Commit dd545b52 authored Jan 10, 2017 by Chandan Rajendra Committed by Jens Axboe Jan 10, 2017

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>

parent a121103c

fs/direct-io.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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)

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