kill generic_segment_checks()

all callers of ->aio_read() and ->aio_write() have iov/nr_segs already
checked - generic_segment_checks() done after that is just an odd way
to spell iov_length().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/staging/lustre/lustre/llite/file.c

@@ -1180,9 +1180,7 @@ static ssize_t ll_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 	ssize_t	     result;
 	int		 refcheck;
 
-	result = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
-	if (result)
-		return result;
+	count = iov_length(iov, nr_segs);
 
 	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
@@ -1235,14 +1233,10 @@ static ssize_t ll_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 {
 	struct lu_env      *env;
 	struct vvp_io_args *args;
-	size_t	      count = 0;
+	size_t	      count = iov_length(iov, nr_segs);
 	ssize_t	     result;
 	int		 refcheck;
 
-	result = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
-	if (result)
-		return result;
-
 	env = cl_env_get(&refcheck);
 	if (IS_ERR(env))
 		return PTR_ERR(env);

fs/btrfs/file.c

@@ -1726,12 +1726,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 
 	mutex_lock(&inode->i_mutex);
 
-	err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
-	if (err) {
-		mutex_unlock(&inode->i_mutex);
-		goto out;
-	}
-	count = ocount;
+	count = ocount = iov_length(iov, nr_segs);
 
 	current->backing_dev_info = inode->i_mapping->backing_dev_info;
 	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));

fs/ceph/file.c

@@ -828,12 +828,8 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
 		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
 		     ceph_cap_string(got));
 
-		if (!read) {
-			ret = generic_segment_checks(iov, &nr_segs,
-							&len, VERIFY_WRITE);
-			if (ret)
-				goto out;
-		}
+		if (!read)
+			len = iov_length(iov, nr_segs);
 
 		iov_iter_init(&i, iov, nr_segs, len, read);
 
@@ -855,7 +851,6 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
 
 		ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
 	}
-out:
 	dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
 	     inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
 	ceph_put_cap_refs(ci, got);
@@ -911,9 +906,7 @@ static ssize_t ceph_aio_write(struct kiocb *iocb, const struct iovec *iov,
 
 	mutex_lock(&inode->i_mutex);
 
-	err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
-	if (err)
-		goto out;
+	count = iov_length(iov, nr_segs);
 
 	/* We can write back this queue in page reclaim */
 	current->backing_dev_info = file->f_mapping->backing_dev_info;

fs/fuse/file.c

@@ -1208,12 +1208,7 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 
 	WARN_ON(iocb->ki_pos != pos);
 
-	ocount = 0;
-	err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
-	if (err)
-		return err;
-
-	count = ocount;
+	count = ocount = iov_length(iov, nr_segs);
 	mutex_lock(&inode->i_mutex);
 
 	/* We can write back this queue in page reclaim */

fs/ntfs/file.c

@@ -2091,10 +2091,7 @@ static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
 	size_t count;		/* after file limit checks */
 	ssize_t written, err;
 
-	count = 0;
-	err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
-	if (err)
-		return err;
+	count = iov_length(iov, nr_segs);
 	pos = *ppos;
 	/* We can write back this queue in page reclaim. */
 	current->backing_dev_info = mapping->backing_dev_info;

fs/ocfs2/file.c

@@ -2355,12 +2355,7 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
 	/* communicate with ocfs2_dio_end_io */
 	ocfs2_iocb_set_rw_locked(iocb, rw_level);
 
-	ret = generic_segment_checks(iov, &nr_segs, &ocount,
-				     VERIFY_READ);
-	if (ret)
-		goto out_dio;
-
-	count = ocount;
+	count = ocount = iov_length(iov, nr_segs);
 	ret = generic_write_checks(file, ppos, &count,
 				   S_ISBLK(inode->i_mode));
 	if (ret)

fs/xfs/xfs_file.c

@@ -253,9 +253,7 @@ xfs_file_aio_read(
 	if (file->f_mode & FMODE_NOCMTIME)
 		ioflags |= IO_INVIS;
 
