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eb6ef3df4f
I've noticed significant locking contention in memory reclaimer around sb_lock inside grab_super_passive(). Grab_super_passive() is called from two places: in icache/dcache shrinkers (function super_cache_scan) and from writeback (function __writeback_inodes_wb). Both are required for progress in memory allocator. Grab_super_passive() acquires sb_lock to increment sb->s_count and check sb->s_instances. It seems sb->s_umount locked for read is enough here: super-block deactivation always runs under sb->s_umount locked for write. Protecting super-block itself isn't a problem: in super_cache_scan() sb is protected by shrinker_rwsem: it cannot be freed if its slab shrinkers are still active. Inside writeback super-block comes from inode from bdi writeback list under wb->list_lock. This patch removes locking sb_lock and checks s_instances under s_umount: generic_shutdown_super() unlinks it under sb->s_umount locked for write. New variant is called trylock_super() and since it only locks semaphore, callers must call up_read(&sb->s_umount) instead of drop_super(sb) when they're done. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
154 lines
3.5 KiB
C
154 lines
3.5 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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struct super_block;
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struct file_system_type;
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struct linux_binprm;
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struct path;
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struct mount;
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struct shrink_control;
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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 void __init bdev_cache_init(void);
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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 __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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* buffer.c
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*/
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extern void guard_bio_eod(int rw, struct bio *bio);
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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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* namei.c
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*/
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extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
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extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
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const char *, unsigned int, struct path *);
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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 char *copy_mount_string(const void __user *);
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extern struct vfsmount *lookup_mnt(struct path *);
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extern int finish_automount(struct vfsmount *, struct path *);
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extern int sb_prepare_remount_readonly(struct super_block *);
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extern void __init mnt_init(void);
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extern int __mnt_want_write(struct vfsmount *);
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extern int __mnt_want_write_file(struct file *);
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extern void __mnt_drop_write(struct vfsmount *);
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extern void __mnt_drop_write_file(struct file *);
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/*
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* fs_struct.c
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*/
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extern void chroot_fs_refs(const struct path *, const struct path *);
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/*
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* file_table.c
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*/
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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 bool trylock_super(struct super_block *sb);
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extern struct dentry *mount_fs(struct file_system_type *,
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int, const char *, void *);
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extern struct super_block *user_get_super(dev_t);
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/*
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* open.c
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*/
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struct open_flags {
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int open_flag;
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umode_t mode;
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int acc_mode;
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int intent;
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int lookup_flags;
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};
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extern struct file *do_filp_open(int dfd, struct filename *pathname,
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const struct open_flags *op);
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extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
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const char *, const struct open_flags *);
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extern long do_handle_open(int mountdirfd,
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struct file_handle __user *ufh, int open_flag);
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extern int open_check_o_direct(struct file *f);
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/*
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* inode.c
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*/
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extern spinlock_t inode_sb_list_lock;
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extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);
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extern void inode_add_lru(struct inode *inode);
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/*
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* fs-writeback.c
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*/
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extern void inode_wb_list_del(struct inode *inode);
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extern long 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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/*
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* dcache.c
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*/
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extern struct dentry *__d_alloc(struct super_block *, const struct qstr *);
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extern int d_set_mounted(struct dentry *dentry);
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extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
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/*
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* read_write.c
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*/
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extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
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/*
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* pipe.c
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*/
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extern const struct file_operations pipefifo_fops;
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/*
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* fs_pin.c
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*/
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extern void group_pin_kill(struct hlist_head *p);
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extern void mnt_pin_kill(struct mount *m);
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/*
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* fs/nsfs.c
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*/
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extern struct dentry_operations ns_dentry_operations;
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