[PATCH v2 0/5] partitions: add AIX LVM support

[PATCH v2 0/5] partitions: add AIX LVM support

[Philippe De Muyter]

This is a revision of the patch serie I sent some days ago, with fixes
based on observations by Karel Zak, and other cleanups.

This enables finding the contiguous partitions in AIX LVM disks.

Patch 1 is actually just a cleanup of msdos.c, but as patch 3 depends
on it I prefer to put it here.

Philippe

[PATCH 1/5] partitions/msdos.c: end-of-line whitespace and semicolon cleanup
[PATCH 2/5] Add aix lvm partitions support files
[PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions
[PATCH 4/5] partitions/Makefile: compile aix.c if configured.
[PATCH 5/5] partitions/Kconfig: add the AIX_PARTITION entry

[PATCH 1/5] partitions/msdos.c: end-of-line whitespace and semicolon cleanup

[Philippe De Muyter]

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 block/partitions/msdos.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/partitions/msdos.c b/block/partitions/msdos.c
index 7681cd2..9bf19e6 100644
--- a/block/partitions/msdos.c
+++ b/block/partitions/msdos.c
@@ -90,7 +90,7 @@ static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
 		if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M')
 			ret = 1;
 		put_dev_sector(sect);
-	};
+	}
 	return ret;
 }
 
@@ -142,7 +142,7 @@ static void parse_extended(struct parsed_partitions *state,
 			return;
 
 		if (!msdos_magic_present(data + 510))
-			goto done; 
+			goto done;
 
 		p = (struct partition *) (data + 0x1be);
 
@@ -155,7 +155,7 @@ static void parse_extended(struct parsed_partitions *state,
 		 * and OS/2 seems to use all four entries.
 		 */
 
-		/* 
+		/*
 		 * First process the data partition(s)
 		 */
 		for (i=0; i<4; i++, p++) {
@@ -263,7 +263,7 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 }
 
 #if defined(CONFIG_BSD_DISKLABEL)
-/* 
+/*
  * Create devices for BSD partitions listed in a disklabel, under a
  * dos-like partition. See parse_extended() for more information.
  */
@@ -294,7 +294,7 @@ static void parse_bsd(struct parsed_partitions *state,
 
 		if (state->next == state->limit)
 			break;
-		if (p->p_fstype == BSD_FS_UNUSED) 
+		if (p->p_fstype == BSD_FS_UNUSED)
 			continue;
 		bsd_start = le32_to_cpu(p->p_offset);
 		bsd_size = le32_to_cpu(p->p_size);
@@ -441,7 +441,7 @@ static struct {
 	{NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
 	{0, NULL},
 };
- 
+
 int msdos_partition(struct parsed_partitions *state)
 {
 	sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
-- 
1.7.1

[PATCH 2/5] Add aix lvm partitions support files

[Philippe De Muyter]

adding partitions/aix.h and partitions/aix.c

Partitions (called Logical Volumes in AIX) can be non-contiguous or
even split on more than one disk.  Altough we detect such partitions,
we cannot describe them to the Linux partitions layer, so we simply
discard them and issue a diagnose message.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 block/partitions/aix.c |  290 ++++++++++++++++++++++++++++++++++++++++++++++++
 block/partitions/aix.h |    1 +
 2 files changed, 291 insertions(+), 0 deletions(-)
 create mode 100644 block/partitions/aix.c
 create mode 100644 block/partitions/aix.h

