On Mon, 1 Mar 2021, gregkh@linuxfoundation.org wrote:

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

Hi

This is backport of the patch 4134455f2aafdfeab50cabb4cccb35e916034b93 for the stable branch 4.19.

Mikulas

commit 4134455f2aafdfeab50cabb4cccb35e916034b93 Author: Mikulas Patocka mpatocka@redhat.com Date: Tue Feb 9 10:56:20 2021 -0500

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

--- drivers/md/dm-writecache.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)

Index: linux-stable/drivers/md/dm-writecache.c =================================================================== --- linux-stable.orig/drivers/md/dm-writecache.c 2021-07-18 21:05:45.000000000 +0200 +++ linux-stable/drivers/md/dm-writecache.c 2021-07-18 21:09:52.000000000 +0200 @@ -142,6 +142,7 @@ 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; @@ -929,6 +930,8 @@ static void writecache_resume(struct dm_

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 { @@ -1499,6 +1502,10 @@ static bool wc_add_block(struct writebac 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; } @@ -1571,6 +1578,9 @@ static void __writecache_writeback_pmem( if (writecache_has_error(wc)) { bio->bi_status = BLK_STS_IOERR; bio_endio(&wb->bio); + } else if (unlikely(!bio_sectors(&wb->bio))) { + bio->bi_status = BLK_STS_OK; + bio_endio(&wb->bio); } else { submit_bio(&wb->bio); } @@ -1614,6 +1624,14 @@ static void __writecache_writeback_ssd(s 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);