Fix a crash when block device is read and block size is changed at the same time

[cascardo/linux.git] / include / linux / fs.h

diff --git a/include/linux/fs.h b/include/linux/fs.h
index bd6f6e7..e60bbd0 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -725,6 +725,8 @@ struct block_device {
        int                     bd_fsfreeze_count;
        /* Mutex for freeze */
        struct mutex            bd_fsfreeze_mutex;
+       /* A semaphore that prevents I/O while block size is being changed */
+       struct rw_semaphore     bd_block_size_semaphore;
 };
 
 /*
@@ -2565,6 +2567,8 @@ 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_read(struct kiocb *iocb, const struct iovec *iov,
+                              unsigned long nr_segs, loff_t pos);
 extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
                                unsigned long nr_segs, loff_t pos);
 extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,