linux-ext4 - Re: [PATCH] create_inode: fix copying large files

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Date:   Fri, 1 Feb 2019 09:47:15 -0800
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Ross Burton <ross.burton@...el.com>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: [PATCH] create_inode: fix copying large files

On Fri, Feb 01, 2019 at 12:51:59PM +0000, Ross Burton wrote:
> When copying large files into a ext filesystem at mkfs time the copy fails at
> 2^31 bytes in.  There are two problems:
> 
> copy_file_chunk() passes an offset (off_t, 64-bit typically) to
> ext2fs_file_lseek() which expects a ext2_off_t (typedef to __u32) so the value
> is truncated. Solve by calling ext2fs_file_llseek() which takes a u64 offset
> instead.
> 
> try_lseek_copy() rounds the data and hole offsets as found by lseek() to block
> boundaries, but the calculation gets truncated to 32-bits.  Solve by casting the
> 32-bit blocksize to off_t to ensure this doesn't happen.
> 
> Signed-off-by: Ross Burton <ross.burton@...el.com>
> ---
>  misc/create_inode.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/misc/create_inode.c b/misc/create_inode.c
> index 05aa6363..f106dcda 100644
> --- a/misc/create_inode.c
> +++ b/misc/create_inode.c
> @@ -438,7 +438,7 @@ static errcode_t copy_file_chunk(ext2_filsys fs, int fd, ext2_file_t e2_file,
>  				ptr += blen;
>  				continue;
>  			}
> -			err = ext2fs_file_lseek(e2_file, off + bpos,
> +			err = ext2fs_file_llseek(e2_file, off + bpos,
>  						EXT2_SEEK_SET, NULL);
>  			if (err)
>  				goto fail;
> @@ -481,7 +481,7 @@ static errcode_t try_lseek_copy(ext2_filsys fs, int fd, struct stat *statbuf,
>  			return EXT2_ET_UNIMPLEMENTED;
>  
>  		data_blk = data & ~(fs->blocksize - 1);

Do we need to cast this one too?  ^^^^^^^

(Looks reasonable otherwise...)

--D

> -		hole_blk = (hole + (fs->blocksize - 1)) & ~(fs->blocksize - 1);
> +		hole_blk = (hole + (off_t)(fs->blocksize - 1)) & ~(off_t)(fs->blocksize - 1);
>  		err = copy_file_chunk(fs, fd, e2_file, data_blk, hole_blk, buf,
>  				      zerobuf);
>  		if (err)
> -- 
> 2.11.0
>