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![NeilBrown](/assets/img/avatar_default.png)
md/raid allows metadata management to be performed in user-space. A various times, particularly on device failure, the metadata needs to be updated before further writes can be permitted. This means that the user-space program which updates metadata much not block on writeout, and so must not allocate memory. mlockall(MCL_CURRENT|MCL_FUTURE) and pre-allocation can avoid all memory allocation issues for user-memory, but that does not help kernel memory. Several kernel objects can be pre-allocated. e.g. files opened before any writes to the array are permitted. However some kernel allocation happens in places that cannot be pre-allocated. In particular, writes to sysfs files (to tell md that it can now allow writes to the array) allocate a buffer using GFP_KERNEL. This patch allows attributes to be marked as "PREALLOC". In that case the maximal buffer is allocated when the file is opened, and then used on each write instead of allocating a new buffer. As the same buffer is now shared for all writes on the same file description, the mutex is extended to cover full use of the buffer including the copy_from_user(). The new __ATTR_PREALLOC() 'or's a new flag in to the 'mode', which is inspected by sysfs_add_file_mode_ns() to determine if the file should be marked as requiring prealloc. Despite the comment, we *do* use ->seq_show together with ->prealloc in this patch. The next patch fixes that. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
480 lines
13 KiB
C
480 lines
13 KiB
C
/*
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* sysfs.h - definitions for the device driver filesystem
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*
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* Copyright (c) 2001,2002 Patrick Mochel
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* Copyright (c) 2004 Silicon Graphics, Inc.
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#ifndef _SYSFS_H_
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#define _SYSFS_H_
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#include <linux/kernfs.h>
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/list.h>
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#include <linux/lockdep.h>
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#include <linux/kobject_ns.h>
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#include <linux/stat.h>
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#include <linux/atomic.h>
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struct kobject;
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struct module;
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struct bin_attribute;
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enum kobj_ns_type;
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struct attribute {
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const char *name;
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umode_t mode;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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bool ignore_lockdep:1;
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struct lock_class_key *key;
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struct lock_class_key skey;
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#endif
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};
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/**
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* sysfs_attr_init - initialize a dynamically allocated sysfs attribute
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* @attr: struct attribute to initialize
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*
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* Initialize a dynamically allocated struct attribute so we can
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* make lockdep happy. This is a new requirement for attributes
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* and initially this is only needed when lockdep is enabled.
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* Lockdep gives a nice error when your attribute is added to
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* sysfs if you don't have this.
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*/
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define sysfs_attr_init(attr) \
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do { \
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static struct lock_class_key __key; \
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\
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(attr)->key = &__key; \
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} while (0)
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#else
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#define sysfs_attr_init(attr) do {} while (0)
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#endif
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struct attribute_group {
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const char *name;
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umode_t (*is_visible)(struct kobject *,
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struct attribute *, int);
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struct attribute **attrs;
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struct bin_attribute **bin_attrs;
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};
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/**
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* Use these macros to make defining attributes easier. See include/linux/device.h
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* for examples..
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*/
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#define SYSFS_PREALLOC 010000
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#define __ATTR(_name, _mode, _show, _store) { \
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.attr = {.name = __stringify(_name), \
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.mode = VERIFY_OCTAL_PERMISSIONS(_mode) }, \
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.show = _show, \
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.store = _store, \
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}
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#define __ATTR_PREALLOC(_name, _mode, _show, _store) { \
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.attr = {.name = __stringify(_name), \
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.mode = SYSFS_PREALLOC | VERIFY_OCTAL_PERMISSIONS(_mode) },\
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.show = _show, \
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.store = _store, \
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}
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#define __ATTR_RO(_name) { \
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.attr = { .name = __stringify(_name), .mode = S_IRUGO }, \
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.show = _name##_show, \
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}
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#define __ATTR_WO(_name) { \
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.attr = { .name = __stringify(_name), .mode = S_IWUSR }, \
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.store = _name##_store, \
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}
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#define __ATTR_RW(_name) __ATTR(_name, (S_IWUSR | S_IRUGO), \
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_name##_show, _name##_store)
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#define __ATTR_NULL { .attr = { .name = NULL } }
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) { \
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.attr = {.name = __stringify(_name), .mode = _mode, \
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.ignore_lockdep = true }, \
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.show = _show, \
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.store = _store, \
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}
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#else
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#define __ATTR_IGNORE_LOCKDEP __ATTR
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#endif
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#define __ATTRIBUTE_GROUPS(_name) \
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static const struct attribute_group *_name##_groups[] = { \
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&_name##_group, \
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NULL, \
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}
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#define ATTRIBUTE_GROUPS(_name) \
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static const struct attribute_group _name##_group = { \
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.attrs = _name##_attrs, \
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}; \
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__ATTRIBUTE_GROUPS(_name)
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struct file;
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struct vm_area_struct;
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struct bin_attribute {
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struct attribute attr;
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size_t size;
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void *private;
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ssize_t (*read)(struct file *, struct kobject *, struct bin_attribute *,
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char *, loff_t, size_t);
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ssize_t (*write)(struct file *, struct kobject *, struct bin_attribute *,
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char *, loff_t, size_t);
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int (*mmap)(struct file *, struct kobject *, struct bin_attribute *attr,
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struct vm_area_struct *vma);
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};
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/**
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* sysfs_bin_attr_init - initialize a dynamically allocated bin_attribute
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* @attr: struct bin_attribute to initialize
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*
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* Initialize a dynamically allocated struct bin_attribute so we
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* can make lockdep happy. This is a new requirement for
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* attributes and initially this is only needed when lockdep is
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* enabled. Lockdep gives a nice error when your attribute is
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* added to sysfs if you don't have this.