diff --git a/block/partitions/aix.c b/block/partitions/aix.c
new file mode 100644
index 0000000..b3288d2
--- /dev/null
+++ b/block/partitions/aix.c
@@ -0,0 +1,290 @@
+/*
+ *  fs/partitions/aix.c
+ *
+ *  Copyright (C) 2012-2013 Philippe De Muyter <phdm@macqel.be>
+ */
+
+#include "check.h"
+#include "aix.h"
+
+struct lvm_rec {
+	char lvm_id[4]; /* "_LVM" */
+	char reserved4[16];
+	__be32 lvmarea_len;
+	__be32 vgda_len;
+	__be32 vgda_psn[2];
+	char reserved36[10];
+	__be16 pp_size; /* log2(pp_size) */
+	char reserved46[12];
+	__be16 version;
+	};
+
+struct vgda {
+	__be32 secs;
+	__be32 usec;
+	char reserved8[16];
+	__be16 numlvs;
+	__be16 maxlvs;
+	__be16 pp_size;
+	__be16 numpvs;
+	__be16 total_vgdas;
+	__be16 vgda_size;
+	};
+
+struct lvd {
+	__be16 lv_ix;
+	__be16 res2;
+	__be16 res4;
+	__be16 maxsize;
+	__be16 lv_state;
+	__be16 mirror;
+	__be16 mirror_policy;
+	__be16 num_lps;
+	__be16 res10[8];
+	};
+
+struct lvname {
+	char name[64];
+	};
+
+struct ppe {
+	__be16 lv_ix;
+	unsigned short res2;
+	unsigned short res4;
+	__be16 lp_ix;
+	unsigned short res8[12];
+	};
+
+struct pvd {
+	char reserved0[16];
+	__be16 pp_count;
+	char reserved18[2];
+	__be32 psn_part1;
+	char reserved24[8];
+	struct ppe ppe[1016];
+	};
+
+#define LVM_MAXLVS 256
+
+/**
+ * last_lba(): return number of last logical block of device
+ * @bdev: block device
+ *
+ * Description: Returns last LBA value on success, 0 on error.
+ * This is stored (by sd and ide-geometry) in
+ *  the part[0] entry for this disk, and is the number of
+ *  physical sectors available on the disk.
+ */
+static u64 last_lba(struct block_device *bdev)
+{
+	if (!bdev || !bdev->bd_inode)
+		return 0;
+	return (bdev->bd_inode->i_size >> 9) - 1ULL;
+}
+
+/**
+ * read_lba(): Read bytes from disk, starting at given LBA
+ * @state
+ * @lba
+ * @buffer
+ * @count
+ *
+ * Description:  Reads @count bytes from @state->bdev into @buffer.
+ * Returns number of bytes read on success, 0 on error.
+ */
+static size_t read_lba(struct parsed_partitions *state, u64 lba, u8 * buffer, size_t count)
+{
+	size_t totalreadcount = 0;
+
+	if (!buffer || lba + count / 512 > last_lba(state->bdev))
+                return 0;
+
+	while (count) {
+		int copied = 512;
+		Sector sect;
+		unsigned char *data = read_part_sector(state, lba++, &sect);
+		if (!data)
+			break;
+		if (copied > count)
+			copied = count;
+		memcpy(buffer, data, copied);
+		put_dev_sector(sect);
+		buffer += copied;
+		totalreadcount +=copied;
+		count -= copied;
+	}
+	return totalreadcount;
+}
+
+/**
+ * alloc_pvd(): reads physical volume descriptor
+ * @state
+ * @lba
+ *
+ * Description: Returns pvd on success,  NULL on error.
+ * Allocates space for pvd and fill it with disk blocks at @lba
+ * Notes: remember to free pvd when you're done!
+ */
+static struct pvd *alloc_pvd(struct parsed_partitions *state, u32 lba)
+{
+	size_t count = sizeof(struct pvd);
+	struct pvd *p;
+
+	p = kmalloc(count, GFP_KERNEL);
+	if (!p)
+		return NULL;
+
+	if (read_lba(state, lba, (u8 *) p, count) < count) {
+		kfree(p);
+		return NULL;
+	}
+	return p;
+}
+
+/**
+ * alloc_lvn(): reads logical volume names
+ * @state
+ * @lba
+ *
+ * Description: Returns lvn on success,  NULL on error.
+ * Allocates space for lvn and fill it with disk blocks at @lba
+ * Notes: remember to free lvn when you're done!
+ */
+static struct lvname *alloc_lvn(struct parsed_partitions *state, u32 lba)
+{
+	size_t count = sizeof(struct lvname) * LVM_MAXLVS;
+	struct lvname *p;
+
+	p = kmalloc(count, GFP_KERNEL);
+	if (!p)
+		return NULL;
+
+	if (read_lba(state, lba, (u8 *) p, count) < count) {
+		kfree(p);
+		return NULL;
+	}
+	return p;
+}
+
+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;
+	struct lv_info {
+		unsigned short pps_per_lv;
+		unsigned short pps_found;
+		unsigned char lv_is_contiguous;
+	} *lvip;
+	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);
+			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);
+	}
+	lvip = kzalloc(sizeof(struct lv_info) * state->limit, GFP_KERNEL);
+	if (!lvip)
+		return 0;
+	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 foundlvs = 0;
+
+			for (i = 0; foundlvs < numlvs && i < state->limit; i += 1) {
+				lvip[i].pps_per_lv = be16_to_cpu(p[i].num_lps);
+				if (lvip[i].pps_per_lv)
+					foundlvs += 1;
+			}
+		}
+		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;
+			unsigned 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;
+			if (lv_ix > state->limit) {
+				cur_lv_ix = -1;
+				continue;
+			}
+			lvip[lv_ix].pps_found += 1;
+			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 == lvip[lv_ix].pps_per_lv) {
+				char tmp[70];
+
+				put_partition(state, lv_ix + 1,
+					(i + 1 - lp_ix) * pp_blocks_size + psn_part1,
+					lvip[lv_ix].pps_per_lv * pp_blocks_size);
+				snprintf(tmp, sizeof(tmp), " <%s>\n", n[lv_ix].name);
+				strlcat(state->pp_buf, tmp, PAGE_SIZE);
+				lvip[lv_ix].lv_is_contiguous = 1;
+				ret = 1;
+				next_lp_ix = 1;
+			} else
+				next_lp_ix += 1;
+		}
+		for (i = 0; i < state->limit; i += 1)
+			if (lvip[i].pps_found && !lvip[i].lv_is_contiguous)
+				printk("partition %s (%u pp's found) is not contiguous\n",
+					n[i].name, lvip[i].pps_found);
+		kfree(pvd);
+	}
+	if (n)
+		kfree(n);
+	kfree(lvip);
+	return ret;
+}
diff --git a/block/partitions/aix.h b/block/partitions/aix.h
new file mode 100644
index 0000000..e0c66a9
--- /dev/null
+++ b/block/partitions/aix.h
@@ -0,0 +1 @@
+extern int aix_partition(struct parsed_partitions *state);
-- 
1.7.1

