linux-kernel - Re: [PATCH 2/5] Add aix lvm partitions support files

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Message-ID: <20130429093756.GB12317@x2.net.home>
Date:	Mon, 29 Apr 2013 11:37:56 +0200
From:	Karel Zak <kzak@...hat.com>
To:	Philippe De Muyter <phdm@...qel.be>
Cc:	linux-kernel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH 2/5] Add aix lvm partitions support files

On Thu, Apr 25, 2013 at 11:10:26PM +0200, Philippe De Muyter wrote:
> +int aix_partition(struct parsed_partitions *state)
> +{
> +	int ret = 0;
> +	Sector sect;
> +	unsigned char *d;
> +	u32 pp_bytes_size;
> +	u32 pp_blocks_size = 0;
> +	u32 vgda_sector = 0;
> +	u32 vgda_len = 0;
> +	int numlvs = 0;
> +	struct pvd *pvd;
> +	unsigned short pps_per_lv[16];
> +	unsigned short pps_found[16];
> +	unsigned char lv_is_contiguous[16];
> +	struct lvname *n = NULL;
> +
> +	d = read_part_sector(state, 7, &sect);
> +	if (d) {
> +		struct lvm_rec *p = (struct lvm_rec *)d;
> +		u16 lvm_version = be16_to_cpu(p->version);
> +		char tmp[64];
> +
> +		if (lvm_version == 1) {
> +			int pp_size_log2 = be16_to_cpu(p->pp_size);
> +
> +			pp_bytes_size = 1 << pp_size_log2;
> +			pp_blocks_size = pp_bytes_size / 512;
> +			snprintf(tmp, sizeof(tmp), " AIX LVM header version %u found\n", lvm_version);

'tmp' is nowhere used, maybe you want to use strlcat(state->pp_buf, tmp, PAGE_SIZE); too.

> +			vgda_len = be32_to_cpu(p->vgda_len);
> +			vgda_sector = be32_to_cpu(p->vgda_psn[0]);
> +		} else {
> +			snprintf(tmp, sizeof(tmp), " unsupported AIX LVM version %d found\n",
> +				lvm_version);
> +			strlcat(state->pp_buf, tmp, PAGE_SIZE);
> +		}
> +		put_dev_sector(sect);
> +	}
> +	if (vgda_sector && (d = read_part_sector(state, vgda_sector, &sect))) {
> +		struct vgda *p = (struct vgda *)d;
> +
> +		numlvs = be16_to_cpu(p->numlvs);
> +		put_dev_sector(sect);
> +	}
> +	if (numlvs && (d = read_part_sector(state, vgda_sector + 1, &sect))) {
> +		struct lvd *p = (struct lvd *)d;
> +		int i;
> +
> +		n = alloc_lvn(state, vgda_sector + vgda_len - 33);
> +		if (n) {
> +			int j = 0;
> +
> +			memset(lv_is_contiguous, 0, 16);
> +			for (i = 0; i < 16; i += 1)
> +				pps_found[i] = 0;

why not memset(pps_found, ....)? I also see magical constant 16
everywhere, maybe you can use sizeof() and ARRAY_SIZE().

> +			for (i = 0; j < numlvs && i < 16; i += 1) {
> +				pps_per_lv[i] = be16_to_cpu(p[i].num_lps);
> +				if (pps_per_lv[i])
> +					j += 1;
> +			}

hmm, what's wrong with j++ and i++, "j += 1" seems like old Python :-)

> +			while (i < 16)
> +				pps_per_lv[i++] = 0;
> +		}
> +		put_dev_sector(sect);
> +	}
> +	pvd = alloc_pvd(state, vgda_sector + 17);
> +	if (pvd) {
> +		int numpps = be16_to_cpu(pvd->pp_count);
> +		int psn_part1 = be32_to_cpu(pvd->psn_part1);
> +		int i;
> +		int cur_lv_ix = -1;
> +		int next_lp_ix = 1;
> +		int lp_ix;
> +
> +		for (i = 0; i < numpps; i += 1) {
> +			struct ppe *p = pvd->ppe + i;
> +			int lv_ix;
> +
> +			lp_ix = be16_to_cpu(p->lp_ix);
> +			if (!lp_ix) {
> +				next_lp_ix = 1;
> +				continue;
> +			}
> +			lv_ix = be16_to_cpu(p->lv_ix) - 1;
> +			pps_found[lv_ix] += 1;

 Would be better to be a little paranoid when you read the data from
 disk and check that lv_ix is in range 0..16 ?

> +			if (lp_ix != next_lp_ix)
> +				continue;
> +			if (lp_ix == 1)
> +				cur_lv_ix = lv_ix;
> +			else if (lv_ix != cur_lv_ix)
> +				next_lp_ix = 1;
> +			if (lp_ix == pps_per_lv[lv_ix]) {
> +				char tmp[70];
> +
> +				put_partition(state, lv_ix + 1,
> +					(i + 1 - lp_ix) * pp_blocks_size + psn_part1,
> +					pps_per_lv[lv_ix] * pp_blocks_size);
> +				snprintf(tmp, sizeof(tmp), " <%s>\n", n[lv_ix].name);
> +				strlcat(state->pp_buf, tmp, PAGE_SIZE);
> +				lv_is_contiguous[lv_ix] = 1;
> +				ret = 1;
> +				next_lp_ix = 1;
> +			} else
> +				next_lp_ix += 1;
> +		}
> +		for (i = 0; i < 16; i += 1)
> +			if (pps_found[i] && !lv_is_contiguous[i])
> +				printk("partition %s (%d pp's found) is not contiguous\n", n[i].name, pps_found[i]);
> +		kfree(pvd);
> +	}
> +	if (n)
> +		kfree(n);
> +	return ret;
> +}

Philippe, do you have any disk image with AIX LVM? It would be nice to
have a way how to test the code. I'd like to add support for AIX to
libblkid too.

    Karel

-- 
 Karel Zak  <kzak@...hat.com>
 http://karelzak.blogspot.com
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