[v2,1/5] cramfs: direct memory access support

diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig
index 11b29d491b..5eed4ad2d5 100644
--- a/fs/cramfs/Kconfig
+++ b/fs/cramfs/Kconfig
@@ -1,6 +1,5 @@ 
 config CRAMFS
 	tristate "Compressed ROM file system support (cramfs) (OBSOLETE)"
-	depends on BLOCK
 	select ZLIB_INFLATE
 	help
 	  Saying Y here includes support for CramFs (Compressed ROM File
@@ -20,3 +19,32 @@  config CRAMFS
 	  in terms of performance and features.
 
 	  If unsure, say N.
+
+config CRAMFS_BLOCKDEV
+	bool "Support CramFs image over a regular block device" if EXPERT
+	depends on CRAMFS && BLOCK
+	default y
+	help
+	  This option allows the CramFs driver to load data from a regular
+	  block device such a disk partition or a ramdisk.
+	  
+config CRAMFS_PHYSMEM
+	bool "Support CramFs image directly mapped in physical memory"
+	depends on CRAMFS
+	default y if !CRAMFS_BLOCKDEV
+	help
+	  This option allows the CramFs driver to load data directly from
+	  a linear adressed memory range (usually non volatile memory
+	  like flash) instead of going through the block device layer.
+	  This saves some memory since no intermediate buffering is
+	  necessary.
+
+	  The filesystem type for this feature is "cramfs_physmem".
+	  The location of the CramFs image in memory is board
+	  dependent. Therefore, if you say Y, you must know the proper
+	  physical address where to store the CramFs image and specify
+	  it using the physaddr=0x******** mount option (for example:
+	  "mount -t cramfs_physmem -o physaddr=0x100000 none /mnt").
+
+	  If unsure, say N.
+
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index 7919967488..393eb27ef4 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -24,6 +24,7 @@ 
 #include <linux/mutex.h>
 #include <uapi/linux/cramfs_fs.h>
 #include <linux/uaccess.h>
+#include <linux/io.h>
 
 #include "internal.h"
 
@@ -36,6 +37,8 @@  struct cramfs_sb_info {
 	unsigned long blocks;
 	unsigned long files;
 	unsigned long flags;
+	void *linear_virt_addr;
+	phys_addr_t linear_phys_addr;
 };
 
 static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
@@ -140,6 +143,9 @@  static struct inode *get_cramfs_inode(struct super_block *sb,
  * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
  * worry about end-of-buffer issues even when decompressing a full
  * page cache.
+ *
+ * Note: This is all optimized away at compile time when
+ *       CONFIG_CRAMFS_BLOCKDEV=n.
  */
 #define READ_BUFFERS (2)
 /* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
@@ -160,10 +166,10 @@  static struct super_block *buffer_dev[READ_BUFFERS];
 static int next_buffer;
 
 /*
- * Returns a pointer to a buffer containing at least LEN bytes of
- * filesystem starting at byte offset OFFSET into the filesystem.
+ * Populate our block cache and return a pointer from it.
  */
-static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
+static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
+				unsigned int len)
 {
 	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
 	struct page *pages[BLKS_PER_BUF];
@@ -239,7 +245,39 @@  static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i
 	return read_buffers[buffer] + offset;
 }
 
-static void cramfs_kill_sb(struct super_block *sb)
+/*
+ * Return a pointer to the linearly addressed cramfs image in memory.
+ */
+static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
+				unsigned int len)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+	if (!len)
+		return NULL;
+	if (len > sbi->size || offset > sbi->size - len)
+	       return page_address(ZERO_PAGE(0));	
+	return sbi->linear_virt_addr + offset;
+}
+
+/*
+ * Returns a pointer to a buffer containing at least LEN bytes of
+ * filesystem starting at byte offset OFFSET into the filesystem.
+ */
+static void *cramfs_read(struct super_block *sb, unsigned int offset,
+			 unsigned int len)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+	if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM) && sbi->linear_virt_addr)
+		return cramfs_direct_read(sb, offset, len);
+	else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+		return cramfs_blkdev_read(sb, offset, len);
+	else
+		return NULL;
+}
+
+static void cramfs_blkdev_kill_sb(struct super_block *sb)
 {
 	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
 
@@ -247,6 +285,16 @@  static void cramfs_kill_sb(struct super_block *sb)
 	kfree(sbi);
 }
 
+static void cramfs_physmem_kill_sb(struct super_block *sb)
+{
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+	if (sbi->linear_virt_addr)
+		memunmap(sbi->linear_virt_addr);
+	kill_anon_super(sb);
+	kfree(sbi);
+}
+
 static int cramfs_remount(struct super_block *sb, int *flags, char *data)
 {
 	sync_filesystem(sb);
@@ -254,34 +302,24 @@  static int cramfs_remount(struct super_block *sb, int *flags, char *data)
 	return 0;
 }
 
