afd4669f0a
This patch changes umount(2) flow to wait for delayed fput/mntput. Meanwhile,
we can still see unclosed name spaces which can trigger filesystem panic due
to released device illustrated below. (i.e., ext4 with errors=panic)
So, it introduces fs->umount_end() to change filesystem behavior like
error=remount-ro in ext4.
WARN: DO NOT upstream!
This is only related to Android reboot procedure, and resolves the below
issue where a kernel panic happens when a living filesystem tries to access
dead block device after device_shutdown done by kernel_restart.
Term: namespace(mnt_get_count())
1. create_new_namespaces() creates ns1 and ns2,
/data(1) ns1(1) ns2(1)
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---------------------
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sb->s_active = 3
2. after binder_proc_clear_zombies() for ns2 and ns1 triggers
- delayed_fput()
- delayed_mntput_work(ns2)
/data(1) ns1(1)
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----------
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sb->s_active = 2
3. umount() for /data is successed.
ns1(1)
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sb->s_active = 1
4. device_shutdown() by init
5. - delayed_mntput_work(ns1)
- put_super(), since sb->s_active = 0
- -EIO
Bug: 63981945
Bug: 65481582
Bug: 72236603
Change-Id: I7db02f480cc839bf9c245e078164a8168ea0d88b
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
93 lines
2.1 KiB
C
93 lines
2.1 KiB
C
/*
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* Wrapper functions for accessing the file_struct fd array.
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*/
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#ifndef __LINUX_FILE_H
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#define __LINUX_FILE_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/posix_types.h>
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struct file;
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extern void fput(struct file *);
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extern void fput_many(struct file *, unsigned int);
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struct file_operations;
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struct vfsmount;
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struct dentry;
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struct path;
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extern struct file *alloc_file(struct path *, fmode_t mode,
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const struct file_operations *fop);
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static inline void fput_light(struct file *file, int fput_needed)
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{
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if (fput_needed)
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fput(file);
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}
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struct fd {
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struct file *file;
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unsigned int flags;
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};
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#define FDPUT_FPUT 1
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#define FDPUT_POS_UNLOCK 2
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static inline void fdput(struct fd fd)
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{
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if (fd.flags & FDPUT_FPUT)
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fput(fd.file);
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}
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extern struct file *fget(unsigned int fd);
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extern struct file *fget_many(unsigned int fd, unsigned int refs);
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extern struct file *fget_raw(unsigned int fd);
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extern unsigned long __fdget(unsigned int fd);
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extern unsigned long __fdget_raw(unsigned int fd);
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extern unsigned long __fdget_pos(unsigned int fd);
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extern void __f_unlock_pos(struct file *);
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static inline struct fd __to_fd(unsigned long v)
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{
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return (struct fd){(struct file *)(v & ~3),v & 3};
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}
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static inline struct fd fdget(unsigned int fd)
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{
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return __to_fd(__fdget(fd));
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}
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static inline struct fd fdget_raw(unsigned int fd)
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{
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return __to_fd(__fdget_raw(fd));
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}
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static inline struct fd fdget_pos(int fd)
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{
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return __to_fd(__fdget_pos(fd));
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}
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static inline void fdput_pos(struct fd f)
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{
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if (f.flags & FDPUT_POS_UNLOCK)
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__f_unlock_pos(f.file);
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fdput(f);
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}
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extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
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extern int replace_fd(unsigned fd, struct file *file, unsigned flags);
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extern void set_close_on_exec(unsigned int fd, int flag);
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extern bool get_close_on_exec(unsigned int fd);
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extern void put_filp(struct file *);
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extern int get_unused_fd_flags(unsigned flags);
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extern void put_unused_fd(unsigned int fd);
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extern void fd_install(unsigned int fd, struct file *file);
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extern void flush_delayed_fput(void);
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extern void flush_delayed_fput_wait(void);
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extern void __fput_sync(struct file *);
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#endif /* __LINUX_FILE_H */
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