android_kernel_xiaomi_sm8350/include/linux/raid/md.h
Dan Williams b5470dc5fc md: resolve external metadata handling deadlock in md_allow_write
md_allow_write() marks the metadata dirty while holding mddev->lock and then
waits for the write to complete.  For externally managed metadata this causes a
deadlock as userspace needs to take the lock to communicate that the metadata
update has completed.

Change md_allow_write() in the 'external' case to start the 'mark active'
operation and then return -EAGAIN.  The expected side effects while waiting for
userspace to write 'active' to 'array_state' are holding off reshape (code
currently handles -ENOMEM), cause some 'stripe_cache_size' change requests to
fail, cause some GET_BITMAP_FILE ioctl requests to fall back to GFP_NOIO, and
cause updates to 'raid_disks' to fail.  Except for 'stripe_cache_size' changes
these failures can be mitigated by coordinating with mdmon.

md_write_start() still prevents writes from occurring until the metadata
handler has had a chance to take action as it unconditionally waits for
MD_CHANGE_CLEAN to be cleared.

[neilb@suse.de: return -EAGAIN, try GFP_NOIO]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2008-06-30 17:18:19 -07:00

104 lines
3.4 KiB
C

/*
md.h : Multiple Devices driver for Linux
Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
Copyright (C) 1994-96 Marc ZYNGIER
<zyngier@ufr-info-p7.ibp.fr> or
<maz@gloups.fdn.fr>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
You should have received a copy of the GNU General Public License
(for example /usr/src/linux/COPYING); if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef _MD_H
#define _MD_H
#include <linux/blkdev.h>
#include <linux/major.h>
#include <linux/ioctl.h>
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/hdreg.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/smp_lock.h>
#include <linux/delay.h>
#include <net/checksum.h>
#include <linux/random.h>
#include <linux/kernel_stat.h>
#include <asm/io.h>
#include <linux/completion.h>
#include <linux/mempool.h>
#include <linux/list.h>
#include <linux/reboot.h>
#include <linux/vmalloc.h>
#include <linux/blkpg.h>
#include <linux/bio.h>
/*
* 'md_p.h' holds the 'physical' layout of RAID devices
* 'md_u.h' holds the user <=> kernel API
*
* 'md_k.h' holds kernel internal definitions
*/
#include <linux/raid/md_p.h>
#include <linux/raid/md_u.h>
#include <linux/raid/md_k.h>
#ifdef CONFIG_MD
/*
* Different major versions are not compatible.
* Different minor versions are only downward compatible.
* Different patchlevel versions are downward and upward compatible.
*/
#define MD_MAJOR_VERSION 0
#define MD_MINOR_VERSION 90
/*
* MD_PATCHLEVEL_VERSION indicates kernel functionality.
* >=1 means different superblock formats are selectable using SET_ARRAY_INFO
* and major_version/minor_version accordingly
* >=2 means that Internal bitmaps are supported by setting MD_SB_BITMAP_PRESENT
* in the super status byte
* >=3 means that bitmap superblock version 4 is supported, which uses
* little-ending representation rather than host-endian
*/
#define MD_PATCHLEVEL_VERSION 3
extern int mdp_major;
extern int register_md_personality (struct mdk_personality *p);
extern int unregister_md_personality (struct mdk_personality *p);
extern mdk_thread_t * md_register_thread (void (*run) (mddev_t *mddev),
mddev_t *mddev, const char *name);
extern void md_unregister_thread (mdk_thread_t *thread);
extern void md_wakeup_thread(mdk_thread_t *thread);
extern void md_check_recovery(mddev_t *mddev);
extern void md_write_start(mddev_t *mddev, struct bio *bi);
extern void md_write_end(mddev_t *mddev);
extern void md_handle_safemode(mddev_t *mddev);
extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
extern void md_error (mddev_t *mddev, mdk_rdev_t *rdev);
extern void md_unplug_mddev(mddev_t *mddev);
extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
sector_t sector, int size, struct page *page);
extern void md_super_wait(mddev_t *mddev);
extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
struct page *page, int rw);
extern void md_do_sync(mddev_t *mddev);
extern void md_new_event(mddev_t *mddev);
extern int md_allow_write(mddev_t *mddev);
extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
#endif /* CONFIG_MD */
#endif