-static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
+static int cramfs_read_super(struct super_block *sb,
+			     struct cramfs_super *super, int silent)
 {
-	int i;
-	struct cramfs_super super;
+	struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
 	unsigned long root_offset;
-	struct cramfs_sb_info *sbi;
-	struct inode *root;
-
-	sb->s_flags |= MS_RDONLY;
-
-	sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
-	if (!sbi)
-		return -ENOMEM;
-	sb->s_fs_info = sbi;
 
-	/* Invalidate the read buffers on mount: think disk change.. */
-	mutex_lock(&read_mutex);
-	for (i = 0; i < READ_BUFFERS; i++)
-		buffer_blocknr[i] = -1;
+	/* We don't know the real size yet */
+	sbi->size = PAGE_SIZE;
 
 	/* Read the first block and get the superblock from it */
-	memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
+	mutex_lock(&read_mutex);
+	memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
 	mutex_unlock(&read_mutex);
 
 	/* Do sanity checks on the superblock */
-	if (super.magic != CRAMFS_MAGIC) {
+	if (super->magic != CRAMFS_MAGIC) {
 		/* check for wrong endianness */
-		if (super.magic == CRAMFS_MAGIC_WEND) {
+		if (super->magic == CRAMFS_MAGIC_WEND) {
 			if (!silent)
 				pr_err("wrong endianness\n");
 			return -EINVAL;
@@ -289,10 +327,10 @@  static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
 
 		/* check at 512 byte offset */
 		mutex_lock(&read_mutex);
-		memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
+		memcpy(super, cramfs_read(sb, 512, sizeof(*super)), sizeof(*super));
 		mutex_unlock(&read_mutex);
-		if (super.magic != CRAMFS_MAGIC) {
-			if (super.magic == CRAMFS_MAGIC_WEND && !silent)
+		if (super->magic != CRAMFS_MAGIC) {
+			if (super->magic == CRAMFS_MAGIC_WEND && !silent)
 				pr_err("wrong endianness\n");
 			else if (!silent)
 				pr_err("wrong magic\n");
@@ -301,34 +339,34 @@  static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	/* get feature flags first */
-	if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
+	if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
 		pr_err("unsupported filesystem features\n");
 		return -EINVAL;
 	}
 
 	/* Check that the root inode is in a sane state */
-	if (!S_ISDIR(super.root.mode)) {
+	if (!S_ISDIR(super->root.mode)) {
 		pr_err("root is not a directory\n");
 		return -EINVAL;
 	}
 	/* correct strange, hard-coded permissions of mkcramfs */
-	super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
+	super->root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
 
-	root_offset = super.root.offset << 2;
-	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
-		sbi->size = super.size;
-		sbi->blocks = super.fsid.blocks;
-		sbi->files = super.fsid.files;
+	root_offset = super->root.offset << 2;
+	if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
+		sbi->size = super->size;
+		sbi->blocks = super->fsid.blocks;
+		sbi->files = super->fsid.files;
 	} else {
 		sbi->size = 1<<28;
 		sbi->blocks = 0;
 		sbi->files = 0;
 	}
-	sbi->magic = super.magic;
-	sbi->flags = super.flags;
+	sbi->magic = super->magic;
+	sbi->flags = super->flags;
 	if (root_offset == 0)
 		pr_info("empty filesystem");
-	else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
+	else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
 		 ((root_offset != sizeof(struct cramfs_super)) &&
 		  (root_offset != 512 + sizeof(struct cramfs_super))))
 	{
@@ -336,9 +374,18 @@  static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
 		return -EINVAL;
 	}
 
+	return 0;
+}
+
+static int cramfs_finalize_super(struct super_block *sb,
+				 struct cramfs_inode *cramfs_root)
+{
+	struct inode *root;
+
 	/* Set it all up.. */
+	sb->s_flags |= MS_RDONLY;
 	sb->s_op = &cramfs_ops;
-	root = get_cramfs_inode(sb, &super.root, 0);
+	root = get_cramfs_inode(sb, cramfs_root, 0);
 	if (IS_ERR(root))
 		return PTR_ERR(root);
 	sb->s_root = d_make_root(root);
@@ -347,6 +394,92 @@  static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
 	return 0;
 }
 
