do_direct_IO: Use inode->i_blkbits to compute block count to be cleaned

The code currently uses sdio->blkbits to compute the number of blocks to
be cleaned. However sdio->blkbits is derived from the logical block size
of the underlying block device (Refer to the definition of
do_blockdev_direct_IO()). Due to this, generic/299 test would rarely
fail when executed on an ext4 filesystem with 64k as the block size and
when using a virtio based disk (having 512 byte as the logical block
size) inside a kvm guest.

This commit fixes the bug by using inode->i_blkbits to compute the
number of blocks to be cleaned.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fixed up by Jeff Moyer to only use/evaluate inode->i_blkbits once,
to avoid issues with block size changes with IO in flight.

Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/fs/direct-io.c b/fs/direct-io.c
index aeae8c06345155e35e6f9d1567d004c6d073ea66..c87bae4376b848f4204c06016eeb223f675dc7db 100644 (file)
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -906,6 +906,7 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
                        struct buffer_head *map_bh)
 {
        const unsigned blkbits = sdio->blkbits;
+       const unsigned i_blkbits = blkbits + sdio->blkfactor;
        int ret = 0;
 
        while (sdio->block_in_file < sdio->final_block_in_request) {
@@ -949,7 +950,7 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
                                        clean_bdev_aliases(
                                                map_bh->b_bdev,
                                                map_bh->b_blocknr,
-                                               map_bh->b_size >> blkbits);
+                                               map_bh->b_size >> i_blkbits);
                                }
 
                                if (!sdio->blkfactor)