[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>

9 files changed, 205 insertions, 8 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 5c704d05627a..8157f2e2d515 100644
--- a/fs/Kconfig
+++ b/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
diff --git a/fs/ext2/Makefile b/fs/ext2/Makefile
index ee240a14e70f..c5d02da73bc3 100644
--- a/fs/ext2/Makefile
+++ b/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
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 8f0fd726c3f1..eed521d22cf0 100644
--- a/fs/ext2/ext2.h
+++ b/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 */
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index f5e86141ec54..2b3d572365af 100644
--- a/fs/ext2/file.c
+++ b/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
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index a50d9db4b6e4..53dceb0c6593 100644
--- a/fs/ext2/inode.c
+++ b/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;
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 3176b3d3ffa8..c5513953c825 100644
--- a/fs/ext2/namei.c
+++ b/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);
         }
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 661c3d98d946..876e391f2871 100644
--- a/fs/ext2/super.c
+++ b/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) {
diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
new file mode 100644
index 000000000000..d44431d1a338
--- /dev/null
+++ b/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);
+}
diff --git a/fs/ext2/xip.h b/fs/ext2/xip.h
new file mode 100644
index 000000000000..aa85331d6c56
--- /dev/null
+++ b/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