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*/
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#define sysfs_bin_attr_init(bin_attr) sysfs_attr_init(&(bin_attr)->attr)
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/* macros to create static binary attributes easier */
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#define __BIN_ATTR(_name, _mode, _read, _write, _size) { \
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.attr = { .name = __stringify(_name), .mode = _mode }, \
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.read = _read, \
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.write = _write, \
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.size = _size, \
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}
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#define __BIN_ATTR_RO(_name, _size) { \
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.attr = { .name = __stringify(_name), .mode = S_IRUGO }, \
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.read = _name##_read, \
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.size = _size, \
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}
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#define __BIN_ATTR_RW(_name, _size) __BIN_ATTR(_name, \
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(S_IWUSR | S_IRUGO), _name##_read, \
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_name##_write, _size)
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#define __BIN_ATTR_NULL __ATTR_NULL
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#define BIN_ATTR(_name, _mode, _read, _write, _size) \
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struct bin_attribute bin_attr_##_name = __BIN_ATTR(_name, _mode, _read, \
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_write, _size)
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#define BIN_ATTR_RO(_name, _size) \
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struct bin_attribute bin_attr_##_name = __BIN_ATTR_RO(_name, _size)
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#define BIN_ATTR_RW(_name, _size) \
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struct bin_attribute bin_attr_##_name = __BIN_ATTR_RW(_name, _size)
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struct sysfs_ops {
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ssize_t (*show)(struct kobject *, struct attribute *, char *);
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ssize_t (*store)(struct kobject *, struct attribute *, const char *, size_t);
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};
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#ifdef CONFIG_SYSFS
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int __must_check sysfs_create_dir_ns(struct kobject *kobj, const void *ns);
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void sysfs_remove_dir(struct kobject *kobj);
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int __must_check sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
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const void *new_ns);
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int __must_check sysfs_move_dir_ns(struct kobject *kobj,
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struct kobject *new_parent_kobj,
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const void *new_ns);
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int __must_check sysfs_create_file_ns(struct kobject *kobj,
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const struct attribute *attr,
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const void *ns);
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int __must_check sysfs_create_files(struct kobject *kobj,
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const struct attribute **attr);
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int __must_check sysfs_chmod_file(struct kobject *kobj,
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const struct attribute *attr, umode_t mode);
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void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
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const void *ns);
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bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr);
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void sysfs_remove_files(struct kobject *kobj, const struct attribute **attr);
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int __must_check sysfs_create_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr);
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void sysfs_remove_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr);
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int __must_check sysfs_create_link(struct kobject *kobj, struct kobject *target,
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const char *name);
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int __must_check sysfs_create_link_nowarn(struct kobject *kobj,
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struct kobject *target,
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const char *name);
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void sysfs_remove_link(struct kobject *kobj, const char *name);
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int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
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const char *old_name, const char *new_name,
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const void *new_ns);
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void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
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const char *name);
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int __must_check sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp);
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int __must_check sysfs_create_groups(struct kobject *kobj,
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const struct attribute_group **groups);
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int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_remove_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_remove_groups(struct kobject *kobj,
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const struct attribute_group **groups);
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int sysfs_add_file_to_group(struct kobject *kobj,
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const struct attribute *attr, const char *group);
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void sysfs_remove_file_from_group(struct kobject *kobj,
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const struct attribute *attr, const char *group);
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int sysfs_merge_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_unmerge_group(struct kobject *kobj,
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const struct attribute_group *grp);
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int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
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struct kobject *target, const char *link_name);
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void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
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const char *link_name);
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void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
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int __must_check sysfs_init(void);
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static inline void sysfs_enable_ns(struct kernfs_node *kn)
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{
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return kernfs_enable_ns(kn);
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}
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#else /* CONFIG_SYSFS */
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static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
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{
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return 0;
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}
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static inline void sysfs_remove_dir(struct kobject *kobj)
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{
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}
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static inline int sysfs_rename_dir_ns(struct kobject *kobj,
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const char *new_name, const void *new_ns)
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{
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return 0;
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}
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static inline int sysfs_move_dir_ns(struct kobject *kobj,
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struct kobject *new_parent_kobj,
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const void *new_ns)
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{
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return 0;
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}
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static inline int sysfs_create_file_ns(struct kobject *kobj,
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const struct attribute *attr,
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const void *ns)
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{
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return 0;
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}
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static inline int sysfs_create_files(struct kobject *kobj,
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const struct attribute **attr)
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{
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return 0;
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}
