add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/fs/libfs.c
..
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@@ -955,8 +955,8 @@
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 EXPORT_SYMBOL_GPL(simple_attr_read);
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 /* interpret the buffer as a number to call the set function with */
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-ssize_t simple_attr_write(struct file *file, const char __user *buf,
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-			  size_t len, loff_t *ppos)
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+static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf,
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+			  size_t len, loff_t *ppos, bool is_signed)
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 {
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 	struct simple_attr *attr;
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 	unsigned long long val;
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@@ -977,7 +977,10 @@
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 		goto out;
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 	attr->set_buf[size] = '\0';
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-	ret = kstrtoull(attr->set_buf, 0, &val);
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+	if (is_signed)
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+		ret = kstrtoll(attr->set_buf, 0, &val);
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+	else
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+		ret = kstrtoull(attr->set_buf, 0, &val);
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 	if (ret)
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 		goto out;
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 	ret = attr->set(attr->data, val);
..
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@@ -987,8 +990,21 @@
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 	mutex_unlock(&attr->mutex);
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 	return ret;
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 }
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+
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+ssize_t simple_attr_write(struct file *file, const char __user *buf,
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+			  size_t len, loff_t *ppos)
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+{
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+	return simple_attr_write_xsigned(file, buf, len, ppos, false);
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+}
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 EXPORT_SYMBOL_GPL(simple_attr_write);
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+ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,
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+			  size_t len, loff_t *ppos)
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+{
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+	return simple_attr_write_xsigned(file, buf, len, ppos, true);
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+}
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+EXPORT_SYMBOL_GPL(simple_attr_write_signed);
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+
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 /**
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  * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
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  * @sb:		filesystem to do the file handle conversion on