page-types: make standalone pagemap/kpageflags read routines

Refactor the code to be more modular and easier to reuse.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 89 insertions, 65 deletions

diff --git a/Documentation/vm/page-types.c b/Documentation/vm/page-types.c
index 6bdcc0632c24..18e891a329e0 100644
--- a/Documentation/vm/page-types.c
+++ b/Documentation/vm/page-types.c
@@ -161,8 +161,6 @@ static unsigned long	pg_start[MAX_VMAS];
 static unsigned long    pg_end[MAX_VMAS];
 static unsigned long    voffset;
 
-static int              pagemap_fd;
-
 #define MAX_BIT_FILTERS 64
 static int              nr_bit_filters;
 static uint64_t         opt_mask[MAX_BIT_FILTERS];
@@ -170,7 +168,7 @@ static uint64_t		opt_bits[MAX_BIT_FILTERS];
 
 static int              page_size;
 
-#define PAGES_BATCH     (64 << 10)      /* 64k pages */
+static int              pagemap_fd;
 static int              kpageflags_fd;
 
 #define HASH_SHIFT      13
@@ -226,6 +224,62 @@ int checked_open(const char *pathname, int flags)
         return fd;
 }
 
+/*
+ * pagemap/kpageflags routines
+ */
+
+static unsigned long do_u64_read(int fd, char *name,
+                                 uint64_t *buf,
+                                 unsigned long index,
+                                 unsigned long count)
+{
+        long bytes;
+
+        if (index > ULONG_MAX / 8)
+                fatal("index overflow: %lu\n", index);
+
+        if (lseek(fd, index * 8, SEEK_SET) < 0) {
+                perror(name);
+                exit(EXIT_FAILURE);
+        }
+
+        bytes = read(fd, buf, count * 8);
+        if (bytes < 0) {
+                perror(name);
+                exit(EXIT_FAILURE);
+        }
+        if (bytes % 8)
+                fatal("partial read: %lu bytes\n", bytes);
+
+        return bytes / 8;
+}
+
+static unsigned long kpageflags_read(uint64_t *buf,
+                                     unsigned long index,
+                                     unsigned long pages)
+{
+        return do_u64_read(kpageflags_fd, PROC_KPAGEFLAGS, buf, index, pages);
+}
+
+static unsigned long pagemap_read(uint64_t *buf,
+                                  unsigned long index,
+                                  unsigned long pages)
+{
+        return do_u64_read(pagemap_fd, "/proc/pid/pagemap", buf, index, pages);
+}
+
+static unsigned long pagemap_pfn(uint64_t val)
+{
+        unsigned long pfn;
+
+        if (val & PM_PRESENT)
+                pfn = PM_PFRAME(val);
+        else
+                pfn = 0;
+
+        return pfn;
+}
+
 
 /*
  * page flag names
@@ -432,79 +486,53 @@ static void add_page(unsigned long offset, uint64_t flags)
         total_pages++;
 }
 
+#define KPAGEFLAGS_BATCH        (64 << 10)      /* 64k pages */
 static void walk_pfn(unsigned long index, unsigned long count)
 {
+        uint64_t buf[KPAGEFLAGS_BATCH];
         unsigned long batch;
-        unsigned long n;
+        unsigned long pages;
         unsigned long i;
 
-        if (index > ULONG_MAX / KPF_BYTES)
-                fatal("index overflow: %lu\n", index);
-
-        lseek(kpageflags_fd, index * KPF_BYTES, SEEK_SET);
-
         while (count) {
-                uint64_t kpageflags_buf[KPF_BYTES * PAGES_BATCH];
-
-                batch = min_t(unsigned long, count, PAGES_BATCH);
-                n = read(kpageflags_fd, kpageflags_buf, batch * KPF_BYTES);
-                if (n == 0)
+                batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH);
+                pages = kpageflags_read(buf, index, batch);
+                if (pages == 0)
                         break;
-                if (n < 0) {
-                        perror(PROC_KPAGEFLAGS);
-                        exit(EXIT_FAILURE);
-                }
-
-                if (n % KPF_BYTES != 0)
-                        fatal("partial read: %lu bytes\n", n);
-                n = n / KPF_BYTES;
 
-                for (i = 0; i < n; i++)
-                        add_page(index + i, kpageflags_buf[i]);
+                for (i = 0; i < pages; i++)
+                        add_page(index + i, buf[i]);
 
-                index += batch;
-                count -= batch;
+                index += pages;
+                count -= pages;
         }
 }
 
-
-#define PAGEMAP_BATCH   4096
-static unsigned long task_pfn(unsigned long pgoff)
+#define PAGEMAP_BATCH   (64 << 10)
+static void walk_vma(unsigned long index, unsigned long count)
 {
-        static uint64_t buf[PAGEMAP_BATCH];
-        static unsigned long start;
-        static long count;
-        uint64_t pfn;
+        uint64_t buf[PAGEMAP_BATCH];
+        unsigned long batch;
+        unsigned long pages;
+        unsigned long pfn;
+        unsigned long i;
 
-        if (pgoff < start || pgoff >= start + count) {
-                if (lseek64(pagemap_fd,
-                            (uint64_t)pgoff * PM_ENTRY_BYTES,
-                            SEEK_SET) < 0) {
-                        perror("pagemap seek");
-                        exit(EXIT_FAILURE);
-                }
-                count = read(pagemap_fd, buf, sizeof(buf));
-                if (count == 0)
-                        return 0;
-                if (count < 0) {
-                        perror("pagemap read");
-                        exit(EXIT_FAILURE);
-                }
-                if (count % PM_ENTRY_BYTES) {
-                        fatal("pagemap read not aligned.\n");
-                        exit(EXIT_FAILURE);
-                }
-                count /= PM_ENTRY_BYTES;
-                start = pgoff;
-        }
+        while (count) {
+                batch = min_t(unsigned long, count, PAGEMAP_BATCH);
+                pages = pagemap_read(buf, index, batch);
+                if (pages == 0)
+                        break;
 
-        pfn = buf[pgoff - start];
-        if (pfn & PM_PRESENT)
-                pfn = PM_PFRAME(pfn);
-        else
-                pfn = 0;
+                for (i = 0; i < pages; i++) {
+                        pfn = pagemap_pfn(buf[i]);
+                        voffset = index + i;
+                        if (pfn)
+                                walk_pfn(pfn, 1);
+                }
 
-        return pfn;
+                index += pages;
+                count -= pages;
+        }
 }
 
 static void walk_task(unsigned long index, unsigned long count)
@@ -524,11 +552,7 @@ static void walk_task(unsigned long index, unsigned long count)
                 index   = min_t(unsigned long, pg_end[i], end);
 
                 assert(voffset < index);
-                for (; voffset < index; voffset++) {
-                        unsigned long pfn = task_pfn(voffset);
-                        if (pfn)
-                                walk_pfn(pfn, 1);
-                }
+                walk_vma(voffset, index - voffset);
         }
 }