[PATCH 2/3] proc: add /proc/kpagetype interface

[Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>]

From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: [PATCH] proc: add /proc/kpagetype interface

This makes page pageblock type information available to the user-space.

Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 fs/proc/page.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

Index: b/fs/proc/page.c
===================================================================
--- a/fs/proc/page.c	2012-05-31 16:30:49.215109568 +0200
+++ b/fs/proc/page.c	2012-05-31 16:30:50.559109495 +0200
@@ -254,11 +254,59 @@ static const struct file_operations proc
 	.read = kpageorder_read,
 };
 
+static ssize_t kpagetype_read(struct file *file, char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	u64 __user *out = (u64 __user *)buf;
+	struct page *ppage;
+	unsigned long src = *ppos;
+	unsigned long pfn;
+	ssize_t ret = 0;
+	u64 ptype;
+
+	pfn = src / KPMSIZE;
+	count = min_t(unsigned long, count,
+		      ((ARCH_PFN_OFFSET + max_pfn) * KPMSIZE) - src);
+	if (src & KPMMASK || count & KPMMASK)
+		return -EINVAL;
+
+	while (count > 0) {
+		if (pfn_valid(pfn))
+			ppage = pfn_to_page(pfn);
+		else
+			ppage = NULL;
+		if (!ppage)
+			ptype = 0;
+		else
+			ptype = get_pageblock_migratetype(ppage);
+
+		if (put_user(ptype, out)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		pfn++;
+		out++;
+		count -= KPMSIZE;
+	}
+
+	*ppos += (char __user *)out - buf;
+	if (!ret)
+		ret = (char __user *)out - buf;
+	return ret;
+}
+
+static const struct file_operations proc_kpagetype_operations = {
+	.llseek = mem_lseek,
+	.read = kpagetype_read,
+};
+
 static int __init proc_page_init(void)
 {
 	proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
 	proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
 	proc_create("kpageorder", S_IRUSR, NULL, &proc_kpageorder_operations);
+	proc_create("kpagetype", S_IRUSR, NULL, &proc_kpagetype_operations);
 	return 0;
 }
 module_init(proc_page_init);

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