[PATCH] Automatic file-max sizing

The default for NR_FILES of 8192 is far too low for many workloads. This
patch does dynamic sizing for it instead. It assumes file+inode+dentry
are roughly 1K and will use upto 10% of the memory for it.

Also removes two obsolete prototypes.

fs/dcache.c

@@ -1283,6 +1283,7 @@ void __init vfs_caches_init(unsigned long mempages)
 
 	dcache_init(mempages);
 	inode_init(mempages);
+	files_init(mempages); 
 	mnt_init(mempages);
 	bdev_cache_init();
 	cdev_cache_init();

fs/file_table.c

@@ -186,3 +186,17 @@ int fs_may_remount_ro(struct super_block *sb)
 	file_list_unlock();
 	return 0;
 }
+
+void __init files_init(unsigned long mempages)
+{ 
+	int n; 
+	/* One file with associated inode and dcache is very roughly 1K. 
+	 * Per default don't use more than 10% of our memory for files. 
+	 */ 
+
+	n = (mempages * (PAGE_SIZE / 1024)) / 10;
+	files_stat.max_files = n; 
+	if (files_stat.max_files < NR_FILE)
+		files_stat.max_files = NR_FILE;
+} 
+

include/linux/fs.h

@@ -208,6 +208,7 @@ extern void update_atime (struct inode *);
 extern void buffer_init(unsigned long);
 extern void inode_init(unsigned long);
 extern void mnt_init(unsigned long);
+extern void files_init(unsigned long);
 
 /* bh state bits */
 enum bh_state_bits {
@@ -1492,8 +1493,6 @@ static inline int is_mounted(kdev_t dev)
 	}
 	return 0;
 }
-unsigned long generate_cluster(kdev_t, int b[], int);
-unsigned long generate_cluster_swab32(kdev_t, int b[], int);
 extern kdev_t ROOT_DEV;
 extern char root_device_name[];