3064c3563b
Rather than playing silly buggers with vfsmount refcounts, just have acct_on() ask fs/namespace.c for internal clone of file->f_path.mnt and replace it with said clone. Then attach the pin to original vfsmount. Voila - the clone will be alive until the file gets closed, making sure that underlying superblock remains active, etc., and we can drop the original vfsmount, so that it's not kept busy. If the file lives until the final mntput of the original vfsmount, we'll notice that there's an fs_pin (one in bsd_acct_struct that holds that file) and mnt_pin_kill() will take it out. Since ->kill() is synchronous, we won't proceed past that point until these files are closed (and private clones of our vfsmount are gone), so we get the same ordering warranties we used to get. mnt_pin()/mnt_unpin()/->mnt_pinned is gone now, and good riddance - it never became usable outside of kernel/acct.c (and racy wrt umount even there). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/*
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*
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* Definitions for mount interface. This describes the in the kernel build
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* linkedlist with mounted filesystems.
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*
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* Author: Marco van Wieringen <mvw@planets.elm.net>
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*
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*/
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#ifndef _LINUX_MOUNT_H
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#define _LINUX_MOUNT_H
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/nodemask.h>
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#include <linux/spinlock.h>
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#include <linux/seqlock.h>
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#include <linux/atomic.h>
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struct super_block;
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struct vfsmount;
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struct dentry;
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struct mnt_namespace;
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#define MNT_NOSUID 0x01
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#define MNT_NODEV 0x02
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#define MNT_NOEXEC 0x04
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#define MNT_NOATIME 0x08
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#define MNT_NODIRATIME 0x10
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#define MNT_RELATIME 0x20
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#define MNT_READONLY 0x40 /* does the user want this to be r/o? */
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#define MNT_SHRINKABLE 0x100
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#define MNT_WRITE_HOLD 0x200
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#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
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#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
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/*
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* MNT_SHARED_MASK is the set of flags that should be cleared when a
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* mount becomes shared. Currently, this is only the flag that says a
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* mount cannot be bind mounted, since this is how we create a mount
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* that shares events with another mount. If you add a new MNT_*
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* flag, consider how it interacts with shared mounts.
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*/
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#define MNT_SHARED_MASK (MNT_UNBINDABLE)
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#define MNT_PROPAGATION_MASK (MNT_SHARED | MNT_UNBINDABLE)
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#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
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MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)
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#define MNT_INTERNAL 0x4000
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#define MNT_LOCK_READONLY 0x400000
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#define MNT_LOCKED 0x800000
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#define MNT_DOOMED 0x1000000
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#define MNT_SYNC_UMOUNT 0x2000000
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#define MNT_MARKED 0x4000000
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struct vfsmount {
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struct dentry *mnt_root; /* root of the mounted tree */
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struct super_block *mnt_sb; /* pointer to superblock */
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int mnt_flags;
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};
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struct file; /* forward dec */
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struct path;
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extern int mnt_want_write(struct vfsmount *mnt);
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extern int mnt_want_write_file(struct file *file);
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extern int mnt_clone_write(struct vfsmount *mnt);
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extern void mnt_drop_write(struct vfsmount *mnt);
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extern void mnt_drop_write_file(struct file *file);
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extern void mntput(struct vfsmount *mnt);
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extern struct vfsmount *mntget(struct vfsmount *mnt);
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extern struct vfsmount *mnt_clone_internal(struct path *path);
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extern int __mnt_is_readonly(struct vfsmount *mnt);
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struct file_system_type;
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extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
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int flags, const char *name,
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void *data);
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extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
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extern void mark_mounts_for_expiry(struct list_head *mounts);
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extern dev_t name_to_dev_t(char *name);
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#endif /* _LINUX_MOUNT_H */
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