/proc/pid/maps: don't show pgoff of pure ANON VMAs

Recently, it's argued that what proc/pid/maps shows is ugly when a 32bit
binary runs on 64bit host.

/proc/pid/maps outputs vma's pgoff member but vma->pgoff is of no use
information is the vma is for ANON.  With this patch, /proc/pid/maps shows
just 0 if no file backing store.

[akpm@linux-foundation.org: coding-style fixes]
[kamezawa.hiroyu@jp.fujitsu.com: coding-style fixes]
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mike Waychison <mikew@google.com>
Reported-by: NYing Han <yinghan@google.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

@@ -204,6 +204,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 	struct file *file = vma->vm_file;
 	int flags = vma->vm_flags;
 	unsigned long ino = 0;
+	unsigned long long pgoff = 0;
 	dev_t dev = 0;
 	int len;
 
@@ -211,6 +212,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 		struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 		dev = inode->i_sb->s_dev;
 		ino = inode->i_ino;
+		pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
 	}
 
 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
@@ -220,7 +222,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 			flags & VM_WRITE ? 'w' : '-',
 			flags & VM_EXEC ? 'x' : '-',
 			flags & VM_MAYSHARE ? 's' : 'p',
-			((loff_t)vma->vm_pgoff) << PAGE_SHIFT,
+			pgoff,
 			MAJOR(dev), MINOR(dev), ino, &len);
 
 	/*

fs/proc/task_nommu.c

@@ -126,6 +126,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 	struct file *file;
 	dev_t dev = 0;
 	int flags, len;
+	unsigned long long pgoff = 0;
 
 	flags = vma->vm_flags;
 	file = vma->vm_file;
@@ -134,6 +135,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 		struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 		dev = inode->i_sb->s_dev;
 		ino = inode->i_ino;
+		pgoff = (loff_t)vma->pg_off << PAGE_SHIFT;
 	}
 
 	seq_printf(m,
@@ -144,7 +146,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 		   flags & VM_WRITE ? 'w' : '-',
 		   flags & VM_EXEC ? 'x' : '-',
 		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
-		   (unsigned long long) vma->vm_pgoff << PAGE_SHIFT,
+		   pgoff,
 		   MAJOR(dev), MINOR(dev), ino, &len);
 
 	if (file) {