Return short read or 0 at end of a raw device, not EIO

Author: David Jeffery <djeffery@redhat.com>
Changes to the basic direct I/O code have broken the raw driver when reading
to the end of a raw device.  Instead of returning a short read for a read that
extends partially beyond the device's end or 0 when at the end of the device,
these reads now return EIO.

The raw driver needs the same end of device handling as was added for normal
block devices.  Using blkdev_read_iter, which has the needed size checks,
prevents the EIO conditions at the end of the device.

Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/char/raw.c b/drivers/char/raw.c
index 0102dc788608ec0060cf2fe1666e058c2d2d8076..a24891b97547dcf87cb91b52401e63f4d9dc50a2 100644 (file)
--- a/drivers/char/raw.c
+++ b/drivers/char/raw.c
@@ -285,7 +285,7 @@ static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
 
 static const struct file_operations raw_fops = {
        .read           = new_sync_read,
-       .read_iter      = generic_file_read_iter,
+       .read_iter      = blkdev_read_iter,
        .write          = new_sync_write,
        .write_iter     = blkdev_write_iter,
        .fsync          = blkdev_fsync,

diff --git a/fs/block_dev.c b/fs/block_dev.c
index cc9d4114cda085e1f0edac3b1d80341c8db75b58..1d9c9f3754f860b2f9ca19a61d1e89d3eaa9c47c 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1585,7 +1585,7 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 }
 EXPORT_SYMBOL_GPL(blkdev_write_iter);
 
-static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
+ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
        struct file *file = iocb->ki_filp;
        struct inode *bd_inode = file->f_mapping->host;
@@ -1599,6 +1599,7 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
        iov_iter_truncate(to, size);
        return generic_file_read_iter(iocb, to);
 }
+EXPORT_SYMBOL_GPL(blkdev_read_iter);
 
 /*
  * Try to release a page associated with block device when the system

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 01036262095fbbb0b0f6eb80cd3566123e04a50f..9ab779e8a63ccd7785637dd9017fc3bc69ff260f 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2469,6 +2469,7 @@ extern ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo
 extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
 
 /* fs/block_dev.c */
+extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
 extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);
 extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
                        int datasync);