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c28cc36469
Use a seqlock in the fs_struct to enable us to take an atomic copy of the complete cwd and root paths. Use this in the RCU lookup path to avoid a thread-shared spinlock in RCU lookup operations. Multi-threaded apps may now perform path lookups with scalability matching multi-process apps. Operations such as stat(2) become very scalable for multi-threaded workload. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
#ifndef _LINUX_FS_STRUCT_H
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#define _LINUX_FS_STRUCT_H
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#include <linux/path.h>
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#include <linux/spinlock.h>
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#include <linux/seqlock.h>
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struct fs_struct {
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int users;
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spinlock_t lock;
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seqcount_t seq;
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int umask;
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int in_exec;
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struct path root, pwd;
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};
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extern struct kmem_cache *fs_cachep;
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extern void exit_fs(struct task_struct *);
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extern void set_fs_root(struct fs_struct *, struct path *);
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extern void set_fs_pwd(struct fs_struct *, struct path *);
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extern struct fs_struct *copy_fs_struct(struct fs_struct *);
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extern void free_fs_struct(struct fs_struct *);
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extern void daemonize_fs_struct(void);
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extern int unshare_fs_struct(void);
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static inline void get_fs_root(struct fs_struct *fs, struct path *root)
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{
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spin_lock(&fs->lock);
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*root = fs->root;
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path_get(root);
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spin_unlock(&fs->lock);
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}
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static inline void get_fs_pwd(struct fs_struct *fs, struct path *pwd)
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{
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spin_lock(&fs->lock);
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*pwd = fs->pwd;
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path_get(pwd);
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spin_unlock(&fs->lock);
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}
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static inline void get_fs_root_and_pwd(struct fs_struct *fs, struct path *root,
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struct path *pwd)
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{
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spin_lock(&fs->lock);
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*root = fs->root;
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path_get(root);
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*pwd = fs->pwd;
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path_get(pwd);
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spin_unlock(&fs->lock);
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}
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#endif /* _LINUX_FS_STRUCT_H */
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