[PATCH] xip: ext2: execute in place

These are the ext2 related parts.  Ext2 now uses the xip_* file operations
along with the get_xip_page aop when mounted with -o xip.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/Kconfig

@@ -50,6 +50,23 @@ config EXT2_FS_SECURITY
 	  If you are not using a security module that requires using
 	  extended attributes for file security labels, say N.
 
+config EXT2_FS_XIP
+	bool "Ext2 execute in place support"
+	depends on EXT2_FS
+	help
+	  Execute in place can be used on memory-backed block devices. If you
+	  enable this option, you can select to mount block devices which are
+	  capable of this feature without using the page cache.
+
+	  If you do not use a block device that is capable of using this,
+	  or if unsure, say N.
+
+config FS_XIP
+# execute in place
+	bool
+	depends on EXT2_FS_XIP
+	default y
+
 config EXT3_FS
 	tristate "Ext3 journalling file system support"
 	help

fs/ext2/Makefile

@@ -10,3 +10,4 @@ ext2-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
 ext2-$(CONFIG_EXT2_FS_XATTR)	 += xattr.o xattr_user.o xattr_trusted.o
 ext2-$(CONFIG_EXT2_FS_POSIX_ACL) += acl.o
 ext2-$(CONFIG_EXT2_FS_SECURITY)	 += xattr_security.o
+ext2-$(CONFIG_EXT2_FS_XIP)	 += xip.o

fs/ext2/ext2.h

@@ -147,9 +147,11 @@ extern struct file_operations ext2_dir_operations;
 /* file.c */
 extern struct inode_operations ext2_file_inode_operations;
 extern struct file_operations ext2_file_operations;
+extern struct file_operations ext2_xip_file_operations;
 
 /* inode.c */
 extern struct address_space_operations ext2_aops;
+extern struct address_space_operations ext2_aops_xip;
 extern struct address_space_operations ext2_nobh_aops;
 
 /* namei.c */

fs/ext2/file.c

@@ -55,6 +55,24 @@ struct file_operations ext2_file_operations = {
 	.sendfile	= generic_file_sendfile,
 };
 
+#ifdef CONFIG_EXT2_FS_XIP
+struct file_operations ext2_xip_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= do_sync_read,
+	.write		= do_sync_write,
+	.aio_read	= xip_file_aio_read,
+	.aio_write	= xip_file_aio_write,
+	.ioctl		= ext2_ioctl,
+	.mmap		= xip_file_mmap,
+	.open		= generic_file_open,
+	.release	= ext2_release_file,
+	.fsync		= ext2_sync_file,
+	.readv		= xip_file_readv,
+	.writev		= xip_file_writev,
+	.sendfile	= xip_file_sendfile,
+};
+#endif
+
 struct inode_operations ext2_file_inode_operations = {
 	.truncate	= ext2_truncate,
 #ifdef CONFIG_EXT2_FS_XATTR

fs/ext2/inode.c

@@ -33,6 +33,7 @@
 #include <linux/mpage.h>
 #include "ext2.h"
 #include "acl.h"
+#include "xip.h"
 
 MODULE_AUTHOR("Remy Card and others");
 MODULE_DESCRIPTION("Second Extended Filesystem");
@@ -594,6 +595,16 @@ out:
 	if (err)
 		goto cleanup;
 
+	if (ext2_use_xip(inode->i_sb)) {
+		/*
+		 * we need to clear the block
+		 */
+		err = ext2_clear_xip_target (inode,
+			le32_to_cpu(chain[depth-1].key));
+		if (err)
+			goto cleanup;
+	}
+
 	if (ext2_splice_branch(inode, iblock, chain, partial, left) < 0)
 		goto changed;
 
@@ -691,6 +702,11 @@ struct address_space_operations ext2_aops = {
 	.writepages		= ext2_writepages,
 };
 
+struct address_space_operations ext2_aops_xip = {
+	.bmap			= ext2_bmap,
+	.get_xip_page		= ext2_get_xip_page,
+};
+
 struct address_space_operations ext2_nobh_aops = {
 	.readpage		= ext2_readpage,
 	.readpages		= ext2_readpages,
@@ -910,7 +926,9 @@ void ext2_truncate (struct inode * inode)
 	iblock = (inode->i_size + blocksize-1)
 					>> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
 
