proc: remove m_cache_vma

Instead of setting m->version in the show method, set it in m_next(),
where it should be.  Also remove the fallback code for failing to find a
vma, or version being zero.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200317193201.9924-2-adobriyan@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 4b19a46..981085b 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -131,21 +131,14 @@ m_next_vma(struct proc_maps_private *priv, struct vm_area_struct *vma)
        return vma->vm_next ?: priv->tail_vma;
 }
 
-static void m_cache_vma(struct seq_file *m, struct vm_area_struct *vma)
-{
-       if (m->count < m->size) /* vma is copied successfully */
-               m->version = m_next_vma(m->private, vma) ? vma->vm_end : -1UL;
-}
-
 static void *m_start(struct seq_file *m, loff_t *ppos)
 {
        struct proc_maps_private *priv = m->private;
        unsigned long last_addr = m->version;
        struct mm_struct *mm;
        struct vm_area_struct *vma;
-       unsigned int pos = *ppos;
 
-       /* See m_cache_vma(). Zero at the start or after lseek. */
+       /* See m_next(). Zero at the start or after lseek. */
        if (last_addr == -1UL)
                return NULL;
 
@@ -170,28 +163,11 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
        hold_task_mempolicy(priv);
        priv->tail_vma = get_gate_vma(mm);
 
-       if (last_addr) {
-               vma = find_vma(mm, last_addr - 1);
-               if (vma && vma->vm_start <= last_addr)
-                       vma = m_next_vma(priv, vma);
-               if (vma)
-                       return vma;
-       }
-
-       m->version = 0;
-       if (pos < mm->map_count) {
-               for (vma = mm->mmap; pos; pos--) {
-                       m->version = vma->vm_start;
-                       vma = vma->vm_next;
-               }
+       vma = find_vma(mm, last_addr);
+       if (vma)
                return vma;
-       }
-
-       /* we do not bother to update m->version in this case */
-       if (pos == mm->map_count && priv->tail_vma)
-               return priv->tail_vma;
 
-       return NULL;
+       return priv->tail_vma;
 }
 
 static void *m_next(struct seq_file *m, void *v, loff_t *pos)
@@ -201,6 +177,8 @@ static void *m_next(struct seq_file *m, void *v, loff_t *pos)
 
        (*pos)++;
        next = m_next_vma(priv, v);
+       m->version = next ? next->vm_start : -1UL;
+
        return next;
 }
 
@@ -359,7 +337,6 @@ done:
 static int show_map(struct seq_file *m, void *v)
 {
        show_map_vma(m, v);
-       m_cache_vma(m, v);
        return 0;
 }
 
@@ -843,8 +820,6 @@ static int show_smap(struct seq_file *m, void *v)
                seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
        show_smap_vma_flags(m, vma);
 
-       m_cache_vma(m, vma);
-
        return 0;
 }
 
@@ -1883,7 +1858,6 @@ static int show_numa_map(struct seq_file *m, void *v)
        seq_printf(m, " kernelpagesize_kB=%lu", vma_kernel_pagesize(vma) >> 10);
 out:
        seq_putc(m, '\n');
-       m_cache_vma(m, vma);
        return 0;
 }