver, or > > internal raw struct block_device driver usage. > > > > Also go ahead and update iblock_execute_rw() bio I/O path code to use > > REQ_FLUSH + REQ_FUA hints when determining WRITE_FUA usage, and make SPC > > emulation code use a spc_check_dev_wce() helper to handle both types of > > cases for virtual backend subsystem drivers. > > > > Reported-by: majianpeng <majianp...@gmail.com> > > Cc: majianpeng <majianp...@gmail.com> > > Cc: Christoph Hellwig <h...@infradead.org> > > Cc: Jens Axboe <ax...@kernel.dk> > > Cc: James Bottomley <jbottom...@parallels.com> > > Signed-off-by: Nicholas Bellinger <n...@linux-iscsi.org> > > --- > > drivers/target/target_core_device.c | 6 ++++++ > > drivers/target/target_core_iblock.c | 31 +++++++++++++++++++++++-------- > > drivers/target/target_core_spc.c | 21 ++++++++++++++++++--- > > include/target/target_core_backend.h | 1 + > > 4 files changed, 48 insertions(+), 11 deletions(-) > > > > diff --git a/drivers/target/target_core_device.c > > b/drivers/target/target_core_device.c > > index e269510..1d71930 100644 > > --- a/drivers/target/target_core_device.c > > +++ b/drivers/target/target_core_device.c > > @@ -772,6 +772,12 @@ int se_dev_set_emulate_write_cache(struct se_device > > *dev, int flag) > > pr_err("emulate_write_cache not supported for pSCSI\n"); > > return -EINVAL; > > } > > + if (dev->transport->get_write_cache != NULL) { > > one nit: > > if (dev->transport->get_write_cache) { > > ?
Dropping extra NULL comparison here. > > > + pr_warn("emulate_write_cache cannot be changed when underlying" > > + " HW reports WriteCacheEnabled, ignoring request\n"); > > + return 0; > > + } > > + > > dev->dev_attrib.emulate_write_cache = flag; > > pr_debug("dev[%p]: SE Device WRITE_CACHE_EMULATION flag: %d\n", > > dev, dev->dev_attrib.emulate_write_cache); > > diff --git a/drivers/target/target_core_iblock.c > > b/drivers/target/target_core_iblock.c > > index b526d23..fc45683 100644 > > --- a/drivers/target/target_core_iblock.c > > +++ b/drivers/target/target_core_iblock.c > > @@ -154,6 +154,7 @@ static int iblock_configure_device(struct se_device > > *dev) > > > > if (blk_queue_nonrot(q)) > > dev->dev_attrib.is_nonrot = 1; > > + > > return 0; > > > > out_free_bioset: > > @@ -654,20 +655,24 @@ iblock_execute_rw(struct se_cmd *cmd) > > u32 sg_num = sgl_nents; > > sector_t block_lba; > > unsigned bio_cnt; > > - int rw; > > + int rw = 0; > > int i; > > > > if (data_direction == DMA_TO_DEVICE) { > > + struct iblock_dev *ib_dev = IBLOCK_DEV(dev); > > + struct request_queue *q = bdev_get_queue(ib_dev->ibd_bd); > > /* > > - * Force data to disk if we pretend to not have a volatile > > - * write cache, or the initiator set the Force Unit Access bit. > > + * Force writethrough using WRITE_FUA if a volatile write cache > > + * is not enabled, or if initiator set the Force Unit Access > > bit. > > */ > > - if (dev->dev_attrib.emulate_write_cache == 0 || > > - (dev->dev_attrib.emulate_fua_write > 0 && > > - (cmd->se_cmd_flags & SCF_FUA))) > > - rw = WRITE_FUA; > > - else > > + if (q->flush_flags & REQ_FUA) { > > + if (cmd->se_cmd_flags & SCF_FUA) > > + rw = WRITE_FUA; > > + else if (!