-	if (test_opt(inode->i_sb, NOBH))
+	if (mapping_is_xip(inode->i_mapping))
+		xip_truncate_page(inode->i_mapping, inode->i_size);
+	else if (test_opt(inode->i_sb, NOBH))
 		nobh_truncate_page(inode->i_mapping, inode->i_size);
 	else
 		block_truncate_page(inode->i_mapping,
@@ -1110,11 +1128,16 @@ void ext2_read_inode (struct inode * inode)
 
 	if (S_ISREG(inode->i_mode)) {
 		inode->i_op = &ext2_file_inode_operations;
-		inode->i_fop = &ext2_file_operations;
-		if (test_opt(inode->i_sb, NOBH))
+		if (ext2_use_xip(inode->i_sb)) {
+			inode->i_mapping->a_ops = &ext2_aops_xip;
+			inode->i_fop = &ext2_xip_file_operations;
+		} else if (test_opt(inode->i_sb, NOBH)) {
 			inode->i_mapping->a_ops = &ext2_nobh_aops;
-		else
+			inode->i_fop = &ext2_file_operations;
+		} else {
 			inode->i_mapping->a_ops = &ext2_aops;
+			inode->i_fop = &ext2_file_operations;
+		}
 	} else if (S_ISDIR(inode->i_mode)) {
 		inode->i_op = &ext2_dir_inode_operations;
 		inode->i_fop = &ext2_dir_operations;

fs/ext2/namei.c

@@ -34,6 +34,7 @@
 #include "ext2.h"
 #include "xattr.h"
 #include "acl.h"
+#include "xip.h"
 
 /*
  * Couple of helper functions - make the code slightly cleaner.
@@ -127,11 +128,16 @@ static int ext2_create (struct inode * dir, struct dentry * dentry, int mode, st
 	int err = PTR_ERR(inode);
 	if (!IS_ERR(inode)) {
 		inode->i_op = &ext2_file_inode_operations;
-		inode->i_fop = &ext2_file_operations;
-		if (test_opt(inode->i_sb, NOBH))
+		if (ext2_use_xip(inode->i_sb)) {
+			inode->i_mapping->a_ops = &ext2_aops_xip;
+			inode->i_fop = &ext2_xip_file_operations;
+		} else if (test_opt(inode->i_sb, NOBH)) {
 			inode->i_mapping->a_ops = &ext2_nobh_aops;
-		else
+			inode->i_fop = &ext2_file_operations;
+		} else {
 			inode->i_mapping->a_ops = &ext2_aops;
+			inode->i_fop = &ext2_file_operations;
+		}
 		mark_inode_dirty(inode);
 		err = ext2_add_nondir(dentry, inode);
 	}

fs/ext2/super.c

@@ -31,6 +31,7 @@
 #include "ext2.h"
 #include "xattr.h"
 #include "acl.h"
+#include "xip.h"
 
 static void ext2_sync_super(struct super_block *sb,
 			    struct ext2_super_block *es);
@@ -257,7 +258,7 @@ enum {
 	Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 	Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
 	Opt_nouid32, Opt_check, Opt_nocheck, Opt_debug, Opt_oldalloc, Opt_orlov, Opt_nobh,
-	Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
+	Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl, Opt_xip,
 	Opt_ignore, Opt_err,
 };
 
@@ -286,6 +287,7 @@ static match_table_t tokens = {
 	{Opt_nouser_xattr, "nouser_xattr"},
 	{Opt_acl, "acl"},
 	{Opt_noacl, "noacl"},
+	{Opt_xip, "xip"},
 	{Opt_ignore, "grpquota"},
 	{Opt_ignore, "noquota"},
 	{Opt_ignore, "quota"},
@@ -397,6 +399,13 @@ static int parse_options (char * options,
 			printk("EXT2 (no)acl options not supported\n");
 			break;
 #endif
+		case Opt_xip:
+#ifdef CONFIG_EXT2_FS_XIP
+			set_opt (sbi->s_mount_opt, XIP);
+#else
+			printk("EXT2 xip option not supported\n");
+#endif
+			break;
 		case Opt_ignore:
 			break;
 		default:
@@ -640,6 +649,9 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 		((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 		 MS_POSIXACL : 0);
 
+	ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
+				    EXT2_MOUNT_XIP if not */
+
 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 	    (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 	     EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
@@ -668,6 +680,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 
 	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 
+	if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
+				  (sb->s_blocksize != blocksize))) {
+		if (!silent)
+			printk("XIP: Unsupported blocksize\n");
+		goto failed_mount;
+	}
+
 	/* If the blocksize doesn't match, re-read the thing.. */
 	if (sb->s_blocksize != blocksize) {
 		brelse(bh);
@@ -916,6 +935,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
 {
 	struct ext2_sb_info * sbi = EXT2_SB(sb);
 	struct ext2_super_block * es;
+	unsigned long old_mount_opt = sbi->s_mount_opt;
 
