From bad6663f2469fe187641065c9f4e0c0bd0b72faa Mon Sep 17 00:00:00 2001 From: Will Drewry Date: Wed, 9 Jun 2010 17:47:38 -0500 Subject: [PATCH] CHROMIUM: dm: boot time specification of dm= This is a wrap-up of three patches pending upstream approval. I'm bundling them because they are interdependent, and it'll be easier to drop it on rebase later. 1. dm: allow a dm-fs-style device to be shared via dm-ioctl Integrates feedback from Alisdair, Mike, and Kiyoshi. Two main changes occur here: - One function is added which allows for a programmatically created mapped device to be inserted into the dm-ioctl hash table. This binds the device to a name and, optional, uuid which is needed by udev and allows for userspace management of the mapped device. - dm_table_complete() was extended to handle all of the final functional changes required for the table to be operational once called. 2. init: boot to device-mapper targets without an initr* Add a dm= kernel parameter modeled after the md= parameter from do_mounts_md. It allows for device-mapper targets to be configured at boot time for use early in the boot process (as the root device or otherwise). It also replaces /dev/XXX calls with major:minor opportunistically. The format is dm="name uuid ro,table line 1,table line 2,...". The parser expects the comma to be safe to use as a newline substitute but, otherwise, uses the normal separator of space. Some attempt has been made to make it forgiving of additional spaces (using skip_spaces()). A mapped device created during boot will be assigned a minor of 0 and may be access via /dev/dm-0. An example dm-linear root with no uuid may look like: root=/dev/dm-0 dm="lroot none ro, 0 4096 linear /dev/ubdb 0, 4096 4096 linear /dv/ubdc 0" Once udev is started, /dev/dm-0 will become /dev/mapper/lroot. Older upstream threads: http://marc.info/?l=dm-devel&m=127429492521964&w=2 http://marc.info/?l=dm-devel&m=127429499422096&w=2 http://marc.info/?l=dm-devel&m=127429493922000&w=2 Latest upstream threads: https://patchwork.kernel.org/patch/104859/ https://patchwork.kernel.org/patch/104860/ https://patchwork.kernel.org/patch/104861/ BUG: 27175947 Signed-off-by: Will Drewry Review URL: http://codereview.chromium.org/2020011 Change-Id: I92bd53432a11241228d2e5ac89a3b20d19b05a31 --- Documentation/device-mapper/boot.txt | 42 +++ Documentation/kernel-parameters.txt | 6 + drivers/md/dm-ioctl.c | 39 +++ drivers/md/dm-table.c | 1 + include/linux/device-mapper.h | 6 + init/Makefile | 1 + init/do_mounts.c | 1 + init/do_mounts.h | 10 + init/do_mounts_dm.c | 410 +++++++++++++++++++++++++++ 9 files changed, 516 insertions(+) create mode 100644 Documentation/device-mapper/boot.txt create mode 100644 init/do_mounts_dm.c diff --git a/Documentation/device-mapper/boot.txt b/Documentation/device-mapper/boot.txt new file mode 100644 index 000000000000..adcaad5e5e32 --- /dev/null +++ b/Documentation/device-mapper/boot.txt @@ -0,0 +1,42 @@ +Boot time creation of mapped devices +=================================== + +It is possible to configure a device mapper device to act as the root +device for your system in two ways. + +The first is to build an initial ramdisk which boots to a minimal +userspace which configures the device, then pivot_root(8) in to it. + +For simple device mapper configurations, it is possible to boot directly +using the following kernel command line: + +dm=" ,table line 1,...,table line n" + +name = the name to associate with the device + after boot, udev, if used, will use that name to label + the device node. +uuid = may be 'none' or the UUID desired for the device. +ro = may be "ro" or "rw". If "ro", the device and device table will be + marked read-only. + +Each table line may be as normal when