patch-2.3.12 linux/drivers/char/raw.c

• Lines: 385
• Date: Mon Jul 26 22:50:35 1999
• Orig file: v2.3.11/linux/drivers/char/raw.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.11/linux/drivers/char/raw.c linux/drivers/char/raw.c
@@ -0,0 +1,384 @@
+/*
+ * linux/drivers/char/raw.c
+ *
+ * Front-end raw character devices.  These can be bound to any block
+ * devices to provide genuine Unix raw character device semantics.
+ *
+ * We reserve minor number 0 for a control interface.  ioctl()s on this
+ * device are used to bind the other minor numbers to block devices.
+ */
+
+#include <linux/fs.h>
+#include <linux/iobuf.h>
+#include <linux/major.h>
+#include <linux/blkdev.h>
+#include <linux/raw.h>
+#include <asm/uaccess.h>
+
+#define dprintk(x...) 
+
+static kdev_t raw_device_bindings[256] = {};
+static int raw_device_inuse[256] = {};
+static int raw_device_sector_size[256] = {};
+static int raw_device_sector_bits[256] = {};
+
+extern struct file_operations * get_blkfops(unsigned int major);
+
+static ssize_t rw_raw_dev(int rw, struct file *, char *, size_t, loff_t *);
+
+ssize_t	raw_read(struct file *, char *, size_t, loff_t *);
+ssize_t	raw_write(struct file *, const char *, size_t, loff_t *);
+int	raw_open(struct inode *, struct file *);
+int	raw_release(struct inode *, struct file *);
+int	raw_ctl_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
+
+
+static struct file_operations raw_fops = {
+	NULL,		/* llseek */
+	raw_read,	/* read */
+	raw_write,	/* write */
+	NULL,		/* readdir */
+	NULL,		/* poll */
+	NULL,		/* ioctl */
+	NULL,		/* mmap */
+	raw_open,	/* open */
+	NULL,		/* flush */
+	raw_release,	/* release */
+	NULL		/* fsync */
+};
+
+static struct file_operations raw_ctl_fops = {
+	NULL,		/* llseek */
+	NULL,		/* read */
+	NULL,		/* write */
+	NULL,		/* readdir */
+	NULL,		/* poll */
+	raw_ctl_ioctl,	/* ioctl */
+	NULL,		/* mmap */
+	raw_open,	/* open */
+	NULL,		/* flush */
+	NULL,		/* no special release code */
+	NULL		/* fsync */
+};
+
+
+
+void __init raw_init(void)
+{
+	register_chrdev(RAW_MAJOR, "raw", &raw_fops);
+}
+
+
+/*
+ * The raw IO open and release code needs to fake appropriate
+ * open/release calls to the underlying block devices.  
+ */
+
+static int bdev_open(kdev_t dev, int mode)
+{
+	int err = 0;
+	struct file dummy_file = {};
+	struct dentry dummy_dentry = {};
+	struct inode * inode = get_empty_inode();
+	
+	if (!inode)
+		return -ENOMEM;
+	
+	dummy_file.f_op = get_blkfops(MAJOR(dev));
+	if (!dummy_file.f_op) {
+		err = -ENODEV;
+		goto done;
+	}
+	
+	if (dummy_file.f_op->open) {
+		inode->i_rdev = dev;
+		dummy_dentry.d_inode = inode;
+		dummy_file.f_dentry = &dummy_dentry;
+		dummy_file.f_mode = mode;
+		err = dummy_file.f_op->open(inode, &dummy_file);
+	}
+
+ done:
+	iput(inode);
+	return err;
+}
+
+static int bdev_close(kdev_t dev)
+{
+	int err;
+	struct inode * inode = get_empty_inode();
+
+	if (!inode)
+		return -ENOMEM;
+	
+	inode->i_rdev = dev;
+	err = blkdev_release(inode);
+	iput(inode);
+	return err;
+}
+
+
+
+/* 
+ * Open/close code for raw IO.
