On 08/29/2018 03:36 PM, Greg Edwards wrote: > When T10 PI is enabled on a backing device for the iblock backstore, the > PI SGL for the entire command is attached to the first bio only. This > works fine if the command is covered by a single bio, but can result in > ref tag errors in the client for the other bios in a multi-bio command, > e.g. > > [ 47.631236] sda: ref tag error at location 2048 (rcvd 0) > [ 47.637658] sda: ref tag error at location 4096 (rcvd 0) > [ 47.644228] sda: ref tag error at location 6144 (rcvd 0) > > The command will be split into multiple bios if the number of data SG > elements exceeds BIO_MAX_PAGES (see iblock_get_bio()). > > The bios may later be split again in the block layer on the host after > iblock_submit_bios(), depending on the queue limits of the backing > device. The block and SCSI layers will pass through the whole PI SGL > down to the LLDD however that first bio is split up, but the LLDD may > only use the portion that corresponds to the data length (depends on the > LLDD, tested with scsi_debug). > > Split the PI SGL across the bios in the command, so each bio's > bio_integrity_payload contains the protection information for the data > in the bio. Use an sg_mapping_iter to keep track of where we are in PI > SGL, so we know where to start with the next bio. > > Signed-off-by: Greg Edwards <[email protected]> > --- > Changes v1 -> v2: > * expand commit message > * use an sg_mapping_iter to track where we are in the PI SGL > > > drivers/target/target_core_iblock.c | 51 ++++++++++++++++++++--------- > 1 file changed, 35 insertions(+), 16 deletions(-) > > diff --git a/drivers/target/target_core_iblock.c > b/drivers/target/target_core_iblock.c > index ce1321a5cb7b..9f9c3c934ce1 100644 > --- a/drivers/target/target_core_iblock.c > +++ b/drivers/target/target_core_iblock.c > @@ -635,14 +635,15 @@ static ssize_t iblock_show_configfs_dev_params(struct > se_device *dev, char *b) > } > > static int > -iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio) > +iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio, > + struct sg_mapping_iter *miter) > { > struct se_device *dev = cmd->se_dev; > struct blk_integrity *bi; > struct bio_integrity_payload *bip; > struct iblock_dev *ib_dev = IBLOCK_DEV(dev); > - struct scatterlist *sg; > - int i, rc; > + int rc; > + size_t resid, len; > > bi = bdev_get_integrity(ib_dev->ibd_bd); > if (!bi) { > @@ -656,25 +657,32 @@ iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio) > return PTR_ERR(bip); > }
Can you still hit the issue where t_prot_nents > BIO_MAX_PAGES so bio_integrity_alloc fails or is t_prot_nents always going to be smaller. Was wondering why you dropped that from the last patch.