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static inline int sysfs_chmod_file(struct kobject *kobj,
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const struct attribute *attr, umode_t mode)
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{
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return 0;
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}
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static inline void sysfs_remove_file_ns(struct kobject *kobj,
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const struct attribute *attr,
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const void *ns)
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{
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}
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static inline bool sysfs_remove_file_self(struct kobject *kobj,
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const struct attribute *attr)
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{
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return false;
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}
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static inline void sysfs_remove_files(struct kobject *kobj,
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const struct attribute **attr)
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{
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}
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static inline int sysfs_create_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr)
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{
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return 0;
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}
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static inline void sysfs_remove_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr)
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{
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}
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static inline int sysfs_create_link(struct kobject *kobj,
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struct kobject *target, const char *name)
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{
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return 0;
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}
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static inline int sysfs_create_link_nowarn(struct kobject *kobj,
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struct kobject *target,
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const char *name)
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{
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return 0;
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}
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static inline void sysfs_remove_link(struct kobject *kobj, const char *name)
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{
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}
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static inline int sysfs_rename_link_ns(struct kobject *k, struct kobject *t,
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const char *old_name,
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const char *new_name, const void *ns)
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{
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return 0;
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}
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static inline void sysfs_delete_link(struct kobject *k, struct kobject *t,
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const char *name)
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{
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}
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static inline int sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline int sysfs_create_groups(struct kobject *kobj,
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const struct attribute_group **groups)
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{
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return 0;
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}
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static inline int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline void sysfs_remove_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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}
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static inline void sysfs_remove_groups(struct kobject *kobj,
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const struct attribute_group **groups)
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{
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}
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static inline int sysfs_add_file_to_group(struct kobject *kobj,
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const struct attribute *attr, const char *group)
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{
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return 0;
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}
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static inline void sysfs_remove_file_from_group(struct kobject *kobj,
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const struct attribute *attr, const char *group)
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{
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}
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static inline int sysfs_merge_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline void sysfs_unmerge_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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}
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static inline int sysfs_add_link_to_group(struct kobject *kobj,
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const char *group_name, struct kobject *target,
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const char *link_name)
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{
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return 0;
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}
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static inline void sysfs_remove_link_from_group(struct kobject *kobj,
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const char *group_name, const char *link_name)
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{
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}
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static inline void sysfs_notify(struct kobject *kobj, const char *dir,
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const char *attr)
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{
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}
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static inline int __must_check sysfs_init(void)
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{
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return 0;
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}
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static inline void sysfs_enable_ns(struct kernfs_node *kn)
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{
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}
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#endif /* CONFIG_SYSFS */
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static inline int __must_check sysfs_create_file(struct kobject *kobj,
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const struct attribute *attr)
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{
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return sysfs_create_file_ns(kobj, attr, NULL);
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}
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static inline void sysfs_remove_file(struct kobject *kobj,
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const struct attribute *attr)
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{
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sysfs_remove_file_ns(kobj, attr, NULL);
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}
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static inline int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
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const char *old_name, const char *new_name)
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{
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return sysfs_rename_link_ns(kobj, target, old_name, new_name, NULL);
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}
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static inline void sysfs_notify_dirent(struct kernfs_node *kn)
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{
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kernfs_notify(kn);
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}
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static inline struct kernfs_node *sysfs_get_dirent(struct kernfs_node *parent,
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const unsigned char *name)
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{
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return kernfs_find_and_get(parent, name);
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}
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static inline struct kernfs_node *sysfs_get(struct kernfs_node *kn)
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{
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kernfs_get(kn);
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return kn;
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}
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static inline void sysfs_put(struct kernfs_node *kn)
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{
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kernfs_put(kn);
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}
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#endif /* _SYSFS_H_ */
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