+ */
+
+int raw_open(struct inode *inode, struct file *filp)
+{
+	int minor;
+	kdev_t bdev;
+	int err;
+	int sector_size;
+	int sector_bits;
+
+	minor = MINOR(inode->i_rdev);
+	
+	/* 
+	 * Is it the control device? 
+	 */
+	
+	if (minor == 0) {
+		filp->f_op = &raw_ctl_fops;
+		return 0;
+	}
+	
+	/*
+	 * No, it is a normal raw device.  All we need to do on open is
+	 * to check that the device is bound, and force the underlying
+	 * block device to a sector-size blocksize. 
+	 */
+
+	bdev = raw_device_bindings[minor];
+	if (bdev == NODEV) 
+		return -ENODEV;
+
+	err = bdev_open(bdev, filp->f_mode);
+	if (err)
+		return err;
+	
+	/*
+	 * Don't change the blocksize if we already have users using
+	 * this device 
+	 */
+
+	if (raw_device_inuse[minor]++)
+		return 0;
+	
+	/* 
+	 * Don't interfere with mounted devices: we cannot safely set
+	 * the blocksize on a device which is already mounted.  
+	 */
+	
+	sector_size = 512;
+	if (lookup_vfsmnt(bdev) != NULL) {
+		if (blksize_size[MAJOR(bdev)])
+			sector_size = blksize_size[MAJOR(bdev)][MINOR(bdev)];
+	} else {
+		if (hardsect_size[MAJOR(bdev)])
+			sector_size = hardsect_size[MAJOR(bdev)][MINOR(bdev)];
+	}
+
+	set_blocksize(bdev, sector_size);
+	raw_device_sector_size[minor] = sector_size;
+
+	for (sector_bits = 0; !(sector_size & 1); )
+		sector_size>>=1, sector_bits++;
+	raw_device_sector_bits[minor] = sector_bits;
+	
+	return 0;
+}
+
+int raw_release(struct inode *inode, struct file *filp)
+{
+	int minor;
+	kdev_t bdev;
+	
+	minor = MINOR(inode->i_rdev);
+	bdev = raw_device_bindings[minor];
+	bdev_close(bdev);
+	raw_device_inuse[minor]--;
+	return 0;
+}
+
+
+
+/*
+ * Deal with ioctls against the raw-device control interface, to bind
+ * and unbind other raw devices.  
+ */
+
+int raw_ctl_ioctl(struct inode *inode, 
+		  struct file *flip,
+		  unsigned int command, 
+		  unsigned long arg)
+{
+	struct raw_config_request rq;
+	int err = 0;
+	int minor;
+	
+	switch (command) {
+	case RAW_SETBIND:
+	case RAW_GETBIND:
+
+		/* First, find out which raw minor we want */
+
+		err = copy_from_user(&rq, (void *) arg, sizeof(rq));
+		if (err)
+			break;
+		
+		minor = rq.raw_minor;
+		if (minor == 0 || minor > MINORMASK) {
+			err = -EINVAL;
+			break;
+		}
+
+		if (command == RAW_SETBIND) {
+			/* 
+			 * For now, we don't need to check that the underlying
+			 * block device is present or not: we can do that when
+			 * the raw device is opened.  Just check that the
+			 * major/minor numbers make sense. 
