Patchwork block: add command line partition parser

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Submitter Andrew Morton
Date Aug. 15, 2013, 12:30 a.m.
Message ID <20130814173012.2c196085.akpm@linux-foundation.org>
Download mbox | patch
Permalink /patch/267220/
State New
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Comments

Andrew Morton - Aug. 15, 2013, 12:30 a.m.
On Wed, 14 Aug 2013 17:11:51 -0700 Brian Norris <computersforpeace@gmail.com> wrote:

> On Wed, Aug 14, 2013 at 3:57 PM, Andrew Morton
> <akpm@linux-foundation.org> wrote:
> > On Tue, 13 Aug 2013 06:02:17 +0000 Caizhiyong <caizhiyong@huawei.com> wrote:
> >
> >> move the command line parser to a separate module, and change it into
> >> library-style code.
> >>
> >> reference: https://lkml.org/lkml/2013/8/6/550
> 
> The most recent patch is an addendum to this linked patch then?

The unifed latest version is appended.

> > Well OK.  But to prove the library's usefulness and to generally clean
> > up the kernel, someone needs to sign up to the task of converting
> > drivers/mtd/cmdlinepart.c to use this code.
> >
> > I've been hopefully cc'ing various MTD people but am not being
> > overwhelmed with waves of enthusiasm ;)
> 
> "I've been" implies that you have done so prior to this email. And
> "people" implies more than one person. I see that you CC'd David
> Woodhouse over a week ago, but he's fairly silent these days on MTD
> things. It's Artem or me who handle most of the day-to-day of MTD. And
> this is the first time I've seen this! (BTW, please include
> linux-mtd@lists.infradead.org for anything involving MTD.)
> 
> This seems reasonable, and I'd be willing to work with this proposal.

Thanks.

> Caizhiyong, can you submit a clear single patch (or series of
> patches), CC'd to linux-mtd at least? Then we can see about supporting
> it in MTD. It doesn't look too difficult, but I need to check that it
> faithfully mimics the capability we currently rely on. There have been
> previous discussions on changing it, but this was rejected in favor of
> allowing more flexibility. Here's part of one such conversation:
> 
> http://lists.infradead.org/pipermail/linux-mtd/2012-August/043599.html
> http://lists.infradead.org/pipermail/linux-mtd/2012-September/043825.html
> http://lists.infradead.org/pipermail/linux-mtd/2012-December/045322.html
> 
> So I would recommend:
> (1) consider carefully the implications of your command-line format
> now, rather than later
> (2) if you want MTD to use it, it needs to support the features we use now
> 
> Some particular cases to consider: overlapping partitions (how do
> block devices handle overlapping partitions?), out-of-order
> specification, zero sized partitions, mixed syntax (some specified
> with an offset, some not), multiple '-' partitions.

This patch is still at the review-and-under-test stage so now is a fine
time to make changes.

> Anyway, if you resend, we can review.

From: Cai Zhiyong <caizhiyong@huawei.com>
Subject: block: support embedded device command line partition

Read block device partition table from command line.  The partition used
for fixed block device (eMMC) embedded device.  It is no MBR, save storage
space.  Bootloader can be easily accessed by absolute address of data on
the block device.  Users can easily change the partition.

This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
About the partition verbose reference
"Documentation/block/cmdline-partition.txt"

[akpm@linux-foundation.org: fix printk text]
Signed-off-by: Cai Zhiyong <caizhiyong@huawei.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: "Wanglin (Albert)" <albert.wanglin@huawei.com>
Cc: Marius Groeger <mag@sysgo.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/block/cmdline-partition.txt |   40 +++
 block/Kconfig                             |    6 
 block/Makefile                            |    1 
 block/cmdline-parser.c                    |  249 ++++++++++++++++++++
 block/partitions/Kconfig                  |    7 
 block/partitions/Makefile                 |    1 
 block/partitions/check.c                  |    4 
 block/partitions/cmdline.c                |   99 +++++++
 block/partitions/cmdline.h                |    2 
 include/linux/cmdline-parser.h            |   43 +++
 10 files changed, 452 insertions(+)