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

[Andrew Morton]

On Mon, 29 Apr 2013 23:18:30 +0200 Philippe De Muyter <phdm@macqel.be> wrote:

> adding partitions/aix.h and partitions/aix.c
> 
> Partitions (called Logical Volumes in AIX) can be non-contiguous or
> even split on more than one disk.  Altough we detect such partitions,
> we cannot describe them to the Linux partitions layer, so we simply
> discard them and issue a diagnose message.

This description is rather hard to follow.

It appears that the new code permits Linux to access some types of AIX
partitions, but not other types, correct?  If so, can we please provide
a more explicit description of which typesw are and are not supported?

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

[Philippe De Muyter]

Hi Andrew,

On Mon, May 20, 2013 at 04:39:27PM -0700, Andrew Morton wrote:
> On Mon, 29 Apr 2013 23:18:30 +0200 Philippe De Muyter <phdm@macqel.be> wrote:
> 
> > adding partitions/aix.h and partitions/aix.c
> > 
> > Partitions (called Logical Volumes in AIX) can be non-contiguous or
> > even split on more than one disk.  Altough we detect such partitions,
> > we cannot describe them to the Linux partitions layer, so we simply
> > discard them and issue a diagnose message.
> 
> This description is rather hard to follow.
> 
> It appears that the new code permits Linux to access some types of AIX
> partitions, but not other types, correct?  If so, can we please provide
> a more explicit description of which typesw are and are not supported?
> 

AIX LVM permits to make "logical volumes" which are made of multiple slices
of multiple disks.  The new code allows only access to the "logical volumes"
which are made of one slice on the probed disk, a slice being a contiguous
disk area.  The code also detects "logical volumes" made of multiple slices
on the probed disk, but can not describe them to the partition layer, because
the partition layer generic code does not support that.  When such
non-contiguous "logical volumes" are detected, a diagnostic message is
printed.

