99b7db7b8f
fs: brlock vfsmount_lock Use a brlock for the vfsmount lock. It must be taken for write whenever modifying the mount hash or associated fields, and may be taken for read when performing mount hash lookups. A new lock is added for the mnt-id allocator, so it doesn't need to take the heavy vfsmount write-lock. The number of atomics should remain the same for fastpath rlock cases, though code would be slightly slower due to per-cpu access. Scalability is not not be much improved in common cases yet, due to other locks (ie. dcache_lock) getting in the way. However path lookups crossing mountpoints should be one case where scalability is improved (currently requiring the global lock). The slowpath is slower due to use of brlock. On a 64 core, 64 socket, 32 node Altix system (high latency to remote nodes), a simple umount microbenchmark (mount --bind mnt mnt2 ; umount mnt2 loop 1000 times), before this patch it took 6.8s, afterwards took 7.1s, about 5% slower. Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
103 lines
2.4 KiB
C
103 lines
2.4 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 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 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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