linux-kernel - Re: [PATCH 22/31] fs/ntfs: use kmemdup rather than duplicating its implementation

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Message-Id: <449F7556-40CD-4BE6-9E5F-0F5603152998@tuxera.com>
Date:	Wed, 23 Sep 2015 11:21:53 +0100
From:	Anton Altaparmakov <anton@...era.com>
To:	Andrzej Hajda <a.hajda@...sung.com>
Cc:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-kernel@...r.kernel.org, linux-ntfs-dev@...ts.sourceforge.net
Subject: Re: [PATCH 22/31] fs/ntfs: use kmemdup rather than duplicating its implementation

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@...sung.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@...sung.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

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