On Mon, 26 Feb 2018 11:54:30 +0200 Nikolay Borisov <nborisov@xxxxxxxx> wrote:
> We already get the block counts and the calculate the end block at the
> beginning of the function. Let's use the local variables for consistency and
> readability. No functional changes
>
Fair enough.
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -1200,7 +1200,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
> }
>
> /* watch out for a 0 len io from a tricksy fs */
> - if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
> + if (iov_iter_rw(iter) == READ && !count)
> return 0;
>
> dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
> @@ -1316,8 +1316,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>
> dio->should_dirty = (iter->type == ITER_IOVEC);
> sdio.iter = iter;
> - sdio.final_block_in_request =
> - (offset + iov_iter_count(iter)) >> blkbits;
> + sdio.final_block_in_request = end >> blkbits;
>
> /*
> * In case of non-aligned buffers, we may need 2 more
It's always scary to see a local being used in this fashion so far away
from where it was initialized. However, we can get our warm fuzzy
feelings by doing this:
--- a/fs/direct-io.c~direct-io-minor-cleanups-in-do_blockdev_direct_io-fix
+++ a/fs/direct-io.c
@@ -1178,9 +1178,9 @@ do_blockdev_direct_IO(struct kiocb *iocb
unsigned blkbits = i_blkbits;
unsigned blocksize_mask = (1 << blkbits) - 1;
ssize_t retval = -EINVAL;
- size_t count = iov_iter_count(iter);
+ const size_t count = iov_iter_count(iter);
loff_t offset = iocb->ki_pos;
- loff_t end = offset + count;
+ const loff_t end = offset + count;
struct dio *dio;
struct dio_submit sdio = { 0, };
struct buffer_head map_bh = { 0, };
_
