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Message-ID: <20131125080101.GB5964@gmail.com>
Date:	Mon, 25 Nov 2013 16:01:01 +0800
From:	Zheng Liu <gnehzuil.liu@...il.com>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
Cc:	tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 07/25] mke2fs: load configfile blocksize setting before
 64bit checks

On Thu, Oct 17, 2013 at 09:49:42PM -0700, Darrick J. Wong wrote:
> mke2fs has a series of checks to ensure that we don't create a
> filesystem too big for its blocksize -- if auto-64bit is on, then it
> turns on 64bit; otherwise it complains.  Unfortunately, it performs
> these checks before looking in mke2fs.conf for a blocksize, which
> means that the checks are incorrect if the user specifies a non-4096
> blocksize in the config file and says nothing on the command line.  It
> also has the effect of mandating a 4k block size on any block device
> larger than 4T in that situation.  Therefore, read the block size from
> the config file before performing the 64bit checks.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>

Reviewed-by: Zheng Liu <wenqing.lz@...bao.com>

                                                - Zheng

> ---
>  misc/mke2fs.c |  132 ++++++++++++++++++++++++++++++---------------------------
>  1 file changed, 70 insertions(+), 62 deletions(-)
> 
> 
> diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> index ce3c696..86091d7 100644
> --- a/misc/mke2fs.c
> +++ b/misc/mke2fs.c
> @@ -1298,6 +1298,21 @@ static void PRS(int argc, char *argv[])
>  	char *		fs_type = 0;
>  	char *		usage_types = 0;
>  	blk64_t		dev_size;
> +	/*
> +	 * NOTE: A few words about fs_blocks_count and blocksize:
> +	 *
> +	 * Initially, blocksize is set to zero, which implies 1024.
> +	 * If -b is specified, blocksize is updated to the user's value.
> +	 *
> +	 * Next, the device size or the user's "blocks" command line argument
> +	 * is used to set fs_blocks_count; the units are blocksize.
> +	 *
> +	 * Later, if blocksize hasn't been set and the profile specifies a
> +	 * blocksize, then blocksize is updated and fs_blocks_count is scaled
> +	 * appropriately.  Note the change in units!
> +	 *
> +	 * Finally, we complain about fs_blocks_count > 2^32 on a non-64bit fs.
> +	 */
>  	blk64_t		fs_blocks_count = 0;
>  #ifdef __linux__
>  	struct 		utsname ut;
> @@ -1780,15 +1795,65 @@ profile_error:
>  		}
>  	}
>  
> +	/* Get the hardware sector sizes, if available */
> +	retval = ext2fs_get_device_sectsize(device_name, &lsector_size);
> +	if (retval) {
> +		com_err(program_name, retval,
> +			_("while trying to determine hardware sector size"));
> +		exit(1);
> +	}
> +	retval = ext2fs_get_device_phys_sectsize(device_name, &psector_size);
> +	if (retval) {
> +		com_err(program_name, retval,
> +			_("while trying to determine physical sector size"));
> +		exit(1);
> +	}
> +
> +	if ((tmp = getenv("MKE2FS_DEVICE_SECTSIZE")) != NULL)
> +		lsector_size = atoi(tmp);
> +	if ((tmp = getenv("MKE2FS_DEVICE_PHYS_SECTSIZE")) != NULL)
> +		psector_size = atoi(tmp);
> +
> +	/* Older kernels may not have physical/logical distinction */
> +	if (!psector_size)
> +		psector_size = lsector_size;
> +
> +	if (blocksize <= 0) {
> +		use_bsize = get_int_from_profile(fs_types, "blocksize", 4096);
> +
> +		if (use_bsize == -1) {
> +			use_bsize = sys_page_size;
> +			if ((linux_version_code < (2*65536 + 6*256)) &&
> +			    (use_bsize > 4096))
> +				use_bsize = 4096;
> +		}
> +		if (lsector_size && use_bsize < lsector_size)
> +			use_bsize = lsector_size;
