From e10624f8c09710b3b0740ea3847627ea02f55c39 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 6 Jan 2016 12:03:41 -0800 Subject: [PATCH] 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: [] page_endio+0x1e/0x60 [] mpage_end_io+0x39/0x60 [] bio_endio+0x3f/0x60 [] pmem_make_request+0x111/0x230 [nd_pmem] ...i.e. unlock a page that was already unlocked via pmem_rw_page() => page_endio(). Reported-by: Vishal Verma Signed-off-by: Dan Williams --- drivers/nvdimm/pmem.c | 46 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 39 insertions(+), 7 deletions(-) diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 2b1f300..d00c659 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -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(); - page_endio(page, rw & WRITE, 0); - return 0; + /* + * 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 rc; } static long pmem_direct_access(struct block_device *bdev, sector_t sector, -- 2.7.4