f6acf8bb6a
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
121 lines
3.3 KiB
C
121 lines
3.3 KiB
C
/*
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* kernfs.h - pseudo filesystem decoupled from vfs locking
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*
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* This file is released under the GPLv2.
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*/
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#ifndef __LINUX_KERNFS_H
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#define __LINUX_KERNFS_H
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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struct file;
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struct iattr;
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struct seq_file;
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struct vm_area_struct;
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struct sysfs_dirent;
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struct sysfs_open_file {
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/* published fields */
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struct sysfs_dirent *sd;
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struct file *file;
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/* private fields, do not use outside kernfs proper */
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struct mutex mutex;
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int event;
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struct list_head list;
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bool mmapped;
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const struct vm_operations_struct *vm_ops;
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};
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struct kernfs_ops {
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/*
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* Read is handled by either seq_file or raw_read().
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*
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* If seq_show() is present, seq_file path is active. The behavior
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* is equivalent to single_open(). @sf->private points to the
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* associated sysfs_open_file.
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*
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* read() is bounced through kernel buffer and a read larger than
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* PAGE_SIZE results in partial operation of PAGE_SIZE.
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*/
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int (*seq_show)(struct seq_file *sf, void *v);
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ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes,
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loff_t off);
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/*
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* write() is bounced through kernel buffer and a write larger than
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* PAGE_SIZE results in partial operation of PAGE_SIZE.
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*/
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ssize_t (*write)(struct sysfs_open_file *of, char *buf, size_t bytes,
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loff_t off);
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int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);
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};
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#ifdef CONFIG_SYSFS
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struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,
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const char *name, void *priv,
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const void *ns);
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struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
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const char *name,
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struct sysfs_dirent *target);
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void kernfs_remove(struct sysfs_dirent *sd);
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int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
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const void *ns);
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int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent,
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const char *new_name, const void *new_ns);
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void kernfs_enable_ns(struct sysfs_dirent *sd);
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int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr);
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#else /* CONFIG_SYSFS */
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static inline struct sysfs_dirent *
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kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv,
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const void *ns)
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{ return ERR_PTR(-ENOSYS); }
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static inline struct sysfs_dirent *
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kernfs_create_link(struct sysfs_dirent *parent, const char *name,
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struct sysfs_dirent *target)
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{ return ERR_PTR(-ENOSYS); }
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static inline void kernfs_remove(struct sysfs_dirent *sd) { }
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static inline int kernfs_remove_by_name_ns(struct sysfs_dirent *parent,
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const char *name, const void *ns)
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{ return -ENOSYS; }
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static inline int kernfs_rename_ns(struct sysfs_dirent *sd,
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struct sysfs_dirent *new_parent,
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const char *new_name, const void *new_ns)
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{ return -ENOSYS; }
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static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { }
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static inline int kernfs_setattr(struct sysfs_dirent *sd,
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const struct iattr *iattr)
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{ return -ENOSYS; }
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#endif /* CONFIG_SYSFS */
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static inline struct sysfs_dirent *
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kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv)
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{
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return kernfs_create_dir_ns(parent, name, priv, NULL);
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}
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static inline int kernfs_remove_by_name(struct sysfs_dirent *parent,
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const char *name)
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{
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return kernfs_remove_by_name_ns(parent, name, NULL);
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}
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#endif /* __LINUX_KERNFS_H */
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