dm: use i_size_read

Use i_size_read() instead of reading i_size.

If someone changes the size of the device simultaneously, i_size_read
is guaranteed to return a valid value (either the old one or the new one).

i_size can return some intermediate invalid value (on 32-bit computers
with 64-bit i_size, the reads to both halves of i_size can be interleaved
with updates to i_size, resulting in garbage being returned).

Cc: stable@kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 6fa8ccf91c70..6352a9ad4446 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -416,7 +416,7 @@ static int create_log_context(struct dm_dirty_log *log, struct dm_target *ti,
                                        bitset_size,
                                        ti->limits.logical_block_size);
 
-                if (buf_size > dev->bdev->bd_inode->i_size) {
+                if (buf_size > i_size_read(dev->bdev->bd_inode)) {
                         DMWARN("log device %s too small: need %llu bytes",
                                 dev->name, (unsigned long long)buf_size);
                         kfree(lc);