The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 4134455f2aafdfeab50cabb4cccb35e916034b93 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka mpatocka@redhat.com Date: Tue, 9 Feb 2021 10:56:20 -0500 Subject: [PATCH] dm writecache: fix writing beyond end of underlying device when shrinking
Do not attempt to write any data beyond the end of the underlying data device while shrinking it.
The DM writecache device must be suspended when the underlying data device is shrunk.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index e8382d73c73c..baf5a9ce2b25 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -148,6 +148,7 @@ struct dm_writecache { size_t metadata_sectors; size_t n_blocks; uint64_t seq_count; + sector_t data_device_sectors; void *block_start; struct wc_entry *entries; unsigned block_size; @@ -977,6 +978,8 @@ static void writecache_resume(struct dm_target *ti)
wc_lock(wc);
+ wc->data_device_sectors = i_size_read(wc->dev->bdev->bd_inode) >> SECTOR_SHIFT; + if (WC_MODE_PMEM(wc)) { persistent_memory_invalidate_cache(wc->memory_map, wc->memory_map_size); } else { @@ -1646,6 +1649,10 @@ static bool wc_add_block(struct writeback_struct *wb, struct wc_entry *e, gfp_t void *address = memory_data(wc, e);
persistent_memory_flush_cache(address, block_size); + + if (unlikely(bio_end_sector(&wb->bio) >= wc->data_device_sectors)) + return true; + return bio_add_page(&wb->bio, persistent_memory_page(address), block_size, persistent_memory_page_offset(address)) != 0; } @@ -1717,6 +1724,9 @@ static void __writecache_writeback_pmem(struct dm_writecache *wc, struct writeba if (writecache_has_error(wc)) { bio->bi_status = BLK_STS_IOERR; bio_endio(bio); + } else if (unlikely(!bio_sectors(bio))) { + bio->bi_status = BLK_STS_OK; + bio_endio(bio); } else { submit_bio(bio); } @@ -1760,6 +1770,14 @@ static void __writecache_writeback_ssd(struct dm_writecache *wc, struct writebac e = f; }
+ if (unlikely(to.sector + to.count > wc->data_device_sectors)) { + if (to.sector >= wc->data_device_sectors) { + writecache_copy_endio(0, 0, c); + continue; + } + from.count = to.count = wc->data_device_sectors - to.sector; + } + dm_kcopyd_copy(wc->dm_kcopyd, &from, 1, &to, 0, writecache_copy_endio, c);
__writeback_throttle(wc, wbl);