[PATCH v6 2/5] dax: enable dax in the presence of known media errors (badblocks)

Vishal Verma
2016-05-10T18:49:13Z

From: Dan Williams <dan.j.williams@intel.com>

1/ If a mapping overlaps a bad sector fail the request.

2/ Do not opportunistically report more dax-capable capacity than is
requested when errors present.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[vishal: fix a conflict with system RAM collision patches]
[vishal: add a 'size' parameter to ->direct_access]
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
arch/powerpc/sysdev/axonram.c | 2 +-
block/ioctl.c | 9 ---------
drivers/block/brd.c | 2 +-
drivers/nvdimm/pmem.c | 10 +++++++++-
drivers/s390/block/dcssblk.c | 2 +-
fs/block_dev.c | 2 +-
include/linux/blkdev.h | 2 +-
7 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index 0d112b9..ff75d70 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -143,7 +143,7 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
*/
static long
axon_ram_direct_access(struct block_device *device, sector_t sector,
- void __pmem **kaddr, pfn_t *pfn)
+ void __pmem **kaddr, pfn_t *pfn, long size)
{
struct axon_ram_bank *bank = device->bd_disk->private_data;
loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
diff --git a/block/ioctl.c b/block/ioctl.c
index 4ff1f92..bf80bfd 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -423,15 +423,6 @@ bool blkdev_dax_capable(struct block_device *bdev)
|| (bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
return false;

- /*
- * If the device has known bad blocks, force all I/O through the
- * driver / page cache.
- *
- * TODO: support finer grained dax error handling
- */
- if (disk->bb && disk->bb->count)
- return false;
-
return true;
}
#endif
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 51a071e..c04bd9b 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -381,7 +381,7 @@ static int brd_rw_page(struct block_device *bdev, sector_t sector,

#ifdef CONFIG_BLK_DEV_RAM_DAX
static long brd_direct_access(struct block_device *bdev, sector_t sector,
- void __pmem **kaddr, pfn_t *pfn)
+ void __pmem **kaddr, pfn_t *pfn, long size)
{
struct brd_device *brd = bdev->bd_disk->private_data;
struct page *page;
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index f798899..c447579 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -182,14 +182,22 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
}

static long pmem_direct_access(struct block_device *bdev, sector_t sector,
- void __pmem **kaddr, pfn_t *pfn)
+ void __pmem **kaddr, pfn_t *pfn, long size)
{
struct pmem_device *pmem = bdev->bd_disk->private_data;
resource_size_t offset = sector * 512 + pmem->data_offset;

+ if (unlikely(is_bad_pmem(&pmem->bb, sector, size)))
+ return -EIO;
*kaddr = pmem->virt_addr + offset;
*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);

+ /*
+ * If badblocks are present, limit known good range to the
+ * requested range.
+ */
+ if (unlikely(pmem->bb.count))
+ return size;
return pmem->size - pmem->pfn_pad - offset;
}

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index b839086..c45d538 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -884,7 +884,7 @@ fail:

static long
dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
- void __pmem **kaddr, pfn_t *pfn)
+ void __pmem **kaddr, pfn_t *pfn, long size)
{
struct dcssblk_dev_info *dev_info;
unsigned long offset, dev_sz;
diff --git a/fs/block_dev.c b/fs/block_dev.c
index b25bb23..02c68c4 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -488,7 +488,7 @@ long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
sector += get_start_sect(bdev);
if (sector % (PAGE_SIZE / 512))
return -EINVAL;
- avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn);
+ avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn, size);
if (!avail)
return -ERANGE;
if (avail > 0 && avail & ~PAGE_MASK)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 669e419..55ed530 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1657,7 +1657,7 @@ struct block_device_operations {
int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
long (*direct_access)(struct block_device *, sector_t, void __pmem **,
- pfn_t *);
+ pfn_t *, long);
unsigned int (*check_events) (struct gendisk *disk,
unsigned int clearing);
/* ->media_changed() is DEPRECATED, use ->check_events() instead */