using the dmsetup tool except for +two variations: +1. Any use of commas will be interpreted as a newline +2. Quotation marks cannot be escaped and cannot be used without + terminating the dm= argument. + +Unless renamed by udev, the device node created will be dm-0 as the +first minor number for the device-mapper is used during early creation. + +Example +======= + +- Booting to a linear array made up of user-mode linux block devices: + + dm="lroot none 0, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" \ + root=/dev/dm-0 + +Will boot to a rw dm-linear target of 8192 sectors split across two +block devices identified by their major:minor numbers. After boot, udev +will rename this target to /dev/mapper/lroot (depending on the rules). +No uuid was assigned. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 3006ac5bcaa0..2fcbee126d82 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -46,6 +46,7 @@ parameter is applicable: BLACKFIN Blackfin architecture is enabled. CLK Common clock infrastructure is enabled. CMA Contiguous Memory Area support is enabled. + DM Device mapper support is enabled. DRM Direct Rendering Management support is enabled. DYNAMIC_DEBUG Build in debug messages and enable them at runtime EDD BIOS Enhanced Disk Drive Services (EDD) is enabled @@ -745,6 +746,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Disable PIN 1 of APIC timer Can be useful to work around chipset bugs. + dm= [DM] Allows early creation of a device-mapper device. + See Documentation/device-mapper/boot.txt. + + dmasound= [HW,OSS] Sound subsystem buffers + dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, this option disables the debugging code at boot. diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 81a79b739e97..1debe0433ec6 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1849,6 +1849,45 @@ void dm_interface_exit(void) dm_hash_exit(); } + +/** + * dm_ioctl_export - Permanently export a mapped device via the ioctl interface + * @md: Pointer to mapped_device + * @name: Buffer (size DM_NAME_LEN) for name + * @uuid: Buffer (size DM_UUID_LEN) for uuid or NULL if not desired + */ +int dm_ioctl_export(struct mapped_device *md, const char *name, + const char *uuid) +{ + int r = 0; + struct hash_cell *hc; + + if (!md) { + r = -ENXIO; + goto out; + } + + /* The name and uuid can only be set once. */ + mutex_lock(&dm_hash_cells_mutex); + hc = dm_get_mdptr(md); + mutex_unlock(&dm_hash_cells_mutex); + if (hc) { + DMERR("%s: already exported", dm_device_name(md)); + r = -ENXIO; + goto out; + } + + r = dm_hash_insert(name, uuid, md); + if (r) { + DMERR("%s: could not bind to '%s'", dm_device_name(md), name); + goto out; + } + + /* Let udev know we've changed. */ + dm_kobject_uevent(md, KOBJ_CHANGE, dm_get_event_nr(md)); +out: + return r; +} /** * dm_copy_name_and_uuid - Copy mapped device name & uuid into supplied buffers * @md: Pointer to mapped_device diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 3bb00e2738a5..cf52d4cf13f4 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 8b97305578bd..ffc1983c3d26 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -380,6 +380,12 @@ void dm_put(struct mapped_device *md); void dm_set_mdptr(struct mapped_device *md, void *ptr); void *dm_get_mdptr(struct mapped_device *md); +/* + * Export the device via the ioctl interface (uses mdptr). + */ +int dm_ioctl_export(struct mapped_device *md, const char *name, + const char *uuid); + /* * A device can still be used while suspended, but I/O is deferred. */ diff --git a/init/Makefile b/init/Makefile index 692b91f1c1d4..243f61de2cba 100644 --- a/init/Makefile +++ b/init/Makefile @@ -15,6 +15,7 @@ mounts-y := do_mounts.o mounts-$(CONFIG_BLK_DEV_RAM) += do_mounts_rd.o