sysfs: Support sysfs_notify from atomic context with new sysfs_notify_dirent
Support sysfs_notify from atomic context with new sysfs_notify_dirent
sysfs_notify currently takes sysfs_mutex.
This means that it cannot be called in atomic context.
sysfs_mutex is sometimes held over a malloc (sysfs_rename_dir)
so it can block on low memory.
In md I want to be able to notify on a sysfs attribute from
atomic context, and I don't want to block on low memory because I
could be in the writeout path for freeing memory.
So:
- export the "sysfs_dirent" structure along with sysfs_get, sysfs_put
and sysfs_get_dirent so I can get the sysfs_dirent that I want to
notify on and hold it in an md structure.
- split sysfs_notify_dirent out of sysfs_notify so the sysfs_dirent
can be notified on with no blocking (just a spinlock).
Signed-off-by: Neil Brown <neilb@suse.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 8ec406a..d8e0230 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -78,6 +78,8 @@
ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t);
};
+struct sysfs_dirent;
+
#ifdef CONFIG_SYSFS
int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
@@ -118,10 +120,13 @@
const struct attribute *attr, const char *group);
void sysfs_notify(struct kobject *kobj, char *dir, char *attr);
-
+void sysfs_notify_dirent(struct sysfs_dirent *sd);
+struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+ const unsigned char *name);
+struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
+void sysfs_put(struct sysfs_dirent *sd);
void sysfs_printk_last_file(void);
-
-extern int __must_check sysfs_init(void);
+int __must_check sysfs_init(void);
#else /* CONFIG_SYSFS */
@@ -227,6 +232,22 @@
static inline void sysfs_notify(struct kobject *kobj, char *dir, char *attr)
{
}
+static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
+{
+}
+static inline
+struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+ const unsigned char *name)
+{
+ return NULL;
+}
+static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
+{
+ return NULL;
+}
+static inline void sysfs_put(struct sysfs_dirent *sd)
+{
+}
static inline int __must_check sysfs_init(void)
{