+			 */
+
+			if (rq.block_major == NODEV || 
+			    rq.block_major > MAX_BLKDEV ||
+			    rq.block_minor > MINORMASK) {
+				err = -EINVAL;
+				break;
+			}
+			
+			if (raw_device_inuse[minor]) {
+				err = -EBUSY;
+				break;
+			}
+			raw_device_bindings[minor] = 
+				MKDEV(rq.block_major, rq.block_minor);
+		} else {
+			rq.block_major = MAJOR(raw_device_bindings[minor]);
+			rq.block_minor = MINOR(raw_device_bindings[minor]);
+			err = copy_to_user((void *) arg, &rq, sizeof(rq));
+		}
+		break;
+		
+	default:
+		err = -EINVAL;
+	}
+	
+	return err;
+}
+
+
+
+ssize_t	raw_read(struct file *filp, char * buf, 
+		 size_t size, loff_t *offp)
+{
+	return rw_raw_dev(READ, filp, buf, size, offp);
+}
+
+ssize_t	raw_write(struct file *filp, const char *buf, 
+		  size_t size, loff_t *offp)
+{
+	return rw_raw_dev(WRITE, filp, (char *) buf, size, offp);
+}
+
+#define SECTOR_BITS 9
+#define SECTOR_SIZE (1U << SECTOR_BITS)
+#define SECTOR_MASK (SECTOR_SIZE - 1)
+
+ssize_t	rw_raw_dev(int rw, struct file *filp, char *buf, 
+		   size_t size, loff_t *offp)
+{
+	struct kiobuf * iobuf;
+	int		err;
+	unsigned long	blocknr, blocks;
+	unsigned long	b[KIO_MAX_SECTORS];
+	size_t		transferred;
+	int		iosize;
+	int		i;
+	int		minor;
+	kdev_t		dev;
+	unsigned long	limit;
+
+	int		sector_size, sector_bits, sector_mask;
+	int		max_sectors;
+	
+	/*
+	 * First, a few checks on device size limits 
+	 */
+
+	minor = MINOR(filp->f_dentry->d_inode->i_rdev);
+	dev = raw_device_bindings[minor];
+	sector_size = raw_device_sector_size[minor];
+	sector_bits = raw_device_sector_bits[minor];
+	sector_mask = sector_size- 1;
+	max_sectors = KIO_MAX_SECTORS >> (sector_bits - 9);
+	
+	if (blk_size[MAJOR(dev)])
+		limit = (((loff_t) blk_size[MAJOR(dev)][MINOR(dev)]) << BLOCK_SIZE_BITS) >> sector_bits;
+	else
+		limit = INT_MAX;
+	dprintk ("rw_raw_dev: dev %d:%d (+%d)\n",
+		 MAJOR(dev), MINOR(dev), limit);
+	
+	if ((*offp & sector_mask) || (size & sector_mask))
+		return -EINVAL;
+	if ((*offp >> sector_bits) > limit)
+		return 0;
+
+	/* 
+	 * We'll just use one kiobuf
+	 */
+
+	err = alloc_kiovec(1, &iobuf);
+	if (err)
+		return err;
+
+	/*
+	 * Split the IO into KIO_MAX_SECTORS chunks, mapping and
+	 * unmapping the single kiobuf as we go to perform each chunk of
+	 * IO.  
+	 */
+
+	transferred = 0;
+	blocknr = *offp >> sector_bits;
+	while (size > 0) {
+		blocks = size >> sector_bits;
+		if (blocks > max_sectors)
+			blocks = max_sectors;
+		if (blocks > limit - blocknr)
+			blocks = limit - blocknr;
+		if (!blocks)
+			break;
+
+		iosize = blocks << sector_bits;
+
+		err = map_user_kiobuf(rw, iobuf, (unsigned long) buf, iosize);
+		if (err)
+			break;
+		
+		for (i=0; i < blocks; i++) 
+			b[i] = blocknr++;
+		
+		err = brw_kiovec(rw, 1, &iobuf, dev, b, sector_size, 0);
+
+		if (err >= 0) {
+			transferred += err;
+			size -= err;
+			buf += err;
+		}
+
+		unmap_kiobuf(iobuf);
+
+		if (err != iosize)
+			break;
+	}
+	
+	free_kiovec(1, &iobuf);
+
+	if (transferred) {
+		*offp += transferred;
+		return transferred;
+	}
+	
+	return err;
+}