> +		if ((blocksize < 0) && (use_bsize < (-blocksize)))
> +			use_bsize = -blocksize;
> +		blocksize = use_bsize;
> +		fs_blocks_count /= (blocksize / 1024);
> +	} else {
> +		if (blocksize < lsector_size) {			/* Impossible */
> +			com_err(program_name, EINVAL,
> +				_("while setting blocksize; too small "
> +				  "for device\n"));
> +			exit(1);
> +		} else if ((blocksize < psector_size) &&
> +			   (psector_size <= sys_page_size)) {	/* Suboptimal */
> +			fprintf(stderr, _("Warning: specified blocksize %d is "
> +				"less than device physical sectorsize %d\n"),
> +				blocksize, psector_size);
> +		}
> +	}
> +
> +	fs_param.s_log_block_size =
> +		int_log2(blocksize >> EXT2_MIN_BLOCK_LOG_SIZE);
> +
>  	/*
>  	 * We now need to do a sanity check of fs_blocks_count for
>  	 * 32-bit vs 64-bit block number support.
>  	 */
> -	if ((fs_blocks_count > MAX_32_NUM) && (blocksize == 0)) {
> -		fs_blocks_count /= 4; /* Try using a 4k blocksize */
> -		blocksize = 4096;
> -		fs_param.s_log_block_size = 2;
> -	}
>  	if ((fs_blocks_count > MAX_32_NUM) &&
>  	    !(fs_param.s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT) &&
>  	    get_bool_from_profile(fs_types, "auto_64-bit_support", 0)) {
> @@ -1889,63 +1954,6 @@ profile_error:
>  	if ((fs_param.s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) &&
>  	    ((tmp = getenv("MKE2FS_FIRST_META_BG"))))
>  		fs_param.s_first_meta_bg = atoi(tmp);
> -
> -	/* Get the hardware sector sizes, if available */
> -	retval = ext2fs_get_device_sectsize(device_name, &lsector_size);
> -	if (retval) {
> -		com_err(program_name, retval,
> -			_("while trying to determine hardware sector size"));
> -		exit(1);
> -	}
> -	retval = ext2fs_get_device_phys_sectsize(device_name, &psector_size);
> -	if (retval) {
> -		com_err(program_name, retval,
> -			_("while trying to determine physical sector size"));
> -		exit(1);
> -	}
> -
> -	if ((tmp = getenv("MKE2FS_DEVICE_SECTSIZE")) != NULL)
> -		lsector_size = atoi(tmp);
> -	if ((tmp = getenv("MKE2FS_DEVICE_PHYS_SECTSIZE")) != NULL)
> -		psector_size = atoi(tmp);
> -
> -	/* Older kernels may not have physical/logical distinction */
> -	if (!psector_size)
> -		psector_size = lsector_size;
> -
> -	if (blocksize <= 0) {
> -		use_bsize = get_int_from_profile(fs_types, "blocksize", 4096);
> -
> -		if (use_bsize == -1) {
> -			use_bsize = sys_page_size;
> -			if ((linux_version_code < (2*65536 + 6*256)) &&
> -			    (use_bsize > 4096))
> -				use_bsize = 4096;
> -		}
> -		if (lsector_size && use_bsize < lsector_size)
> -			use_bsize = lsector_size;
> -		if ((blocksize < 0) && (use_bsize < (-blocksize)))
> -			use_bsize = -blocksize;
> -		blocksize = use_bsize;
> -		ext2fs_blocks_count_set(&fs_param,
> -					ext2fs_blocks_count(&fs_param) /
> -					(blocksize / 1024));
> -	} else {
> -		if (blocksize < lsector_size) {			/* Impossible */
> -			com_err(program_name, EINVAL,
> -				_("while setting blocksize; too small "
> -				  "for device\n"));
> -			exit(1);
> -		} else if ((blocksize < psector_size) &&
> -			   (psector_size <= sys_page_size)) {	/* Suboptimal */
> -			fprintf(stderr, _("Warning: specified blocksize %d is "
> -				"less than device physical sectorsize %d\n"),
> -				blocksize, psector_size);
> -		}
> -	}
> -
> -	fs_param.s_log_block_size =
> -		int_log2(blocksize >> EXT2_MIN_BLOCK_LOG_SIZE);
>  	if (fs_param.s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_BIGALLOC) {
>  		if (!cluster_size)
>  			cluster_size = get_int_from_profile(fs_types,
> 
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