mounts-$(CONFIG_BLK_DEV_INITRD) += do_mounts_initrd.o mounts-$(CONFIG_BLK_DEV_MD) += do_mounts_md.o +mounts-$(CONFIG_BLK_DEV_DM) += do_mounts_dm.o # dependencies on generated files need to be listed explicitly $(obj)/version.o: include/generated/compile.h diff --git a/init/do_mounts.c b/init/do_mounts.c index a2b49f2c1bd8..b3cc00f4bed5 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -551,6 +551,7 @@ void __init prepare_namespace(void) wait_for_device_probe(); md_run_setup(); + dm_run_setup(); if (saved_root_name[0]) { root_device_name = saved_root_name; diff --git a/init/do_mounts.h b/init/do_mounts.h index f5b978a9bb92..09d22862e8c3 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -74,3 +74,13 @@ void md_run_setup(void); static inline void md_run_setup(void) {} #endif + +#ifdef CONFIG_BLK_DEV_DM + +void dm_run_setup(void); + +#else + +static inline void dm_run_setup(void) {} + +#endif diff --git a/init/do_mounts_dm.c b/init/do_mounts_dm.c new file mode 100644 index 000000000000..0fd3411533f3 --- /dev/null +++ b/init/do_mounts_dm.c @@ -0,0 +1,410 @@ +/* do_mounts_dm.c + * Copyright (C) 2010 The Chromium OS Authors + * All Rights Reserved. + * Based on do_mounts_md.c + * + * This file is released under the GPL. + */ +#include +#include +#include + +#include "do_mounts.h" + +#define DM_MAX_NAME 32 +#define DM_MAX_UUID 129 +#define DM_NO_UUID "none" + +#define DM_MSG_PREFIX "init" + +/* Separators used for parsing the dm= argument. */ +#define DM_FIELD_SEP ' ' +#define DM_LINE_SEP ',' + +/* + * When the device-mapper and any targets are compiled into the kernel + * (not a module), one target may be created and used as the root device at + * boot time with the parameters given with the boot line dm=... + * The code for that is here. + */ + +struct dm_setup_target { + sector_t begin; + sector_t length; + char *type; + char *params; + /* simple singly linked list */ + struct dm_setup_target *next; +}; + +static struct { + int minor; + int ro; + char name[DM_MAX_NAME]; + char uuid[DM_MAX_UUID]; + char *targets; + struct dm_setup_target *target; + int target_count; +} dm_setup_args __initdata; + +static __initdata int dm_early_setup; + +static size_t __init get_dm_option(char *str, char **next, char sep) +{ + size_t len = 0; + char *endp = NULL; + + if (!str) + return 0; + + endp = strchr(str, sep); + if (!endp) { /* act like strchrnul */ + len = strlen(str); + endp = str + len; + } else { + len = endp - str; + } + + if (endp == str) + return 0; + + if (!next) + return len; + + if (*endp == 0) { + /* Don't advance past the nul. */ + *next = endp; + } else { + *next = endp + 1; + } + return len; +} + +static int __init dm_setup_args_init(void) +{ + dm_setup_args.minor = 0; + dm_setup_args.ro = 0; + dm_setup_args.target = NULL; + dm_setup_args.target_count = 0; + return 0; +} + +static int __init dm_setup_cleanup(void) +{ + struct dm_setup_target *target = dm_setup_args.target; + struct dm_setup_target *old_target = NULL; + while (target) { + kfree(target->type); + kfree(target->params); + old_target = target; + target = target->next; + kfree(old_target); + dm_setup_args.target_count--; + } + BUG_ON(dm_setup_args.target_count); + return 0; +} + +static char * __init dm_setup_parse_device_args(char *str) +{ + char *next = NULL; + size_t len = 0; + + /* Grab the logical name of the device to be exported to udev */ + len = get_dm_option(str, &next, DM_FIELD_SEP); + if (!len) { + DMERR("failed to parse device name"); + goto parse_fail; + } + len = min(len + 1, sizeof(dm_setup_args.name)); + strlcpy(dm_setup_args.name, str, len); /* includes nul */ + str = skip_spaces(next); + + /* Grab the UUID value or "none" */ + len = get_dm_option(str, &next, DM_FIELD_SEP); + if (!len) { + DMERR("failed to parse device uuid"); + goto parse_fail; + } + len = min(len + 1, sizeof(dm_setup_args.uuid)); + strlcpy(dm_setup_args.uuid, str, len); + str = skip_spaces(next); + + /* Determine if the table/device will be read only or read-write */ + if (!strncmp("ro,", str, 3)) { + dm_setup_args.ro = 1; + } else if (!strncmp("rw,", str, 3)) { + dm_setup_args.ro = 0; + } else { + DMERR("failed to parse table mode"); + goto parse_fail; + } + str = skip_spaces(str + 3); + + return str; + +parse_fail: + return NULL; +} + +static void __init dm_substitute_devices(char *str, size_t str_len) +{ + char *candidate = str; + char *candidate_end = str; + char old_char; + size_t len = 0; + dev_t dev; + + if (str_len < 3) + return; + + while (str && *str) { + candidate = strchr(str, '/'); + if (!candidate) + break; + + /* Avoid embedded slashes */ + if (candidate != str && *(candidate - 1) != DM_FIELD_SEP) { + str = strchr(candidate, DM_FIELD_SEP); + continue; + } + + len = get_dm_option(candidate, &candidate_end, DM_FIELD_SEP); + str = skip_spaces(candidate_end); + if (len < 3 || len > 37) /* name_to_dev_t max; maj:mix min */ + continue; + + /* Temporarily terminate with a nul */ + candidate_end--; + old_char = *candidate_end; + *candidate_end = '\0'; + + DMDEBUG("converting candidate device '%s' to dev_t", candidate); + /* Use the boot-time specific device naming */ + dev = name_to_dev_t(candidate); + *candidate_end = old_char; + + DMDEBUG(" -> %u", dev); + /* No suitable replacement found */ + if (!dev) + continue; + + /* Rewrite the /dev/path as a major:minor */ + len = snprintf(candidate, len, "%u:%u", MAJOR(dev), MINOR(dev)); + if (!len) { + DMERR("error substituting device major/minor."); + break; + } + candidate += len; + /* Pad out with spaces (fixing our nul) */ + while (candidate < candidate_end) + *(candidate++) = DM_FIELD_SEP; + } +} + +static int __init dm_setup_parse_targets(char *str) +{ + char *next = NULL; + size_t len = 0; + struct dm_setup_target **target = NULL; + + /* Targets are defined as per the table format but with a + * comma as a newline separator. */ + target = &dm_setup_args.target; + while (str && *str) { + *target = kzalloc(sizeof(struct dm_setup_target), GFP_KERNEL); + if (!*target) { + DMERR("failed to allocate memory for target %d", + dm_setup_args.target_count); + goto parse_fail; + } + dm_setup_args.target_count++; + + (*target)->begin = simple_strtoull(str, &next, 10); + if (!next || *next != DM_FIELD_SEP) { + DMERR("failed to parse starting sector for target %d", + dm_setup_args.target_count - 1); + goto parse_fail; + } + str = skip_spaces(next + 1); + + (*target)->length = simple_strtoull(str, &next, 10); + if (!next || *next != DM_FIELD_SEP) { + DMERR("failed to parse length for target %d", + dm_setup_args.target_count - 1); + goto parse_fail; + } + str = skip_spaces(next + 1); + + len = get_dm_option(str, &next, DM_FIELD_SEP); + if (!len || + !((*target)->type = kstrndup(str, len, GFP_KERNEL))) { + DMERR("failed to parse type for target %d", + dm_setup_args.target_count - 1); + goto parse_fail; + } + str = skip_spaces(next); + + len = get_dm_option(str, &next, DM_LINE_SEP); + if (!len || + !