[dm-devel] [PATCH 1/2] dm-bufio: subtract the number of initial sectors in dm_bufio_get_device_size

[Milan Broz]

From: Mikulas Patocka <mpatocka at redhat.com>

dm_bufio_get_device_size returns returns the device size in blocks. Before
returning the value, we must subtract the nubmer of starting sectors. The
number of starting sectos may not be divisible by block size.

Note that currently, no target is using dm_bufio_set_sector_offset and
dm_bufio_get_device_size simultaneously, so this patch has no effect.
However, an upcoming patch that fixes dm-verity-fec needs this change.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Reviewed-by: Milan Broz <gmazyland at gmail.com>
Cc: stable at vger.kernel.org
---
 drivers/md/dm-bufio.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index fce4cbf9529d..50f3e673729c 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1526,6 +1526,10 @@ EXPORT_SYMBOL_GPL(dm_bufio_get_block_size);
 sector_t dm_bufio_get_device_size(struct dm_bufio_client *c)
 {
 	sector_t s = i_size_read(c->bdev->bd_inode) >> SECTOR_SHIFT;
+	if (s >= c->start)
+		s -= c->start;
+	else
+		s = 0;
 	if (likely(c->sectors_per_block_bits >= 0))
 		s >>= c->sectors_per_block_bits;
 	else
-- 
2.30.1