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93b270f76e
There are two cases when we call flush_disk.
In one, the device has disappeared (check_disk_change) so any
data will hold becomes irrelevant.
In the oter, the device has changed size (check_disk_size_change)
so data we hold may be irrelevant.
In both cases it makes sense to discard any 'clean' buffers,
so they will be read back from the device if needed.
In the former case it makes sense to discard 'dirty' buffers
as there will never be anywhere safe to write the data. In the
second case it *does*not* make sense to discard dirty buffers
as that will lead to file system corruption when you simply enlarge
the containing devices.
flush_disk calls __invalidate_devices.
__invalidate_device calls both invalidate_inodes and invalidate_bdev.
invalidate_inodes *does* discard I_DIRTY inodes and this does lead
to fs corruption.
invalidate_bev *does*not* discard dirty pages, but I don't really care
about that at present.
So this patch adds a flag to __invalidate_device (calling it
__invalidate_device2) to indicate whether dirty buffers should be
killed, and this is passed to invalidate_inodes which can choose to
skip dirty inodes.
flusk_disk then passes true from check_disk_change and false from
check_disk_size_change.
dm avoids tripping over this problem by calling i_size_write directly
rathher than using check_disk_size_change.
md does use check_disk_size_change and so is affected.
This regression was introduced by commit 608aeef17a which causes
check_disk_size_change to call flush_disk, so it is suitable for any
kernel since 2.6.27.
Cc: stable@kernel.org
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Andrew Patterson <andrew.patterson@hp.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NeilBrown <neilb@suse.de>
116 lines
2.8 KiB
C
116 lines
2.8 KiB
C
/* fs/ internal definitions
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*
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* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/lglock.h>
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struct super_block;
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struct linux_binprm;
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struct path;
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/*
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* block_dev.c
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*/
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#ifdef CONFIG_BLOCK
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extern struct super_block *blockdev_superblock;
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extern void __init bdev_cache_init(void);
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static inline int sb_is_blkdev_sb(struct super_block *sb)
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{
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return sb == blockdev_superblock;
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}
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extern int __sync_blockdev(struct block_device *bdev, int wait);
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#else
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static inline void bdev_cache_init(void)
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{
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}
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static inline int sb_is_blkdev_sb(struct super_block *sb)
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{
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return 0;
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}
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static inline int __sync_blockdev(struct block_device *bdev, int wait)
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{
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return 0;
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}
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#endif
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/*
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* char_dev.c
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*/
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extern void __init chrdev_init(void);
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/*
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* exec.c
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*/
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extern int check_unsafe_exec(struct linux_binprm *);
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/*
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* namespace.c
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*/
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extern int copy_mount_options(const void __user *, unsigned long *);
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extern int copy_mount_string(const void __user *, char **);
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extern void free_vfsmnt(struct vfsmount *);
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extern struct vfsmount *alloc_vfsmnt(const char *);
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extern unsigned int mnt_get_count(struct vfsmount *mnt);
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extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
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extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
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struct vfsmount *);
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extern void release_mounts(struct list_head *);
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extern void umount_tree(struct vfsmount *, int, struct list_head *);
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extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
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extern int finish_automount(struct vfsmount *, struct path *);
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extern void mnt_make_longterm(struct vfsmount *);
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extern void mnt_make_shortterm(struct vfsmount *);
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extern void __init mnt_init(void);
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DECLARE_BRLOCK(vfsmount_lock);
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/*
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* fs_struct.c
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*/
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extern void chroot_fs_refs(struct path *, struct path *);
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/*
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* file_table.c
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*/
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extern void file_sb_list_add(struct file *f, struct super_block *sb);
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extern void file_sb_list_del(struct file *f);
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extern void mark_files_ro(struct super_block *);
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extern struct file *get_empty_filp(void);
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/*
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* super.c
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*/
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extern int do_remount_sb(struct super_block *, int, void *, int);
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extern void __put_super(struct super_block *sb);
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extern void put_super(struct super_block *sb);
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/*
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* open.c
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*/
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struct nameidata;
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extern struct file *nameidata_to_filp(struct nameidata *);
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extern void release_open_intent(struct nameidata *);
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/*
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* inode.c
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*/
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extern int get_nr_dirty_inodes(void);
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extern void evict_inodes(struct super_block *);
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extern int invalidate_inodes(struct super_block *, bool);
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