ee3ad542dd
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 <wad@chromium.org>
Review URL: http://codereview.chromium.org/2020011
Change-Id: I92bd53432a11241228d2e5ac89a3b20d19b05a31
[AmitP: Refactored the original changes based on upstream changes,
commit e52347bd66 ("Documentation/admin-guide: split the kernel parameter list to a separate file")]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
73 lines
1.3 KiB
C
73 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/kernel.h>
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#include <linux/blkdev.h>
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#include <linux/init.h>
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#include <linux/syscalls.h>
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#include <linux/unistd.h>
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#include <linux/slab.h>
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#include <linux/mount.h>
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#include <linux/major.h>
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#include <linux/root_dev.h>
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void change_floppy(char *fmt, ...);
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void mount_block_root(char *name, int flags);
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void mount_root(void);
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extern int root_mountflags;
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static inline int create_dev(char *name, dev_t dev)
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{
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ksys_unlink(name);
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return ksys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
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}
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static inline u32 bstat(char *name)
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{
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struct kstat stat;
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if (vfs_stat(name, &stat) != 0)
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return 0;
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if (!S_ISBLK(stat.mode))
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return 0;
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return stat.rdev;
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}
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#ifdef CONFIG_BLK_DEV_RAM
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int __init rd_load_disk(int n);
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int __init rd_load_image(char *from);
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#else
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static inline int rd_load_disk(int n) { return 0; }
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static inline int rd_load_image(char *from) { return 0; }
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#endif
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#ifdef CONFIG_BLK_DEV_INITRD
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bool __init initrd_load(void);
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#else
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static inline bool initrd_load(void) { return false; }
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#endif
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#ifdef CONFIG_BLK_DEV_MD
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void md_run_setup(void);
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#else
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static inline void md_run_setup(void) {}
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#endif
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#ifdef CONFIG_BLK_DEV_DM
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void dm_run_setup(void);
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#else
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static inline void dm_run_setup(void) {}
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#endif
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