Added the start of a standalone COW driver.

Cleaned up the code a bit to make it more separable.

6 files changed, 41 insertions, 9 deletions

diff --git a/arch/um/config_block.in b/arch/um/config_block.in
index 419bb71..18122a4 100644
--- a/arch/um/config_block.in
+++ b/arch/um/config_block.in
@@ -3,6 +3,12 @@ comment 'Block Devices'
 
 bool 'Virtual block device' CONFIG_BLK_DEV_UBD
 dep_bool '  Always do synchronous disk IO for UBD' CONFIG_BLK_DEV_UBD_SYNC $CONFIG_BLK_DEV_UBD
+bool 'COW device' CONFIG_COW
+
+if [ "$CONFIG_BLK_DEV_UBD" = "y" -o "$CONFIG_COW" = "y" ] ; then
+	define_bool CONFIG_COW_COMMON y
+fi
+
 tristate 'Loopback device support' CONFIG_BLK_DEV_LOOP
 dep_tristate 'Network block device support' CONFIG_BLK_DEV_NBD $CONFIG_NET
 tristate 'RAM disk support' CONFIG_BLK_DEV_RAM
diff --git a/arch/um/drivers/Makefile b/arch/um/drivers/Makefile
index 06f8a92..4b4b3aa 100644
--- a/arch/um/drivers/Makefile
+++ b/arch/um/drivers/Makefile
@@ -1,5 +1,5 @@
 # 
-# Copyright (C) 2000, 2002 Jeff Dike (jdike@karaya.com)
+# Copyright (C) 2000, 2002, 2003 Jeff Dike (jdike@karaya.com)
 # Licensed under the GPL
 #
 
@@ -18,7 +18,7 @@ pcap-objs := pcap_kern.o pcap_user.o -lpcap -L/usr/lib
 net-objs := net_kern.o net_user.o
 mconsole-objs := mconsole_kern.o mconsole_user.o
 hostaudio-objs := hostaudio_kern.o hostaudio_user.o
-ubd-objs := ubd_kern.o ubd_user.o cow_user.o
+ubd-objs := ubd_kern.o ubd_user.o
 port-objs := port_kern.o port_user.o
 harddog-objs := harddog_kern.o harddog_user.o
 
@@ -43,6 +43,8 @@ obj-$(CONFIG_PTY_CHAN) += pty.o
 obj-$(CONFIG_TTY_CHAN) += tty.o 
 obj-$(CONFIG_XTERM_CHAN) += xterm.o xterm_kern.o
 obj-$(CONFIG_UML_WATCHDOG) += harddog.o
+obj-$(CONFIG_COW) += cow_kern.o
+obj-$(CONFIG_COW_COMMON) += cow_user.o
 
 CFLAGS_pcap_user.o = -I/usr/include/pcap
 
diff --git a/arch/um/drivers/cow.h b/arch/um/drivers/cow.h
index e354d28..662ac5c 100644
--- a/arch/um/drivers/cow.h
+++ b/arch/um/drivers/cow.h
@@ -16,11 +16,17 @@
 extern int init_cow_file(int fd, char *cow_file, char *backing_file, 
 			 int sectorsize, int *bitmap_offset_out, 
 			 unsigned long *bitmap_len_out, int *data_offset_out);
-extern int read_cow_header(int fd, __u32 *magic_out, char **backing_file_out, 
-			   time_t *mtime_out, __u64 *size_out, 
-			   int *sectorsize_out, int *bitmap_offset_out);
+
+extern int file_reader(__u64 offset, char *buf, int len, void *arg);
+extern int read_cow_header(int (*reader)(__u64, char *, int, void *), 
+			   void *arg, __u32 *magic_out, 
+			   char **backing_file_out, time_t *mtime_out, 
+			   __u64 *size_out, int *sectorsize_out, 
+			   int *bitmap_offset_out);
+
 extern int write_cow_header(char *cow_file, int fd, char *backing_file, 
 			    int sectorsize, long long *size);
+
 extern void cow_sizes(__u64 size, int sectorsize, int bitmap_offset, 
 		      unsigned long *bitmap_len_out, int *data_offset_out);
 
diff --git a/arch/um/drivers/cow_user.c b/arch/um/drivers/cow_user.c
index d3ed767..675a716 100644
--- a/arch/um/drivers/cow_user.c
+++ b/arch/um/drivers/cow_user.c
@@ -165,7 +165,15 @@ int write_cow_header(char *cow_file, int fd, char *backing_file,
 	return(err);
 }
 
-int read_cow_header(int fd, __u32 *magic_out, char **backing_file_out, 
+int file_reader(__u64 offset, char *buf, int len, void *arg)
+{
+	int fd = *((int *) arg);
+
+	return(pread(fd, buf, len, offset));
+}
+
+int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg, 
+		    __u32 *magic_out, char **backing_file_out, 
 		    time_t *mtime_out, __u64 *size_out, 
 		    int *sectorsize_out, int *bitmap_offset_out)
 {
@@ -180,7 +188,7 @@ int read_cow_header(int fd, __u32 *magic_out, char **backing_file_out,
 		return(-ENOMEM);
 	}
 	err = -EINVAL;
-	n = read(fd, header, sizeof(*header));
+	n = (*reader)(0, (char *) header, sizeof(*header), arg);
 	if(n < offsetof(typeof(header->v1), backing_file)){
 		cow_printf("read_cow_header - short header\n");
 		goto out;
@@ -193,6 +201,7 @@ int read_cow_header(int fd, __u32 *magic_out, char **backing_file_out,
 	else if(magic == ntohl(COW_MAGIC)){
 		version = ntohl(header->v1.version);
 	}
+	/* No error printed because the non-COW case comes through here */
 	else goto out;
 
 	*magic_out = COW_MAGIC;
diff --git a/arch/um/drivers/ubd_user.c b/arch/um/drivers/ubd_user.c
index 81b8437..ba7d5b5 100644
--- a/arch/um/drivers/ubd_user.c
+++ b/arch/um/drivers/ubd_user.c
@@ -126,8 +126,8 @@ int open_ubd_file(char *file, struct openflags *openflags,
 	
 	if(backing_file_out == NULL) return(fd);
 
-	err = read_cow_header(fd, &magic, &backing_file, &mtime, &size, 
-			      &sectorsize, bitmap_offset_out);
+	err = read_cow_header(file_reader, &fd, &magic, &backing_file, &mtime, 
+			      &size, &sectorsize, bitmap_offset_out);
 	if(err && (*backing_file_out != NULL)){
 		printk("Failed to read COW header from COW file \"%s\", "
 		       "errno = %d\n", file, err);
diff --git a/include/linux/blk.h b/include/linux/blk.h
index f90d557..f16bcb4 100644
--- a/include/linux/blk.h
+++ b/include/linux/blk.h
@@ -329,6 +329,15 @@ static void floppy_off(unsigned int nr);
 #define DEVICE_ON(device)
 #define DEVICE_OFF(device)
 
+#elif (MAJOR_NR == COW_MAJOR)
+
+#define DEVICE_NAME "COW device"
+#define DEVICE_INTR do_cow
+#define DEVICE_REQUEST do_cow_request
+#define DEVICE_NR(device) (MINOR(device) >> COW_SHIFT)
+#define DEVICE_ON(device)
+#define DEVICE_OFF(device)
+
 #endif /* MAJOR_NR == whatever */
 
 /* provide DEVICE_xxx defaults, if not explicitly defined