(q->flush_flags & REQ_FLUSH)) > > + rw = WRITE_FUA; > > + } else { > > rw = WRITE; > > + } > > } else { > > rw = READ; > > } > > @@ -774,6 +779,15 @@ iblock_parse_cdb(struct se_cmd *cmd) > > return sbc_parse_cdb(cmd, &iblock_sbc_ops); > > } > > > > +bool iblock_get_write_cache(struct se_device *dev) > > +{ > > + struct iblock_dev *ib_dev = IBLOCK_DEV(dev); > > + struct block_device *bd = ib_dev->ibd_bd; > > + struct request_queue *q = bdev_get_queue(bd); > > + > > + return (q->flush_flags & REQ_FLUSH); > > no need of the (). > Dropping unnecessary () for bit-wise comparison. Thanks Asias! --nab > > +} > > + > > static struct se_subsystem_api iblock_template = { > > .name = "iblock", > > .inquiry_prod = "IBLOCK", > > @@ -790,6 +804,7 @@ static struct se_subsystem_api iblock_template = { > > .show_configfs_dev_params = iblock_show_configfs_dev_params, > > .get_device_type = sbc_get_device_type, > > .get_blocks = iblock_get_blocks, > > + .get_write_cache = iblock_get_write_cache, > > }; > > > > static int __init iblock_module_init(void) > > diff --git a/drivers/target/target_core_spc.c > > b/drivers/target/target_core_spc.c > > index 1346f8a..db6d003 100644 > > --- a/drivers/target/target_core_spc.c > > +++ b/drivers/target/target_core_spc.c > > @@ -407,16 +407,31 @@ check_scsi_name: > > } > > EXPORT_SYMBOL(spc_emulate_evpd_83); > > > > +static bool > > +spc_check_dev_wce(struct se_device *dev) > > +{ > > + bool wce = false; > > + > > + if (dev->transport->get_write_cache) > > + wce = dev->transport->get_write_cache(dev); > > + else if (dev->dev_attrib.emulate_write_cache > 0) > > + wce = true; > > + > > + return wce; > > +} > > + > > /* Extended INQUIRY Data VPD Page */ > > static sense_reason_t > > spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf) > > { > > + struct se_device *dev = cmd->se_dev; > > + > > buf[3] = 0x3c; > > /* Set HEADSUP, ORDSUP, SIMPSUP */ > > buf[5] = 0x07; > > > > /* If WriteCache emulation is enabled, set V_SUP */ > > - if (cmd->se_dev->dev_attrib.emulate_write_cache > 0) > > + if (spc_check_dev_wce(dev)) > > buf[6] = 0x01; > > return 0; > > } > > @@ -767,7 +782,7 @@ static int spc_modesense_caching(struct se_device *dev, > > u8 pc, u8 *p) > > if (pc == 1) > > goto out; > > > > - if (dev->dev_attrib.emulate_write_cache > 0) > > + if (spc_check_dev_wce(dev)) > > p[2] = 0x04; /* Write Cache Enable */ > > p[12] = 0x20; /* Disabled Read Ahead */ > > > > @@ -897,7 +912,7 @@ static sense_reason_t spc_emulate_modesense(struct > > se_cmd *cmd) > > (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY))) > > spc_modesense_write_protect(&buf[length], type); > > > > - if ((dev->dev_attrib.emulate_write_cache > 0) && > > + if ((spc_check_dev_wce(dev)) && > > (dev->dev_attrib.emulate_fua_write > 0)) > > spc_modesense_dpofua(&buf[length], type); > > > > diff --git a/include/target/target_core_backend.h > > b/include/target/target_core_backend.h > > index 819b0fc..f9a8016 100644 > > --- a/include/target/target_core_backend.h > > +++ b/include/target/target_core_backend.h > > @@ -35,6 +35,7 @@ struct se_subsystem_api { > > u32 (*get_device_type)(struct se_device *); > > sector_t (*get_blocks)(struct se_device *); > > unsigned char *(*get_sense_buffer)(struct se_cmd *); > > + bool (*get_write_cache)(struct se_device *); > > }; > > > > struct sbc_ops { > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html