Philippe

-- 
Philippe De Muyter +32 2 6101532 Macq SA rue de l'Aeronef 2 B-1140 Bruxelles

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

[Christoph Hellwig]

On Tue, May 21, 2013 at 09:27:54AM +0200, Philippe De Muyter wrote:
> AIX LVM permits to make "logical volumes" which are made of multiple slices
> of multiple disks.  The new code allows only access to the "logical volumes"
> which are made of one slice on the probed disk, a slice being a contiguous
> disk area.  The code also detects "logical volumes" made of multiple slices
> on the probed disk, but can not describe them to the partition layer, because
> the partition layer generic code does not support that.  When such
> non-contiguous "logical volumes" are detected, a diagnostic message is
> printed.

This very much screams like it should be implemented in the lvm2
userspace package using the dm kernel driver.

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

[Philippe De Muyter]

On Fri, May 24, 2013 at 06:04:52AM -0400, Christoph Hellwig wrote:
> On Tue, May 21, 2013 at 09:27:54AM +0200, Philippe De Muyter wrote:
> > AIX LVM permits to make "logical volumes" which are made of multiple slices
> > of multiple disks.  The new code allows only access to the "logical volumes"
> > which are made of one slice on the probed disk, a slice being a contiguous
> > disk area.  The code also detects "logical volumes" made of multiple slices
> > on the probed disk, but can not describe them to the partition layer, because
> > the partition layer generic code does not support that.  When such
> > non-contiguous "logical volumes" are detected, a diagnostic message is
> > printed.
> 
> This very much screams like it should be implemented in the lvm2
> userspace package using the dm kernel driver.

Is lvm2 a generic tool for discovering foreign partition layouts, or it is
about one linux-specific lvm implementation ?

Philippe

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

[Christoph Hellwig]

On Fri, May 24, 2013 at 12:58:52PM +0200, Philippe De Muyter wrote:
> > This very much screams like it should be implemented in the lvm2
> > userspace package using the dm kernel driver.
> 
> Is lvm2 a generic tool for discovering foreign partition layouts, or it is
> about one linux-specific lvm implementation ?

lvm is mostly about the Linux specific formats.  If you want to create
a separate userspace consumer for device mapper that's probably also
fine, but if you need support for complex layours device mapper is the
way to go, and the partitioning layer isn't getting you anywhere.

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

[Alasdair G Kergon]

On Mon, Aug 12, 2013 at 04:52:34AM -0700, Christoph Hellwig wrote:
> lvm is mostly about the Linux specific formats.  If you want to create
> a separate userspace consumer for device mapper that's probably also
> fine, but if you need support for complex layours device mapper is the
> way to go, and the partitioning layer isn't getting you anywhere.
 
If you can map the AIX volume manager objects onto the linux ones, you
can write a 'format' module for lvm2 to handle them.

Alasdair

[PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions

[Philippe De Muyter]

Graft AIX partitions enumeration in partitions/msdos.c

There is already a AIX disks detection logic in msdos.c.  When an
AIX disk has been found, and if configured to, call the aix partitions
recognizer.  This avoids removal of AIX disks protection from msdos.c,
avoids code duplication, and ensures that AIX partitions enumeration
is called before plain msdos partitions enumeration.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 block/partitions/msdos.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/block/partitions/msdos.c b/block/partitions/msdos.c
index 9bf19e6..9123f25 100644
--- a/block/partitions/msdos.c
+++ b/block/partitions/msdos.c
@@ -23,6 +23,7 @@
 #include "check.h"
 #include "msdos.h"
 #include "efi.h"
+#include "aix.h"
 