Patch

diff -puN /dev/null Documentation/block/cmdline-partition.txt
--- /dev/null
+++ a/Documentation/block/cmdline-partition.txt
@@ -0,0 +1,40 @@ 
+Embedded device command line partition
+=====================================================================
+
+Read block device partition table from command line.
+The partition used for fixed block device (eMMC) embedded device.
+It is no MBR, save storage space. Bootloader can be easily accessed
+by absolute address of data on the block device.
+Users can easily change the partition.
+
+The format for the command line is just like mtdparts:
+
+blkdevparts=<blkdev-def>[;<blkdev-def>]
+  <blkdev-def> := <blkdev-id>:<partdef>[,<partdef>]
+    <partdef> := <size>[@<offset>](part-name)
+
+<blkdev-id>
+    block device disk name, embedded device used fixed block device,
+    it's disk name also fixed. such as: mmcblk0, mmcblk1, mmcblk0boot0.
+
+<size>
+    partition size, in bytes, such as: 512, 1m, 1G.
+
+<offset>
+    partition start address, in bytes.
+
+(part-name)
+    partition name, kernel send uevent with "PARTNAME". application can create
+    a link to block device partition with the name "PARTNAME".
+    user space application can access partition by partition name.
+
+Example:
+    eMMC disk name is "mmcblk0" and "mmcblk0boot0"
+
+  bootargs:
+    'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)'
+
+  dmesg:
+    mmcblk0: p1(data0) p2(data1) p3()
+    mmcblk0boot0: p1(boot) p2(kernel)
+
diff -puN block/partitions/Kconfig~block-support-embedded-device-command-line-partition block/partitions/Kconfig
--- a/block/partitions/Kconfig~block-support-embedded-device-command-line-partition
+++ a/block/partitions/Kconfig
@@ -260,3 +260,10 @@  config SYSV68_PARTITION
 	  partition table format used by Motorola Delta machines (using
 	  sysv68).
 	  Otherwise, say N.
+
+config CMDLINE_PARTITION
+	bool "Command line partition support" if PARTITION_ADVANCED
+	select CMDLINE_PARSER
+	help
+	  Say Y here if you would read the partitions table from bootargs.
+	  The format for the command line is just like mtdparts.
diff -puN block/partitions/Makefile~block-support-embedded-device-command-line-partition block/partitions/Makefile
--- a/block/partitions/Makefile~block-support-embedded-device-command-line-partition
+++ a/block/partitions/Makefile
@@ -8,6 +8,7 @@  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-$(CONFIG_CMDLINE_PARTITION) += cmdline.o
 obj-$(CONFIG_MAC_PARTITION) += mac.o
 obj-$(CONFIG_LDM_PARTITION) += ldm.o
 obj-$(CONFIG_MSDOS_PARTITION) += msdos.o
diff -puN block/partitions/check.c~block-support-embedded-device-command-line-partition block/partitions/check.c
--- a/block/partitions/check.c~block-support-embedded-device-command-line-partition
+++ a/block/partitions/check.c
@@ -34,6 +34,7 @@ 
 #include "efi.h"
 #include "karma.h"
 #include "sysv68.h"
+#include "cmdline.h"
 
 int warn_no_part = 1; /*This is ugly: should make genhd removable media aware*/
 
@@ -65,6 +66,9 @@  static int (*check_part[])(struct parsed
 	adfspart_check_ADFS,
 #endif
 
