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Commit ab73857e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

direct-io: don't read inode->i_blkbits multiple times 



Since directio can work on a raw block device, and the block size of the
device can change under it, we need to do the same thing that
fs/buffer.c now does: read the block size a single time, using
ACCESS_ONCE().

Reading it multiple times can get different results, which will then
confuse the code because it actually encodes the i_blksize in
relationship to the underlying logical blocksize.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1e8b3332

fs/direct-io.c

+5 −3
Original line number Diff line number Diff line
@@ -540,6 +540,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, 
	sector_t fs_endblk;	/* Into file, in filesystem-sized blocks */

	unsigned long fs_count;	/* Number of filesystem-sized blocks */

	int create;

	unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;



	/*

	 * If there was a memory error and we've overwritten all the
@@ -554,7 +555,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, 
		fs_count = fs_endblk - fs_startblk + 1;



		map_bh->b_state = 0;

		map_bh->b_size = fs_count << dio->inode->i_blkbits;

		map_bh->b_size = fs_count << i_blkbits;



		/*

		 * For writes inside i_size on a DIO_SKIP_HOLES filesystem we
@@ -1053,7 +1054,8 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	int seg;

	size_t size;

	unsigned long addr;

	unsigned blkbits = inode->i_blkbits;

	unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);

	unsigned blkbits = i_blkbits;

	unsigned blocksize_mask = (1 << blkbits) - 1;

	ssize_t retval = -EINVAL;

	loff_t end = offset;
@@ -1149,7 +1151,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, 
	dio->inode = inode;

	dio->rw = rw;

	sdio.blkbits = blkbits;

	sdio.blkfactor = inode->i_blkbits - blkbits;

	sdio.blkfactor = i_blkbits - blkbits;

	sdio.block_in_file = offset >> blkbits;



	sdio.get_block = get_block;