 /*
  * Many architectures don't like unaligned accesses, while
@@ -462,8 +463,12 @@ int msdos_partition(struct parsed_partitions *state)
 	 */
 	if (aix_magic_present(state, data)) {
 		put_dev_sector(sect);
+#ifdef CONFIG_AIX_PARTITION
+		return aix_partition(state);
+#else
 		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
 		return 0;
+#endif
 	}
 
 	if (!msdos_magic_present(data + 510)) {
-- 
1.7.1

Re: [PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions

[Andrew Morton]

On Mon, 29 Apr 2013 23:18:31 +0200 Philippe De Muyter <phdm@macqel.be> wrote:

> Graft AIX partitions enumeration in partitions/msdos.c
> 
> There is already a AIX disks detection logic in msdos.c.  When an
> AIX disk has been found, and if configured to, call the aix partitions
> recognizer.  This avoids removal of AIX disks protection from msdos.c,
> avoids code duplication, and ensures that AIX partitions enumeration
> is called before plain msdos partitions enumeration.
> 
> ...
>
> --- a/block/partitions/msdos.c
> +++ b/block/partitions/msdos.c
> @@ -23,6 +23,7 @@
>  #include "check.h"
>  #include "msdos.h"
>  #include "efi.h"
> +#include "aix.h"
>  
>  /*
>   * Many architectures don't like unaligned accesses, while
> @@ -462,8 +463,12 @@ int msdos_partition(struct parsed_partitions *state)
>  	 */
>  	if (aix_magic_present(state, data)) {
>  		put_dev_sector(sect);
> +#ifdef CONFIG_AIX_PARTITION
> +		return aix_partition(state);
> +#else
>  		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
>  		return 0;
> +#endif
>  	}
>  
>  	if (!msdos_magic_present(data + 510)) {

hm, what's going on here.

Why does partitions/msdos.c know about AIX at all?  Is there something
special about AIX partitioning which ties it in with msdos?

Now that we have AIX partitioning support, can we simply remove the AIX
code from msdos.c?  So msdos.c will say "I don't know what that is",
and we fall through to aix.c which says "that's mine!"?

Re: [PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions

[Philippe De Muyter]

Hi Andrew,

On Mon, May 20, 2013 at 04:41:52PM -0700, Andrew Morton wrote:
> On Mon, 29 Apr 2013 23:18:31 +0200 Philippe De Muyter <phdm@macqel.be> wrote:
> 
> > Graft AIX partitions enumeration in partitions/msdos.c
> > 
> > There is already a AIX disks detection logic in msdos.c.  When an
> > AIX disk has been found, and if configured to, call the aix partitions
> > recognizer.  This avoids removal of AIX disks protection from msdos.c,
> > avoids code duplication, and ensures that AIX partitions enumeration
> > is called before plain msdos partitions enumeration.
> > 
> > ...
> >
> > --- a/block/partitions/msdos.c
> > +++ b/block/partitions/msdos.c
> > @@ -23,6 +23,7 @@
> >  #include "check.h"
> >  #include "msdos.h"
> >  #include "efi.h"
> > +#include "aix.h"
> >  
> >  /*
> >   * Many architectures don't like unaligned accesses, while
> > @@ -462,8 +463,12 @@ int msdos_partition(struct parsed_partitions *state)
> >  	 */
> >  	if (aix_magic_present(state, data)) {
> >  		put_dev_sector(sect);
> > +#ifdef CONFIG_AIX_PARTITION
> > +		return aix_partition(state);
> > +#else
> >  		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
> >  		return 0;
> > +#endif
> >  	}
> >  
> >  	if (!msdos_magic_present(data + 510)) {
> 
> hm, what's going on here.
> 
> Why does partitions/msdos.c know about AIX at all?  Is there something
> special about AIX partitioning which ties it in with msdos?

