1 files changed, 14 insertions, 8 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 6529226..3b8b739 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -548,12 +548,12 @@ static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry,
 	struct inode *inode = dentry->d_inode;
 	struct shmem_inode_info *info = SHMEM_I(inode);
 
-	spin_lock(&info->lock);
-	shmem_recalc_inode(inode);
-	spin_unlock(&info->lock);
-
+	if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
+		spin_lock(&info->lock);
+		shmem_recalc_inode(inode);
+		spin_unlock(&info->lock);
+	}
 	generic_fillattr(inode, stat);
-
 	return 0;
 }
 
@@ -586,10 +586,16 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 		}
 		if (newsize <= oldsize) {
 			loff_t holebegin = round_up(newsize, PAGE_SIZE);
-			unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
-			shmem_truncate_range(inode, newsize, (loff_t)-1);
+			if (oldsize > holebegin)
+				unmap_mapping_range(inode->i_mapping,
+							holebegin, 0, 1);
+			if (info->alloced)
+				shmem_truncate_range(inode,
+							newsize, (loff_t)-1);
 			/* unmap again to remove racily COWed private pages */
-			unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
+			if (oldsize > holebegin)
+				unmap_mapping_range(inode->i_mapping,
+							holebegin, 0, 1);
 		}
 	}