-	ret = generic_segment_checks(iovp, &nr_segs, &size, VERIFY_WRITE);
-	if (ret < 0)
-		return ret;
+	size = iov_length(iovp, nr_segs);
 
 	if (unlikely(ioflags & IO_ISDIRECT)) {
 		xfs_buftarg_t	*target =
@@ -777,10 +775,7 @@ xfs_file_aio_write(
 
 	BUG_ON(iocb->ki_pos != pos);
 
-	ret = generic_segment_checks(iovp, &nr_segs, &ocount, VERIFY_READ);
-	if (ret)
-		return ret;
-
+	ocount = iov_length(iovp, nr_segs);
 	if (ocount == 0)
 		return 0;
 

include/linux/fs.h

@@ -2412,8 +2412,6 @@ extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *,
 extern ssize_t generic_perform_write(struct file *, struct iov_iter *, loff_t);
 extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
 extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
-extern int generic_segment_checks(const struct iovec *iov,
-		unsigned long *nr_segs, size_t *count, int access_flags);
 
 /* fs/block_dev.c */
 extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,

mm/filemap.c

@@ -1663,45 +1663,6 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
 	return written ? written : error;
 }
 
-/*
- * Performs necessary checks before doing a write
- * @iov:	io vector request
- * @nr_segs:	number of segments in the iovec
- * @count:	number of bytes to write
- * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
- *
- * Adjust number of segments and amount of bytes to write (nr_segs should be
- * properly initialized first). Returns appropriate error code that caller
- * should return or zero in case that write should be allowed.
- */
-int generic_segment_checks(const struct iovec *iov,
-			unsigned long *nr_segs, size_t *count, int access_flags)
-{
-	unsigned long   seg;
-	size_t cnt = 0;
-	for (seg = 0; seg < *nr_segs; seg++) {
-		const struct iovec *iv = &iov[seg];
-
-		/*
-		 * If any segment has a negative length, or the cumulative
-		 * length ever wraps negative then return -EINVAL.
-		 */
-		cnt += iv->iov_len;
-		if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
-			return -EINVAL;
-		if (access_ok(access_flags, iv->iov_base, iv->iov_len))
-			continue;
-		if (seg == 0)
-			return -EFAULT;
-		*nr_segs = seg;
-		cnt -= iv->iov_len;	/* This segment is no good */
-		break;
-	}
-	*count = cnt;
-	return 0;
-}
-EXPORT_SYMBOL(generic_segment_checks);
-
 /**
  * generic_file_aio_read - generic filesystem read routine
  * @iocb:	kernel I/O control block
@@ -1717,15 +1678,12 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 		unsigned long nr_segs, loff_t pos)
 {
 	struct file *filp = iocb->ki_filp;
-	ssize_t retval;
+	ssize_t retval = 0;
 	size_t count;
 	loff_t *ppos = &iocb->ki_pos;
 	struct iov_iter i;
 
-	count = 0;
-	retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
-	if (retval)
-		return retval;
+	count = iov_length(iov, nr_segs);
 	iov_iter_init(&i, iov, nr_segs, count, 0);
 
 	/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
@@ -2615,12 +2573,7 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	ssize_t		status;
 	struct iov_iter from;
 
-	ocount = 0;
-	err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
-	if (err)
-		return err;
-
-	count = ocount;
+	count = ocount = iov_length(iov, nr_segs);
 
 	/* We can write back this queue in page reclaim */
 	current->backing_dev_info = mapping->backing_dev_info;

mm/shmem.c

@@ -1412,14 +1412,11 @@ static ssize_t shmem_file_aio_read(struct kiocb *iocb,
 	unsigned long offset;
 	enum sgp_type sgp = SGP_READ;
 	int error = 0;
-	ssize_t retval;
-	size_t count;
+	ssize_t retval = 0;
+	size_t count = iov_length(iov, nr_segs);
 	loff_t *ppos = &iocb->ki_pos;
 	struct iov_iter iter;
 
-	retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
-	if (retval)
-		return retval;
 	iov_iter_init(&iter, iov, nr_segs, count, 0);
 
 	/*