Well, PowerPC BIOS (PPCBUG or Open Firmware) mimics PC BIOS and requires the
first block of the disk to describe the boot partition the same way that
PC BIOS does.  Remember, the aim of IBM, Motorola and Apple was to replace
the PC's by PowerPC's :).  So, an AIX disk can erroneously be recognized as
a dos disk with two partitions (two times the same boot partition).  That's
the reason why there is already code in block/partitions/msdos.c to avoid
that.
> 
> Now that we have AIX partitioning support, can we simply remove the AIX
> code from msdos.c?  So msdos.c will say "I don't know what that is",
> and we fall through to aix.c which says "that's mine!"?

I didn't want to remove the AIX protection from msdos.c, for the likely case
that someone would compile the kernel without AIX_PARTITION support,  And, as
a part of the AIX detection was already done by 'aix_magic_present', I did
not want to duplicate it.  I can move the AIX detection logic to aix.c and
still keep the AIX protection for msdos.c with some more #ifdef's if you prefer.

Philippe

[PATCH 4/5] partitions/Makefile: compile aix.c if configured.

[Philippe De Muyter]

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 block/partitions/Makefile |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/block/partitions/Makefile b/block/partitions/Makefile
index 03af8ea..2be4d7b 100644
--- a/block/partitions/Makefile
+++ b/block/partitions/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_BLOCK) := check.o
 obj-$(CONFIG_ACORN_PARTITION) += acorn.o
 obj-$(CONFIG_AMIGA_PARTITION) += amiga.o
 obj-$(CONFIG_ATARI_PARTITION) += atari.o
+obj-$(CONFIG_AIX_PARTITION) += aix.o
 obj-$(CONFIG_MAC_PARTITION) += mac.o
 obj-$(CONFIG_LDM_PARTITION) += ldm.o
 obj-$(CONFIG_MSDOS_PARTITION) += msdos.o
-- 
1.7.1

[PATCH 5/5] partitions/Kconfig: add the AIX_PARTITION entry

[Philippe De Muyter]

This is the final patch enabling a user to select AIX lvm partitions
detection.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 block/partitions/Kconfig |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/block/partitions/Kconfig b/block/partitions/Kconfig
index 75a54e1..4cebb2f 100644
--- a/block/partitions/Kconfig
+++ b/block/partitions/Kconfig
@@ -68,6 +68,17 @@ config ACORN_PARTITION_RISCIX
 	  of machines called RISCiX.  If you say 'Y' here, Linux will be able
 	  to read disks partitioned under RISCiX.
 
+config AIX_PARTITION
+	bool "AIX basic partition table support" if PARTITION_ADVANCED
+	help
+	  Say Y here if you would like to be able to read the hard disk
+	  partition table format used by IBM or Motorola PowerPC machines
+	  running AIX.  AIX actually uses a Logical Volume Manager, where
+	  "logical volumes" can be spread across one or multiple disks,
+	  but this driver works only for the simple case of partitions which
+	  are contiguous.
+	  Otherwise, say N.
+
 config OSF_PARTITION
 	bool "Alpha OSF partition support" if PARTITION_ADVANCED
 	default y if ALPHA
-- 
1.7.1

[PATCH v3 0/5] partitions: Add aix lvm partitions support

[Philippe De Muyter]

This is the version 3 of my patchset to add a basic aix lvm partitions
parser to linux.
The only modified patch is patch 2.  It fixes a problem in the discovering
of small (1 pp) partitions in presence of discontiguous partitions.

Jens, patch 1 is actually just a cleanup of msdos.c.  You could apply it
already even if you delay the decision for the other ones, so I could
stop resending it here, as patch 3 depends on it.

