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Subject: Re: [PATCH 22/31] fs/ntfs: use kmemdup rather than duplicating its implementation
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From: Anton Altaparmakov <anton@tuxera.com>
In-Reply-To: <1438934377-4922-23-git-send-email-a.hajda@samsung.com>
Date: Wed, 23 Sep 2015 11:21:53 +0100
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        linux-kernel@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net
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To: Andrzej Hajda <a.hajda@samsung.com>
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Hi Andrzej,

Thanks for your patch.  It looks fine though I don't quite see the point of it to be honest.

It actually adds an additional function call (kmemdup() is not inline) just to save 1 line of source code in the driver and I don't think it improves readability or anything so why bother?  What does it gain?

Best regards,

	Anton

> On 7 Aug 2015, at 08:59, Andrzej Hajda <a.hajda@samsung.com> wrote:
> 
> The patch was generated using fixed coccinelle semantic patch
> scripts/coccinelle/api/memdup.cocci [1].
> 
> [1]: http://permalink.gmane.org/gmane.linux.kernel/2014320
> 
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> ---
> fs/ntfs/dir.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ntfs/dir.c b/fs/ntfs/dir.c
> index 9e38daf..2b7fef0 100644
> --- a/fs/ntfs/dir.c
> +++ b/fs/ntfs/dir.c
> @@ -1172,14 +1172,13 @@ static int ntfs_readdir(struct file *file, struct dir_context *actor)
> 	 * map the mft record without deadlocking.
> 	 */
> 	rc = le32_to_cpu(ctx->attr->data.resident.value_length);
> -	ir = kmalloc(rc, GFP_NOFS);
> +	/* Copy the index root value (it has been verified in read_inode). */
> +	ir = kmemdup((u8 *)ctx->attr + le16_to_cpu(ctx->attr->data.resident.value_offset),
> +		     rc, GFP_NOFS);
> 	if (unlikely(!ir)) {
> 		err = -ENOMEM;
> 		goto err_out;
> 	}
> -	/* Copy the index root value (it has been verified in read_inode). */
> -	memcpy(ir, (u8*)ctx->attr +
> -			le16_to_cpu(ctx->attr->data.resident.value_offset), rc);
> 	ntfs_attr_put_search_ctx(ctx);
> 	unmap_mft_record(ndir);
> 	ctx = NULL;
> -- 
> 1.9.1

-- 
Anton Altaparmakov <anton at tuxera.com> (replace at with @)
Lead in File System Development, Tuxera Inc., http://www.tuxera.com/
Linux NTFS maintainer