[PATCH] fix the raw driver

Fix the raw driver by tricking it into performing O_DIRECT IO against
the bound blockdev.

- rewrite the i_mapping for /dev/raw/raw0 to point at the same thing
  as bdev->bd_inode->i_mapping.  We've performed a bdget() against the
  blockdev, which should pin it for the correct lifetime.

- set the O_DIRECT bit on the caller's file->flags.

diff --git a/drivers/char/raw.c b/drivers/char/raw.c
index e46835a29d94292108b786013d8ab0ec3b5f5133..edf88173f0e1249e8a486cd512302f4cabb2b83c 100644 (file)
--- a/drivers/char/raw.c
+++ b/drivers/char/raw.c
@@ -30,6 +30,10 @@ static struct file_operations raw_ctl_fops;
 /*
  * Open/close code for raw IO.
  *
+ * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
+ * point at the blockdev's address_space and set the file handle to use
+ * O_DIRECT.
+ *
  * Set the device's soft blocksize to the minimum possible.  This gives the
  * finest possible alignment and has no adverse impact on performance.
  */
@@ -56,7 +60,12 @@ static int raw_open(struct inode *inode, struct file *filp)
                err = blkdev_get(bdev, filp->f_mode, 0, BDEV_RAW);
                if (!err) {
                        err = set_blocksize(bdev, bdev_hardsect_size(bdev));
-                       raw_devices[minor].inuse++;
+                       if (err == 0) {
+                               raw_devices[minor].inuse++;
+                               filp->f_dentry->d_inode->i_mapping =
+                                       bdev->bd_inode->i_mapping;
+                               filp->f_flags |= O_DIRECT;
+                       }
                }
        }
        up(&raw_mutex);
@@ -200,72 +209,22 @@ out:
        return err;
 }
 
-static ssize_t
-rw_raw_dev(int rw, struct file *filp, const struct iovec *iov, unsigned long nr_segs, loff_t *offp)
-{
-       const int minor = minor(filp->f_dentry->d_inode->i_rdev);
-       struct block_device *bdev = raw_devices[minor].binding;
-       struct inode *inode = bdev->bd_inode;
-       size_t count = iov_length(iov, nr_segs); 
-       ssize_t ret = 0;
-
-       if (count == 0)
-               goto out;       
-
-       if ((ssize_t)count < 0)
-               return -EINVAL; 
-
-       if (*offp >= inode->i_size) 
-               return -ENXIO;
-
-       if (count + *offp > inode->i_size) {
-               count = inode->i_size - *offp;
-               nr_segs = iov_shorten((struct iovec *)iov, nr_segs, count);
-       }
-       ret = generic_file_direct_IO(rw, filp, iov, *offp, nr_segs);
-
-       if (ret > 0)
-               *offp += ret;
-out:
-       return ret;
-}
-
-static ssize_t
-raw_read(struct file *filp, char *buf, size_t size, loff_t *offp)
-{
-       struct iovec local_iov = { .iov_base = buf, .iov_len = size};
-
-       return rw_raw_dev(READ, filp, &local_iov, 1, offp);
-}
-
-static ssize_t
-raw_write(struct file *filp, const char *buf, size_t size, loff_t *offp)
+static ssize_t raw_file_write(struct file *file, const char *buf,
+                                  size_t count, loff_t *ppos)
 {
-       struct iovec local_iov = { .iov_base = (char *)buf, .iov_len = size};
+       struct iovec local_iov = { .iov_base = (void *)buf, .iov_len = count };
 
-       return rw_raw_dev(WRITE, filp, &local_iov, 1, offp);
-}
-
-static ssize_t 
-raw_readv(struct file *filp, const struct iovec *iov, unsigned long nr_segs, loff_t *offp) 
-{
-       return rw_raw_dev(READ, filp, iov, nr_segs, offp);
-}
-
-static ssize_t 
-raw_writev(struct file *filp, const struct iovec *iov, unsigned long nr_segs, loff_t *offp) 
-{
-       return rw_raw_dev(WRITE, filp, iov, nr_segs, offp);
+       return generic_file_write_nolock(file, &local_iov, 1, ppos);
 }
 
 static struct file_operations raw_fops = {
-       .read   =       raw_read,
-       .write  =       raw_write,
+       .read   =       generic_file_read,
+       .write  =       raw_file_write,
        .open   =       raw_open,
        .release=       raw_release,
        .ioctl  =       raw_ioctl,
-       .readv  =       raw_readv,
-       .writev =       raw_writev,
+       .readv  =       generic_file_readv,
+       .writev =       generic_file_writev,
        .owner  =       THIS_MODULE,
 };