+static int cramfs_blkdev_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct cramfs_sb_info *sbi;
+	struct cramfs_super super;
+	int i, err;
+
+	sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
+	sb->s_fs_info = sbi;
+
+	/* Invalidate the read buffers on mount: think disk change.. */
+	for (i = 0; i < READ_BUFFERS; i++)
+		buffer_blocknr[i] = -1;
+
+	err = cramfs_read_super(sb, &super, silent);
+	if (err)
+		return err;
+	return cramfs_finalize_super(sb, &super.root);
+}
+
+static int cramfs_physmem_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct cramfs_sb_info *sbi;
+	struct cramfs_super super;
+	char *p;
+	int err;
+
+	sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
+	if (!sbi)
+		return -ENOMEM;
+	sb->s_fs_info = sbi;
+
+	/*
+	 * The physical location of the cramfs image is specified as
+	 * a mount parameter.  This parameter is mandatory for obvious
+	 * reasons.  Some validation is made on the phys address but this
+	 * is not exhaustive and we count on the fact that someone using
+	 * this feature is supposed to know what he/she's doing.
+	 */
+	if (!data || !(p = strstr((char *)data, "physaddr="))) {
+		pr_err("unknown physical address for linear cramfs image\n");
+		return -EINVAL;
+	}
+	sbi->linear_phys_addr = memparse(p + 9, NULL);
+	if (!sbi->linear_phys_addr) {
+		pr_err("bad value for cramfs image physical address\n");
+		return -EINVAL;
+	}
+	if (sbi->linear_phys_addr & (PAGE_SIZE-1)) {
+		pr_err("physical address %pap for linear cramfs isn't aligned to a page boundary\n",
+			&sbi->linear_phys_addr);
+		return -EINVAL;
+	}
+
+	/*
+	 * Map only one page for now.  Will remap it when fs size is known.
+	 * Although we'll only read from it, we want the CPU cache to
+	 * kick in for the higher throughput it provides, hence MEMREMAP_WB.
+	 */
+	pr_info("checking physical address %pap for linear cramfs image\n", &sbi->linear_phys_addr);
+	sbi->linear_virt_addr = memremap(sbi->linear_phys_addr, PAGE_SIZE,
+					 MEMREMAP_WB);
+	if (!sbi->linear_virt_addr) {
+		pr_err("ioremap of the linear cramfs image failed\n");
+		return -ENOMEM;
+	}
+
+	err = cramfs_read_super(sb, &super, silent);
+	if (err)
+		return err;
+
+	/* Remap the whole filesystem now */
+	pr_info("linear cramfs image appears to be %lu KB in size\n",
+		sbi->size/1024);
+	memunmap(sbi->linear_virt_addr);
+	sbi->linear_virt_addr = memremap(sbi->linear_phys_addr, sbi->size,
+					 MEMREMAP_WB);
+	if (!sbi->linear_virt_addr) {
+		pr_err("ioremap of the linear cramfs image failed\n");
+		return -ENOMEM;
+	}
+
+	return cramfs_finalize_super(sb, &super.root);
+}
+
 static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
@@ -573,38 +706,67 @@  static const struct super_operations cramfs_ops = {
 	.statfs		= cramfs_statfs,
 };
 
-static struct dentry *cramfs_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data)
+static struct dentry *cramfs_blkdev_mount(struct file_system_type *fs_type,
+				int flags, const char *dev_name, void *data)
+{
+	return mount_bdev(fs_type, flags, dev_name, data, cramfs_blkdev_fill_super);
+}
+
+static struct dentry *cramfs_physmem_mount(struct file_system_type *fs_type,
+				int flags, const char *dev_name, void *data)
 {
-	return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
+	return mount_nodev(fs_type, flags, data, cramfs_physmem_fill_super);
 }
 
 static struct file_system_type cramfs_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "cramfs",
-	.mount		= cramfs_mount,
-	.kill_sb	= cramfs_kill_sb,
+	.mount		= cramfs_blkdev_mount,
+	.kill_sb	= cramfs_blkdev_kill_sb,
 	.fs_flags	= FS_REQUIRES_DEV,
 };
+
+static struct file_system_type cramfs_physmem_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "cramfs_physmem",
+	.mount		= cramfs_physmem_mount,
+	.kill_sb	= cramfs_physmem_kill_sb,
+};
+
+#ifdef CONFIG_CRAMFS_BLOCKDEV
 MODULE_ALIAS_FS("cramfs");
+#endif
+#ifdef CONFIG_CRAMFS_PHYSMEM
+MODULE_ALIAS_FS("cramfs_physmem");
+#endif
 
 static int __init init_cramfs_fs(void)
 {
 	int rv;
 
-	rv = cramfs_uncompress_init();
-	if (rv < 0)
-		return rv;
-	rv = register_filesystem(&cramfs_fs_type);
-	if (rv < 0)
-		cramfs_uncompress_exit();
-	return rv;
+	if ((rv = cramfs_uncompress_init()) < 0)
+		goto err0;
+	if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) &&
+	    (rv = register_filesystem(&cramfs_fs_type)) < 0)
+		goto err1;
+	if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM) &&
+	    (rv = register_filesystem(&cramfs_physmem_fs_type)) < 0)
+		goto err2;
+	return 0;
+
+err2:	if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+		unregister_filesystem(&cramfs_fs_type);
+err1:	cramfs_uncompress_exit();
+err0:	return rv;
 }
 
 static void __exit exit_cramfs_fs(void)
 {
 	cramfs_uncompress_exit();
-	unregister_filesystem(&cramfs_fs_type);
+	if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+		unregister_filesystem(&cramfs_fs_type);
+	if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM))
+		unregister_filesystem(&cramfs_physmem_fs_type);
 }
 
 module_init(init_cramfs_fs)