+#ifdef CONFIG_CMDLINE_PARTITION
+	cmdline_partition,
+#endif
 #ifdef CONFIG_EFI_PARTITION
 	efi_partition,		/* this must come before msdos */
 #endif
diff -puN /dev/null block/partitions/cmdline.c
--- /dev/null
+++ a/block/partitions/cmdline.c
@@ -0,0 +1,99 @@ 
+/*
+ * Copyright (C) 2013 HUAWEI
+ * Author: Cai Zhiyong <caizhiyong@huawei.com>
+ *
+ * Read block device partition table from command line.
+ * The partition used for fixed block device (eMMC) embedded device.
+ * It is no MBR, save storage space. Bootloader can be easily accessed
+ * by absolute address of data on the block device.
+ * Users can easily change the partition.
+ *
+ * The format for the command line is just like mtdparts.
+ *
+ * Verbose config please reference "Documentation/block/cmdline-partition.txt"
+ *
+ */
+
+#include <linux/cmdline-parser.h>
+
+#include "check.h"
+#include "cmdline.h"
+
+static char *cmdline;
+static struct cmdline_parts *bdev_parts;
+
+static int add_part(int slot, struct cmdline_subpart *subpart, void *param)
+{
+	int label_min;
+	struct partition_meta_info *info;
+	char tmp[sizeof(info->volname) + 4];
+	struct parsed_partitions *state = (struct parsed_partitions *)param;
+
+	if (slot >= state->limit)
+		return 1;
+
+	put_partition(state, slot, subpart->from >> 9,
+		      subpart->size >> 9);
+
+	info = &state->parts[slot].info;
+
+	label_min = min_t(int, sizeof(info->volname) - 1,
+			  sizeof(subpart->name));
+	strncpy(info->volname, subpart->name, label_min);
+	info->volname[label_min] = '\0';
+
+	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
+	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+
+	state->parts[slot].has_info = true;
+
+	return 0;
+}
+
+static int __init cmdline_parts_setup(char *s)
+{
+	cmdline = s;
+	return 1;
+}
+__setup("blkdevparts=", cmdline_parts_setup);
+
+/*
+ * Purpose: allocate cmdline partitions.
+ * Returns:
+ * -1 if unable to read the partition table
+ *  0 if this isn't our partition table
+ *  1 if successful
+ */
+int cmdline_partition(struct parsed_partitions *state)
+{
+	sector_t disk_size;
+	char bdev[BDEVNAME_SIZE];
+	struct cmdline_parts *parts;
+
+	if (cmdline) {
+		if (bdev_parts)
+			cmdline_parts_free(&bdev_parts);
+
+		if (cmdline_parts_parse(&bdev_parts, cmdline)) {
+			cmdline = NULL;
+			return -1;
+		}
+		cmdline = NULL;
+	}
+
+	if (!bdev_parts)
+		return 0;
+
+	bdevname(state->bdev, bdev);
+	parts = cmdline_parts_find(bdev_parts, bdev);
+	if (!parts)
+		return 0;
+
+	disk_size = get_capacity(state->bdev->bd_disk) << 9;
+
+	cmdline_parts_set(parts, disk_size, 1, add_part, (void *)state);
+
+	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+
+	return 1;
+}
diff -puN /dev/null block/partitions/cmdline.h
--- /dev/null
+++ a/block/partitions/cmdline.h
@@ -0,0 +1,2 @@ 
+
+int cmdline_partition(struct parsed_partitions *state);
diff -puN block/Kconfig~block-support-embedded-device-command-line-partition block/Kconfig
--- a/block/Kconfig~block-support-embedded-device-command-line-partition
+++ a/block/Kconfig
@@ -99,6 +99,12 @@  config BLK_DEV_THROTTLING
 
 	See Documentation/cgroups/blkio-controller.txt for more information.
 
+config CMDLINE_PARSER
+	bool "Block device command line partition parser"
+	default n
+	---help---
+	Parsing command line, get the partitions information.
+
 menu "Partition Types"
 
 source "block/partitions/Kconfig"
diff -puN block/Makefile~block-support-embedded-device-command-line-partition block/Makefile
--- a/block/Makefile~block-support-embedded-device-command-line-partition
+++ a/block/Makefile
@@ -18,3 +18,4 @@  obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched
 
 obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
 obj-$(CONFIG_BLK_DEV_INTEGRITY)	+= blk-integrity.o
+obj-$(CONFIG_CMDLINE_PARSER)	+= cmdline-parser.o
diff -puN /dev/null block/cmdline-parser.c
--- /dev/null
+++ a/block/cmdline-parser.c
@@ -0,0 +1,249 @@ 
+/*
+ * Parse command line, get partition information
+ *
+ * Written by Cai Zhiyong <caizhiyong@huawei.com>
+ *
+ */
+#include <linux/buffer_head.h>
+#include <linux/module.h>
+#include <linux/cmdline-parser.h>
+
+static int parse_subpart(struct cmdline_subpart **subpart, char *partdef)
+{
+	int ret = 0;
+	struct cmdline_subpart *new_subpart;
+
+	*subpart = NULL;
+
+	new_subpart = kzalloc(sizeof(struct cmdline_subpart), GFP_KERNEL);
+	if (!new_subpart)
+		return -ENOMEM;
+
+	if (*partdef == '-') {
+		new_subpart->size = (sector_t)(~0ULL);
+		partdef++;
+	} else {
+		new_subpart->size = (sector_t)memparse(partdef, &partdef);
+		if (new_subpart->size < (sector_t)PAGE_SIZE) {
+			pr_warn("cmdline partition size is invalid.");
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	if (*partdef == '@') {
+		partdef++;
+		new_subpart->from = (sector_t)memparse(partdef, &partdef);
+	} else {
+		new_subpart->from = (sector_t)(~0ULL);
+	}
+
+	if (*partdef == '(') {
+		int length;
+		char *next = strchr(++partdef, ')');
+
+		if (!next) {
+			pr_warn("cmdline partition format is invalid.");
+			ret = -EINVAL;
+			goto fail;
+		}
+
+		length = min_t(int, next - partdef,
+			       sizeof(new_subpart->name) - 1);
+		strncpy(new_subpart->name, partdef, length);
+		new_subpart->name[length] = '\0';
+
+		partdef = ++next;
+	} else
+		new_subpart->name[0] = '\0';
+
+	new_subpart->flags = 0;
+
+	if (!strncmp(partdef, "ro", 2)) {
+		new_subpart->flags |= PF_RDONLY;
+		partdef += 2;
+	}
+
+	if (!strncmp(partdef, "lk", 2)) {
+		new_subpart->flags |= PF_POWERUP_LOCK;
+		partdef += 2;
+	}
+
+	*subpart = new_subpart;
+	return 0;
+fail:
+	kfree(new_subpart);
+	return ret;
+}
+
+static void free_subpart(struct cmdline_parts *parts)
+{
+	struct cmdline_subpart *subpart;
+
+	while (parts->subpart) {
+		subpart = parts->subpart;
+		parts->subpart = subpart->next_subpart;
+		kfree(subpart);
+	}
+}
+
+static int parse_parts(struct cmdline_parts **parts, const char *bdevdef)
+{
+	int ret = -EINVAL;
+	char *next;
+	int length;
+	struct cmdline_subpart **next_subpart;
+	struct cmdline_parts *newparts;
+	char buf[BDEVNAME_SIZE + 32 + 4];
+
+	*parts = NULL;
+
+	newparts = kzalloc(sizeof(struct cmdline_parts), GFP_KERNEL);
+	if (!newparts)
+		return -ENOMEM;
+
+	next = strchr(bdevdef, ':');
+	if (!next) {
+		pr_warn("cmdline partition has no block device.");
+		goto fail;
+	}
+
+	length = min_t(int, next - bdevdef, sizeof(newparts->name) - 1);
+	strncpy(newparts->name, bdevdef, length);
+	newparts->name[length] = '\0';
+	newparts->nr_subparts = 0;
+
+	next_subpart = &newparts->subpart;
+
+	while (next && *(++next)) {
+		bdevdef = next;
+		next = strchr(bdevdef, ',');
+
+		length = (!next) ? (sizeof(buf) - 1) :
+			min_t(int, next - bdevdef, sizeof(buf) - 1);
+
+		strncpy(buf, bdevdef, length);
+		buf[length] = '\0';
+
+		ret = parse_subpart(next_subpart, buf);
+		if (ret)
+			goto fail;
+
+		newparts->nr_subparts++;
+		next_subpart = &(*next_subpart)->next_subpart;
+	}
+
+	if (!newparts->subpart) {
+		pr_warn("cmdline partition has no valid partition.");
+		goto fail;
+	}