 	/*
 	 * Allow the "check" option to be passed as a remount option.
@@ -927,6 +947,11 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
 		((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
 
 	es = sbi->s_es;
+	if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
+	    (old_mount_opt & EXT2_MOUNT_XIP)) &&
+	    invalidate_inodes(sb))
+		ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
+			     "xip remain in cache (no functional problem)");
 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 		return 0;
 	if (*flags & MS_RDONLY) {

fs/ext2/xip.c

@@ -0,0 +1,80 @@
+/*
+ *  linux/fs/ext2/xip.c
+ *
+ * Copyright (C) 2005 IBM Corporation
+ * Author: Carsten Otte (cotte@de.ibm.com)
+ */
+
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/genhd.h>
+#include <linux/buffer_head.h>
+#include <linux/ext2_fs_sb.h>
+#include <linux/ext2_fs.h>
+#include "ext2.h"
+#include "xip.h"
+
+static inline int
+__inode_direct_access(struct inode *inode, sector_t sector, unsigned long *data) {
+	BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
+	return inode->i_sb->s_bdev->bd_disk->fops
+		->direct_access(inode->i_sb->s_bdev,sector,data);
+}
+
+int
+ext2_clear_xip_target(struct inode *inode, int block) {
+	sector_t sector = block*(PAGE_SIZE/512);
+	unsigned long data;
+	int rc;
+
+	rc = __inode_direct_access(inode, sector, &data);
+	if (rc)
+		return rc;
+	clear_page((void*)data);
+	return 0;
+}
+
+void ext2_xip_verify_sb(struct super_block *sb)
+{
+	struct ext2_sb_info *sbi = EXT2_SB(sb);
+
+	if ((sbi->s_mount_opt & EXT2_MOUNT_XIP)) {
+		if ((sb->s_bdev == NULL) ||
+			sb->s_bdev->bd_disk == NULL ||
+			sb->s_bdev->bd_disk->fops == NULL ||
+			sb->s_bdev->bd_disk->fops->direct_access == NULL) {
+			sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
+			ext2_warning(sb, __FUNCTION__,
+				"ignoring xip option - not supported by bdev");
+		}
+	}
+}
+
+struct page*
+ext2_get_xip_page(struct address_space *mapping, sector_t blockno,
+		   int create)
+{
+	int rc;
+	unsigned long data;
+	struct buffer_head tmp;
+
+	tmp.b_state = 0;
+	tmp.b_blocknr = 0;
+	rc = ext2_get_block(mapping->host, blockno/(PAGE_SIZE/512) , &tmp,
+				create);
+	if (rc)
+		return ERR_PTR(rc);
+	if (tmp.b_blocknr == 0) {
+		/* SPARSE block */
+		BUG_ON(create);
+		return ERR_PTR(-ENODATA);
+	}
+
+	rc = __inode_direct_access
+		(mapping->host,tmp.b_blocknr*(PAGE_SIZE/512) ,&data);
+	if (rc)
+		return ERR_PTR(rc);
+
+	SetPageUptodate(virt_to_page(data));
+	return virt_to_page(data);
+}

fs/ext2/xip.h

@@ -0,0 +1,25 @@
+/*
+ *  linux/fs/ext2/xip.h
+ *
+ * Copyright (C) 2005 IBM Corporation
+ * Author: Carsten Otte (cotte@de.ibm.com)
+ */
+
+#ifdef CONFIG_EXT2_FS_XIP
+extern void ext2_xip_verify_sb (struct super_block *);
+extern int ext2_clear_xip_target (struct inode *, int);
+
+static inline int ext2_use_xip (struct super_block *sb)
+{
+	struct ext2_sb_info *sbi = EXT2_SB(sb);
+	return (sbi->s_mount_opt & EXT2_MOUNT_XIP);
+}
+struct page* ext2_get_xip_page (struct address_space *, sector_t, int);
+#define mapping_is_xip(map) unlikely(map->a_ops->get_xip_page)
+#else
+#define mapping_is_xip(map)			0
+#define ext2_xip_verify_sb(sb)			do { } while (0)
+#define ext2_use_xip(sb)			0
+#define ext2_clear_xip_target(inode, chain)	0
+#define ext2_get_xip_page			NULL
+#endif