proc: move pagecount stuff to fs/proc/page.c

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

1 files changed, 147 insertions, 0 deletions

diff --git a/fs/proc/page.c b/fs/proc/page.c
new file mode 100644
index 00000000000..767d95a6d1b
--- /dev/null
+++ b/fs/proc/page.c
@@ -0,0 +1,147 @@
+#include <linux/bootmem.h>
+#include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+#define KPMSIZE sizeof(u64)
+#define KPMMASK (KPMSIZE - 1)
+/* /proc/kpagecount - an array exposing page counts
+ *
+ * Each entry is a u64 representing the corresponding
+ * physical page count.
+ */
+static ssize_t kpagecount_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 pcount;
+
+	pfn = src / KPMSIZE;
+	count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
+	if (src & KPMMASK || count & KPMMASK)
+		return -EINVAL;
+
+	while (count > 0) {
+		ppage = NULL;
+		if (pfn_valid(pfn))
+			ppage = pfn_to_page(pfn);
+		pfn++;
+		if (!ppage)
+			pcount = 0;
+		else
+			pcount = page_mapcount(ppage);
+
+		if (put_user(pcount, out++)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		count -= KPMSIZE;
+	}
+
+	*ppos += (char __user *)out - buf;
+	if (!ret)
+		ret = (char __user *)out - buf;
+	return ret;
+}
+
+static const struct file_operations proc_kpagecount_operations = {
+	.llseek = mem_lseek,
+	.read = kpagecount_read,
+};
+
+/* /proc/kpageflags - an array exposing page flags
+ *
+ * Each entry is a u64 representing the corresponding
+ * physical page flags.
+ */
+
+/* These macros are used to decouple internal flags from exported ones */
+
+#define KPF_LOCKED     0
+#define KPF_ERROR      1
+#define KPF_REFERENCED 2
+#define KPF_UPTODATE   3
+#define KPF_DIRTY      4
+#define KPF_LRU        5
+#define KPF_ACTIVE     6
+#define KPF_SLAB       7
+#define KPF_WRITEBACK  8
+#define KPF_RECLAIM    9
+#define KPF_BUDDY     10
+
+#define kpf_copy_bit(flags, srcpos, dstpos) (((flags >> srcpos) & 1) << dstpos)
+
+static ssize_t kpageflags_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 kflags, uflags;
+
+	pfn = src / KPMSIZE;
+	count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
+	if (src & KPMMASK || count & KPMMASK)
+		return -EINVAL;
+
+	while (count > 0) {
+		ppage = NULL;
+		if (pfn_valid(pfn))
+			ppage = pfn_to_page(pfn);
+		pfn++;
+		if (!ppage)
+			kflags = 0;
+		else
+			kflags = ppage->flags;
+
+		uflags = kpf_copy_bit(KPF_LOCKED, PG_locked, kflags) |
+			kpf_copy_bit(kflags, KPF_ERROR, PG_error) |
+			kpf_copy_bit(kflags, KPF_REFERENCED, PG_referenced) |
+			kpf_copy_bit(kflags, KPF_UPTODATE, PG_uptodate) |
+			kpf_copy_bit(kflags, KPF_DIRTY, PG_dirty) |
+			kpf_copy_bit(kflags, KPF_LRU, PG_lru) |
+			kpf_copy_bit(kflags, KPF_ACTIVE, PG_active) |
+			kpf_copy_bit(kflags, KPF_SLAB, PG_slab) |
+			kpf_copy_bit(kflags, KPF_WRITEBACK, PG_writeback) |
+			kpf_copy_bit(kflags, KPF_RECLAIM, PG_reclaim) |
+			kpf_copy_bit(kflags, KPF_BUDDY, PG_buddy);
+
+		if (put_user(uflags, out++)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		count -= KPMSIZE;
+	}
+
+	*ppos += (char __user *)out - buf;
+	if (!ret)
+		ret = (char __user *)out - buf;
+	return ret;
+}
+
+static const struct file_operations proc_kpageflags_operations = {
+	.llseek = mem_lseek,
+	.read = kpageflags_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);
+	return 0;
+}
+module_init(proc_page_init);