[PATCH] tmpfs 3/5 pretend dirent size

[Hugh Dickins]

2.4.20-pre6 had mod by hpa, to make tmpfs directory size always 1
instead of always 0, so as not to mislead apps.  Okay, but I think
it looks better if we use a pretend directory entry size instead.

--- tmpfs2/mm/shmem.c	Sat Sep 14 18:21:23 2002
+++ tmpfs3/mm/shmem.c	Sat Sep 14 18:21:23 2002
@@ -35,6 +35,9 @@
 
 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
 
+/* Pretend that each entry is of this size in directory's i_size */
+#define BOGO_DIRENT_SIZE 20
+
 #define SHMEM_SB(sb) (&sb->u.shmem_sb)
 
 static struct super_operations shmem_ops;
@@ -737,7 +740,7 @@
 		case S_IFDIR:
 			inode->i_nlink++;
 			/* Some things misbehave if size == 0 on a directory */
-			inode->i_size = 1;
+			inode->i_size = 2 * BOGO_DIRENT_SIZE;
 			inode->i_op = &shmem_dir_inode_operations;
 			inode->i_fop = &dcache_dir_ops;
 			break;
@@ -1024,6 +1027,7 @@
 	int error = -ENOSPC;
 
 	if (inode) {
+		dir->i_size += BOGO_DIRENT_SIZE;
 		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 		d_instantiate(dentry, inode);
 		dget(dentry); /* Extra count - pin the dentry in core */
@@ -1057,6 +1061,7 @@
 	if (S_ISDIR(inode->i_mode))
 		return -EPERM;
 
+	dir->i_size += BOGO_DIRENT_SIZE;
 	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 	inode->i_nlink++;
 	atomic_inc(&inode->i_count);	/* New dentry reference */
@@ -1101,6 +1106,8 @@
 static int shmem_unlink(struct inode * dir, struct dentry *dentry)
 {
 	struct inode *inode = dentry->d_inode;
+
+	dir->i_size -= BOGO_DIRENT_SIZE;
 	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 	inode->i_nlink--;
 	dput(dentry);	/* Undo the count from "create" - this does all the work */
@@ -1139,6 +1146,8 @@
 		new_dir->i_nlink++;
 	}
 
+	old_dir->i_size -= BOGO_DIRENT_SIZE;
+	new_dir->i_size += BOGO_DIRENT_SIZE;
 	old_dir->i_ctime = old_dir->i_mtime =
 	new_dir->i_ctime = new_dir->i_mtime =
 	inode->i_ctime = CURRENT_TIME;
@@ -1187,6 +1196,7 @@
 		page_cache_release(page);
 		up(&info->sem);
 	}
+	dir->i_size += BOGO_DIRENT_SIZE;
 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 	d_instantiate(dentry, inode);
 	dget(dentry);