| Message ID | 1447451209-30772-1-git-send-email-martin.petersen@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
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On Fri, 2015-11-13 at 16:46 -0500, Martin K. Petersen wrote: > A device may report an OPTIMAL UNMAP GRANULARITY and UNMAP > GRANULARITY > ALIGNMENT in the Block Limits VPD. These parameters describe the > device's internal provisioning allocation units. By default the block > layer will round and align any discard requests based on these > limits. > > If a device reports LBPRZ=1 to guarantee zeroes after discard, > however, > it is imperative that the block layer does not leave out any parts of > the requested block range. Otherwise the device can not do the > required > zeroing of any partial allocation units and this can lead to data > corruption. > > Since the dm thinp personality relies on the block layer's current > behavior and is unable to deal with partial discard blocks we work > around the problem by setting the granularity to match the logical > block > size when LBPRZ is enabled. > > Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> > --- > drivers/scsi/sd.c | 23 ++++++++++++++++++----- > 1 file changed, 18 insertions(+), 5 deletions(-) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index 3f370228bf31..c322969026bc 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -636,11 +636,24 @@ static void sd_config_discard(struct scsi_disk > *sdkp, unsigned int mode) > unsigned int max_blocks = 0; > > q->limits.discard_zeroes_data = 0; > - q->limits.discard_alignment = sdkp->unmap_alignment * > - logical_block_size; > - q->limits.discard_granularity = > - max(sdkp->physical_block_size, > - sdkp->unmap_granularity * logical_block_size); > + > + /* > + * When LBPRZ is reported, discard alignment and granularity > + * must be fixed to the logical block size. Otherwise the > block > + * layer will drop misaligned portions of the request which > can > + * lead to data corruption. If LBPRZ is not set, we honor > the > + * device preference. > + */ > + if (sdkp->lbprz) { > + q->limits.discard_alignment = 0; > + q->limits.discard_granularity = 1; > + } else { > + q->limits.discard_alignment = sdkp->unmap_alignment > * > + logical_block_size; > + q->limits.discard_granularity = > + max(sdkp->physical_block_size, > + sdkp->unmap_granularity * > logical_block_size); > + } > > sdkp->provisioning_mode = mode; > Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 3f370228bf31..c322969026bc 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -636,11 +636,24 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode) unsigned int max_blocks = 0; q->limits.discard_zeroes_data = 0; - q->limits.discard_alignment = sdkp->unmap_alignment * - logical_block_size; - q->limits.discard_granularity = - max(sdkp->physical_block_size, - sdkp->unmap_granularity * logical_block_size); + + /* + * When LBPRZ is reported, discard alignment and granularity + * must be fixed to the logical block size. Otherwise the block + * layer will drop misaligned portions of the request which can + * lead to data corruption. If LBPRZ is not set, we honor the + * device preference. + */ + if (sdkp->lbprz) { + q->limits.discard_alignment = 0; + q->limits.discard_granularity = 1; + } else { + q->limits.discard_alignment = sdkp->unmap_alignment * + logical_block_size; + q->limits.discard_granularity = + max(sdkp->physical_block_size, + sdkp->unmap_granularity * logical_block_size); + } sdkp->provisioning_mode = mode;
A device may report an OPTIMAL UNMAP GRANULARITY and UNMAP GRANULARITY ALIGNMENT in the Block Limits VPD. These parameters describe the device's internal provisioning allocation units. By default the block layer will round and align any discard requests based on these limits. If a device reports LBPRZ=1 to guarantee zeroes after discard, however, it is imperative that the block layer does not leave out any parts of the requested block range. Otherwise the device can not do the required zeroing of any partial allocation units and this can lead to data corruption. Since the dm thinp personality relies on the block layer's current behavior and is unable to deal with partial discard blocks we work around the problem by setting the granularity to match the logical block size when LBPRZ is enabled. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> --- drivers/scsi/sd.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)