+
+	*parts = newparts;
+
+	return 0;
+fail:
+	free_subpart(newparts);
+	kfree(newparts);
+	return ret;
+}
+
+void cmdline_parts_free(struct cmdline_parts **parts)
+{
+	struct cmdline_parts *next_parts;
+
+	while (*parts) {
+		next_parts = (*parts)->next_parts;
+		free_subpart(*parts);
+		kfree(*parts);
+		*parts = next_parts;
+	}
+}
+
+int cmdline_parts_parse(struct cmdline_parts **parts, const char *cmdline)
+{
+	int ret;
+	char *buf;
+	char *pbuf;
+	char *next;
+	struct cmdline_parts **next_parts;
+
+	*parts = NULL;
+
+	next = pbuf = buf = kstrdup(cmdline, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	next_parts = parts;
+
+	while (next && *pbuf) {
+		next = strchr(pbuf, ';');
+		if (next)
+			*next = '\0';
+
+		ret = parse_parts(next_parts, pbuf);
+		if (ret)
+			goto fail;
+
+		if (next)
+			pbuf = ++next;
+
+		next_parts = &(*next_parts)->next_parts;
+	}
+
+	if (!*parts) {
+		pr_warn("cmdline partition has no valid partition.");
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	ret = 0;
+done:
+	kfree(buf);
+	return ret;
+
+fail:
+	cmdline_parts_free(parts);
+	goto done;
+}
+
+struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
+					 const char *bdev)
+{
+	while (parts && strncmp(bdev, parts->name, sizeof(parts->name)))
+		parts = parts->next_parts;
+	return parts;
+}
+
+/*
+ *  add_part()
+ *    0 success.
+ *    1 can not add so many partitions.
+ */
+void cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
+		       int slot,
+		       int (*add_part)(int, struct cmdline_subpart *, void *),
+		       void *param)
+
+{
+	sector_t from = 0;
+	struct cmdline_subpart *subpart;
+
+	for (subpart = parts->subpart; subpart;
+	     subpart = subpart->next_subpart, slot++) {
+		if (subpart->from == (sector_t)(~0ULL))
+			subpart->from = from;
+		else
+			from = subpart->from;
+
+		if (from >= disk_size)
+			break;
+
+		if (subpart->size > (disk_size - from))
+			subpart->size = disk_size - from;
+
+		from += subpart->size;
+
+		if (add_part(slot, subpart, param))
+			break;
+	}
+}
diff -puN /dev/null include/linux/cmdline-parser.h
--- /dev/null
+++ a/include/linux/cmdline-parser.h
@@ -0,0 +1,43 @@ 
+/*
+ * Parsing command line, get the partitions information.
+ *
+ * Written by Cai Zhiyong <caizhiyong@huawei.com>
+ *
+ */
+#ifndef CMDLINEPARSEH
+#define CMDLINEPARSEH
+
+#include <linux/blkdev.h>
+
+/* partition flags */
+#define PF_RDONLY                   0x01 /* Device is read only */
+#define PF_POWERUP_LOCK             0x02 /* Always locked after reset */
+
+struct cmdline_subpart {
+	char name[BDEVNAME_SIZE]; /* partition name, such as 'rootfs' */
+	sector_t from;
+	sector_t size;
+	int flags;
+	struct cmdline_subpart *next_subpart;
+};
+
+struct cmdline_parts {
+	char name[BDEVNAME_SIZE]; /* block device, such as 'mmcblk0' */
+	unsigned int nr_subparts;
+	struct cmdline_subpart *subpart;
+	struct cmdline_parts *next_parts;
+};
+
+void cmdline_parts_free(struct cmdline_parts **parts);
+
+int cmdline_parts_parse(struct cmdline_parts **parts, const char *cmdline);
+
+struct cmdline_parts *cmdline_parts_find(struct cmdline_parts *parts,
+					 const char *bdev);
+
+void cmdline_parts_set(struct cmdline_parts *parts, sector_t disk_size,
+		       int slot,
+		       int (*add_part)(int, struct cmdline_subpart *, void *),
+		       void *param);
+
+#endif /* CMDLINEPARSEH */