Commit e5465795 authored May 24, 2017 by Eric Biggers Committed by Theodore Ts'o May 24, 2017

ext4: fix off-by-one error when writing back pages before dio read



The 'lend' argument of filemap_write_and_wait_range() is inclusive, so
we need to subtract 1 from pos + count.

Note that 'count' is guaranteed to be nonzero since
ext4_file_read_iter() returns early when given a 0 count.

Fixes: 16c54688 ("ext4: Allow parallel DIO reads")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

parent 624327f8

fs/ext4/inode.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -3713,7 +3713,7 @@ static ssize_t ext4_direct_IO_read(struct kiocb iocb, struct iov_iter iter)
		*/
		inode_lock_shared(inode);
		ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
		iocb->ki_pos + count);
		iocb->ki_pos + count - 1);
		if (ret)
		goto out_unlock;
		ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,

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