Commit e10624f8 authored by Dan Williams's avatar Dan Williams
Browse files

pmem: fail io-requests to known bad blocks 



Check the sectors specified in a read bio to see if they hit a known bad
block, and return an error code pmem_do_bvec().

Note that the ->rw_page() is not in a position to return errors.  For
now, copy the same layering violation present in zram_rw_page() to avoid
crashes of the form:

 kernel BUG at mm/filemap.c:822!
 [..]
 Call Trace:
  [<ffffffff811c540e>] page_endio+0x1e/0x60
  [<ffffffff81290d29>] mpage_end_io+0x39/0x60
  [<ffffffff8141c4ef>] bio_endio+0x3f/0x60
  [<ffffffffa005c491>] pmem_make_request+0x111/0x230 [nd_pmem]

...i.e. unlock a page that was already unlocked via pmem_rw_page() =>
page_endio().

Reported-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent b95f5f43

drivers/nvdimm/pmem.c

+39 −7
Original line number Diff line number Diff line
@@ -47,7 +47,20 @@ struct pmem_device { 


static int pmem_major;



static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,

static bool is_bad_pmem(struct badblocks *bb, sector_t sector, unsigned int len)

{

	if (bb->count) {

		sector_t first_bad;

		int num_bad;



		return !!badblocks_check(bb, sector, len / 512, &first_bad,

				&num_bad);

	}



	return false;

}



static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,

			unsigned int len, unsigned int off, int rw,

			sector_t sector)

{
@@ -56,6 +69,8 @@ static void pmem_do_bvec(struct pmem_device *pmem, struct page *page, 
	void __pmem *pmem_addr = pmem->virt_addr + pmem_off;



	if (rw == READ) {

		if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))

			return -EIO;

		memcpy_from_pmem(mem + off, pmem_addr, len);

		flush_dcache_page(page);

	} else {
@@ -64,10 +79,12 @@ static void pmem_do_bvec(struct pmem_device *pmem, struct page *page, 
	}



	kunmap_atomic(mem);

	return 0;

}



static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)

{

	int rc = 0;

	bool do_acct;

	unsigned long start;

	struct bio_vec bvec;
@@ -76,9 +93,15 @@ static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio) 
	struct pmem_device *pmem = bdev->bd_disk->private_data;



	do_acct = nd_iostat_start(bio, &start);

	bio_for_each_segment(bvec, bio, iter)

		pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len, bvec.bv_offset,

				bio_data_dir(bio), iter.bi_sector);

	bio_for_each_segment(bvec, bio, iter) {

		rc = pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len,

				bvec.bv_offset, bio_data_dir(bio),

				iter.bi_sector);

		if (rc) {

			bio->bi_error = rc;

			break;

		}

	}

	if (do_acct)

		nd_iostat_end(bio, start);
@@ -93,13 +116,22 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector, 
		       struct page *page, int rw)

{

	struct pmem_device *pmem = bdev->bd_disk->private_data;

	int rc;



	pmem_do_bvec(pmem, page, PAGE_CACHE_SIZE, 0, rw, sector);

	rc = pmem_do_bvec(pmem, page, PAGE_CACHE_SIZE, 0, rw, sector);

	if (rw & WRITE)

		wmb_pmem();



	/*

	 * The ->rw_page interface is subtle and tricky.  The core

	 * retries on any error, so we can only invoke page_endio() in

	 * the successful completion case.  Otherwise, we'll see crashes

	 * caused by double completion.

	 */

	if (rc == 0)

		page_endio(page, rw & WRITE, 0);



	return 0;

	return rc;

}



static long pmem_direct_access(struct block_device *bdev, sector_t sector,

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