Philippe

[PATCH 1/5] partitions/msdos.c: end-of-line whitespace and semicolon cleanup
[PATCH 2/5] partitions: Add aix lvm partitions support files
[PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions
[PATCH 4/5] partitions/Makefile: compile aix.c if configured.
[PATCH 5/5] partitions/Kconfig: add the AIX_PARTITION entry

[PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions

[Philippe De Muyter]

From: Philippe De Muyter <phdm@macqel.be>

Graft AIX partitions enumeration in partitions/msdos.c

There is already a AIX disks detection logic in msdos.c.  When an
AIX disk has been found, and if configured to, call the aix partitions
recognizer.  This avoids removal of AIX disks protection from msdos.c,
avoids code duplication, and ensures that AIX partitions enumeration
is called before plain msdos partitions enumeration.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Karel Zak <kzak@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 block/partitions/msdos.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/block/partitions/msdos.c b/block/partitions/msdos.c
index 9bf19e6..9123f25 100644
--- a/block/partitions/msdos.c
+++ b/block/partitions/msdos.c
@@ -23,6 +23,7 @@
 #include "check.h"
 #include "msdos.h"
 #include "efi.h"
+#include "aix.h"
 
 /*
  * Many architectures don't like unaligned accesses, while
@@ -462,8 +463,12 @@ int msdos_partition(struct parsed_partitions *state)
 	 */
 	if (aix_magic_present(state, data)) {
 		put_dev_sector(sect);
+#ifdef CONFIG_AIX_PARTITION
+		return aix_partition(state);
+#else
 		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
 		return 0;
+#endif
 	}
 
 	if (!msdos_magic_present(data + 510)) {
-- 
1.7.1

[RFC PATCH 0/5] Add aix lvm partitions support

[Philippe De Muyter]

This patches serie implements a mapping from AIX LVM logical volumes
to linux partitions, for AIX disks from versions AIX 3 & AIX 4,
maybe later versions also, but this has not been tested.

Because the LVM layer of AIX allows logical volumes to be made of
separate so-called physical partitions which can be anywhere on the
disk, and allows up to 256 logical volumes, while Linux allows
only 16 partitions per disk, partitions which must be contiguous,
only a subset of the AIX logical volumes found can be mappedi to linux
partitions, but that's enough to make it usefull in real life.

AIX partitions discovery has been grafted to the msdos partitions
code, because AIX disks often contain an msdos partition table,
and this grafting avoids removal of the AIX protection already
included in msdos.c while avoiding code duplication.

Comments welcome

Philippe

PS: a companion AIX JFS fs read-only driver will follow

[PATCH 1/5] partitions/msdos.c: end-of-line whitespace and semicolon cleanup
[PATCH 2/5] Add aix lvm partitions support files
[PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions
[PATCH 4/5] partitions/Makefile: compile aix.c if configured.
[PATCH 5/5] partitions/Kconfig: add the AIX_PARTITION entry

[PATCH 3/5] partitions/msdos: enumerate also AIX LVM partitions

[Philippe De Muyter]

Graft AIX partitions enumeration in partitions/msdos.c

There is already a AIX disks detection logic in msdos.c.  When an
AIX disk has been found, and if configured to, call the aix partitions
recognizer.  This avoids removal of AIX disks protection from msdos.c,
avoids code duplication, and ensures that AIX partitions enumeration
is called before plain msdos partitions enumeration.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Jens Axboe <axboe@kernel.dk>
---
 block/partitions/msdos.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/block/partitions/msdos.c b/block/partitions/msdos.c
index 9bf19e6..9123f25 100644
--- a/block/partitions/msdos.c
+++ b/block/partitions/msdos.c
@@ -23,6 +23,7 @@
 #include "check.h"
 #include "msdos.h"
 #include "efi.h"
+#include "aix.h"
 
 /*
  * Many architectures don't like unaligned accesses, while
@@ -462,8 +463,12 @@ int msdos_partition(struct parsed_partitions *state)
 	 */
 	if (aix_magic_present(state, data)) {
 		put_dev_sector(sect);
+#ifdef CONFIG_AIX_PARTITION
+		return aix_partition(state);
+#else
 		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
 		return 0;
+#endif
 	}
 
 	if (!msdos_magic_present(data + 510)) {
-- 
1.7.1