Commit c663e29f authored Oct 24, 2016 by Jan Kara Committed by Dave Chinner Oct 24, 2016

fs: Do to trim high file position bits in iomap_page_mkwrite_actor



iomap_page_mkwrite_actor() calls __block_write_begin_int() with position
masked as pos & ~PAGE_MASK which is equivalent to pos & (PAGE_SIZE-1).
Thus it masks off high bits of file position. However
__block_write_begin_int() expects full file position on input. This does
not cause any visible issues because all __block_write_begin_int()
really cares about are low file position bits but still it is a bug
waiting to happen.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

parent 64e6428d

fs/iomap.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -433,8 +433,7 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
		struct page *page = data;
		int ret;

		ret = __block_write_begin_int(page, pos & ~PAGE_MASK, length,
		NULL, iomap);
		ret = __block_write_begin_int(page, pos, length, NULL, iomap);
		if (ret)
		return ret;

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