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-rw-r--r--fs/sysfs/file.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 81e3f727833f..e2fafc0a9b36 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -47,7 +47,6 @@ struct sysfs_buffer {
char *page;
const struct sysfs_ops *ops;
struct mutex mutex;
- int needs_read_fill;
int event;
struct list_head list;
};
@@ -95,12 +94,10 @@ static int fill_read_buffer(struct dentry *dentry, struct sysfs_buffer *buffer)
/* Try to struggle along */
count = PAGE_SIZE - 1;
}
- if (count >= 0) {
- buffer->needs_read_fill = 0;
+ if (count >= 0)
buffer->count = count;
- } else {
+ else
ret = count;
- }
return ret;
}
@@ -130,7 +127,11 @@ sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
ssize_t retval = 0;
mutex_lock(&buffer->mutex);
- if (buffer->needs_read_fill || *ppos == 0) {
+ /*
+ * Fill on zero offset and the first read so that silly things like
+ * "dd bs=1 skip=N" can work on sysfs files.
+ */
+ if (*ppos == 0 || !buffer->page) {
retval = fill_read_buffer(file->f_path.dentry, buffer);
if (retval)
goto out;
@@ -166,14 +167,15 @@ static int fill_write_buffer(struct sysfs_buffer *buffer,
if (count >= PAGE_SIZE)
count = PAGE_SIZE - 1;
error = copy_from_user(buffer->page, buf, count);
- buffer->needs_read_fill = 1;
- /* if buf is assumed to contain a string, terminate it by \0,
- so e.g. sscanf() can scan the string easily */
+
+ /*
+ * If buf is assumed to contain a string, terminate it by \0, so
+ * e.g. sscanf() can scan the string easily.
+ */
buffer->page[count] = 0;
return error ? -EFAULT : count;
}
-
/**
* flush_write_buffer - push buffer to kobject.
* @dentry: dentry to the attribute
@@ -368,7 +370,6 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
goto err_out;
mutex_init(&buffer->mutex);
- buffer->needs_read_fill = 1;
buffer->ops = ops;
file->private_data = buffer;
@@ -435,7 +436,6 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
return DEFAULT_POLLMASK;
trigger:
- buffer->needs_read_fill = 1;
return DEFAULT_POLLMASK|POLLERR|POLLPRI;
}