((*target)->params = kstrndup(str, len, GFP_KERNEL))) { + DMERR("failed to parse params for target %d", + dm_setup_args.target_count - 1); + goto parse_fail; + } + str = skip_spaces(next); + + /* Before moving on, walk through the copied target and + * attempt to replace all /dev/xxx with the major:minor number. + * It may not be possible to resolve them traditionally at + * boot-time. */ + dm_substitute_devices((*target)->params, len); + + target = &((*target)->next); + } + DMDEBUG("parsed %d targets", dm_setup_args.target_count); + + return 0; + +parse_fail: + return 1; +} + +/* + * Parse the command-line parameters given our kernel, but do not + * actually try to invoke the DM device now; that is handled by + * dm_setup_drive after the low-level disk drivers have initialised. + * dm format is as follows: + * dm="name uuid fmode,[table line 1],[table line 2],..." + * May be used with root=/dev/dm-0 as it always uses the first dm minor. + */ + +static int __init dm_setup(char *str) +{ + dm_setup_args_init(); + + str = dm_setup_parse_device_args(str); + if (!str) { + DMDEBUG("str is NULL"); + goto parse_fail; + } + + /* Target parsing is delayed until we have dynamic memory */ + dm_setup_args.targets = str; + + printk(KERN_INFO "dm: will configure '%s' on dm-%d\n", + dm_setup_args.name, dm_setup_args.minor); + + dm_early_setup = 1; + return 1; + +parse_fail: + printk(KERN_WARNING "dm: Invalid arguments supplied to dm=.\n"); + return 0; +} + + +static void __init dm_setup_drive(void) +{ + struct mapped_device *md = NULL; + struct dm_table *table = NULL; + struct dm_setup_target *target; + char *uuid = dm_setup_args.uuid; + fmode_t fmode = FMODE_READ; + + /* Finish parsing the targets. */ + if (dm_setup_parse_targets(dm_setup_args.targets)) + goto parse_fail; + + if (dm_create(dm_setup_args.minor, &md)) { + DMDEBUG("failed to create the device"); + goto dm_create_fail; + } + DMDEBUG("created device '%s'", dm_device_name(md)); + + /* In addition to flagging the table below, the disk must be + * set explicitly ro/rw. */ + set_disk_ro(dm_disk(md), dm_setup_args.ro); + + if (!dm_setup_args.ro) + fmode |= FMODE_WRITE; + if (dm_table_create(&table, fmode, dm_setup_args.target_count, md)) { + DMDEBUG("failed to create the table"); + goto dm_table_create_fail; + } + + target = dm_setup_args.target; + while (target) { + DMINFO("adding target '%llu %llu %s %s'", + (unsigned long long) target->begin, + (unsigned long long) target->length, target->type, + target->params); + if (dm_table_add_target(table, target->type, target->begin, + target->length, target->params)) { + DMDEBUG("failed to add the target to the table"); + goto add_target_fail; + } + target = target->next; + } + + if (dm_table_complete(table)) { + DMDEBUG("failed to complete the table"); + goto table_complete_fail; + } + + /* Suspend the device so that we can bind it to the table. */ + if (dm_suspend(md, 0)) { + DMDEBUG("failed to suspend the device pre-bind"); + goto suspend_fail; + } + + /* Bind the table to the device. This is the only way to associate + * md->map with the table and set the disk capacity directly. */ + if (dm_swap_table(md, table)) { /* should return NULL. */ + DMDEBUG("failed to bind the device to the table"); + goto table_bind_fail; + } + + /* Finally, resume and the device should be ready. */ + if (dm_resume(md)) { + DMDEBUG("failed to resume the device"); + goto resume_fail; + } + + /* Export the dm device via the ioctl interface */ + if (!strcmp(DM_NO_UUID, dm_setup_args.uuid)) + uuid = NULL; + if (dm_ioctl_export(md, dm_setup_args.name, uuid)) { + DMDEBUG("failed to export device with given name and uuid"); + goto export_fail; + } + printk(KERN_INFO "dm: dm-%d is ready\n", dm_setup_args.minor); + + dm_setup_cleanup(); + return; + +export_fail: +resume_fail: +table_bind_fail: +suspend_fail: +table_complete_fail: +add_target_fail: + dm_table_put(table); +dm_table_create_fail: + dm_put(md); +dm_create_fail: + dm_setup_cleanup(); +parse_fail: + printk(KERN_WARNING "dm: starting dm-%d (%s) failed\n", + dm_setup_args.minor, dm_setup_args.name); +} + +__setup("dm=", dm_setup); + +void __init dm_run_setup(void) +{ + if (!dm_early_setup) + return; + printk(KERN_INFO "dm: attempting early device configuration.\n"); + dm_setup_drive(); +}