lift generic_write_checks() into callers of __generic_file_write_iter()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/block_dev.c

@@ -1597,6 +1597,16 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct file *file = iocb->ki_filp;
 	struct blk_plug plug;
 	ssize_t ret;
+	size_t count = iov_iter_count(from);
+
+	ret = generic_write_checks(file, &iocb->ki_pos, &count, 1);
+	if (ret)
+		return ret;
+
+	if (count == 0)
+		return 0;
+
+	iov_iter_truncate(from, count);
 
 	blk_start_plug(&plug);
 	ret = __generic_file_write_iter(iocb, from);

fs/cifs/file.c

@@ -2673,8 +2673,8 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 	struct inode *inode = file->f_mapping->host;
 	struct cifsInodeInfo *cinode = CIFS_I(inode);
 	struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;
-	ssize_t rc = -EACCES;
-	loff_t lock_pos = iocb->ki_pos;
+	ssize_t rc;
+	size_t count;
 
 	/*
 	 * We need to hold the sem to be sure nobody modifies lock list
@@ -2682,23 +2682,30 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 	 */
 	down_read(&cinode->lock_sem);
 	mutex_lock(&inode->i_mutex);
-	if (file->f_flags & O_APPEND)
-		lock_pos = i_size_read(inode);
-	if (!cifs_find_lock_conflict(cfile, lock_pos, iov_iter_count(from),
+
+	count = iov_iter_count(from);
+	rc = generic_write_checks(file, &iocb->ki_pos, &count, 0);
+	if (rc)
+		goto out;
+
+	if (count == 0)
+		goto out;
+
+	iov_iter_truncate(from, count);
+
+	if (!cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from),
 				     server->vals->exclusive_lock_type, NULL,
-				     CIFS_WRITE_OP)) {
+				     CIFS_WRITE_OP))
 		rc = __generic_file_write_iter(iocb, from);
-		mutex_unlock(&inode->i_mutex);
-
-		if (rc > 0) {
-			ssize_t err;
+	else
+		rc = -EACCES;
+out:
+	mutex_unlock(&inode->i_mutex);
 
-			err = generic_write_sync(file, iocb->ki_pos - rc, rc);
-			if (err < 0)
-				rc = err;
-		}
-	} else {
-		mutex_unlock(&inode->i_mutex);
+	if (rc > 0) {
+		ssize_t err = generic_write_sync(file, iocb->ki_pos - rc, rc);
+		if (err < 0)
+			rc = err;
 	}
 	up_read(&cinode->lock_sem);
 	return rc;

fs/ext4/file.c

@@ -132,9 +132,8 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 			ret = -EFBIG;
 			goto errout;
 		}
-
-		if (pos + length > sbi->s_bitmap_maxbytes)
-			iov_iter_truncate(from, sbi->s_bitmap_maxbytes - pos);
+		iov_iter_truncate(from, sbi->s_bitmap_maxbytes - pos);
+		length = iov_iter_count(from);
 	}
 
 	iocb->private = &overwrite;
@@ -172,7 +171,16 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		}
 	}
 
+	ret = generic_write_checks(file, &iocb->ki_pos, &length, 0);
+	if (ret)
+		goto out;
+
+	if (length == 0)
+		goto out;
+
+	iov_iter_truncate(from, length);
 	ret = __generic_file_write_iter(iocb, from);
+out:
 	mutex_unlock(&inode->i_mutex);
 
 	if (ret > 0) {

fs/udf/file.c

@@ -151,7 +151,17 @@ static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	} else
 		up_write(&iinfo->i_data_sem);
 
+	retval = generic_write_checks(file, &iocb->ki_pos, &count, 0);
+	if (retval)
+		goto out;
+
+	if (count == 0)
+		goto out;
+
+	iov_iter_truncate(from, count);
+
 	retval = __generic_file_write_iter(iocb, from);
+out:
 	mutex_unlock(&inode->i_mutex);
 
 	if (retval > 0) {

mm/filemap.c

@@ -2560,19 +2560,9 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	ssize_t		written = 0;
 	ssize_t		err;
 	ssize_t		status;
-	size_t		count = iov_iter_count(from);
 
 	/* We can write back this queue in page reclaim */
 	current->backing_dev_info = inode_to_bdi(inode);
-	err = generic_write_checks(file, &iocb->ki_pos, &count, S_ISBLK(inode->i_mode));
-	if (err)
-		goto out;
-
-	if (count == 0)
-		goto out;
-
-	iov_iter_truncate(from, count);
-
 	err = file_remove_suid(file);
 	if (err)
 		goto out;
@@ -2651,9 +2641,14 @@ ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
 	ssize_t ret;
+	size_t count = iov_iter_count(from);
 
 	mutex_lock(&inode->i_mutex);
-	ret = __generic_file_write_iter(iocb, from);
+	ret = generic_write_checks(file, &iocb->ki_pos, &count, 0);
+	if (!ret && count) {
+		iov_iter_truncate(from, count);
+		ret = __generic_file_write_iter(iocb, from);
+	}
 	mutex_unlock(&inode->i_mutex);
 
 	if (ret > 0) {