Commit 9bbb6717 authored by Bernd Schubert's avatar Bernd Schubert Committed by Miklos Szeredi
Browse files

fuse: add fuse_dio_lock/unlock helper functions 



So far this is just a helper to remove complex locking logic out of
fuse_direct_write_iter.  Especially needed by the next patch in the series
to that adds the fuse inode cache IO mode and adds in even more locking
complexity.

Signed-off-by: default avatarBernd Schubert <bschubert@ddn.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 699cf824

fs/fuse/file.c

+34 −27
Original line number Diff line number Diff line
@@ -1340,6 +1340,37 @@ static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from 
	return false;

}



static void fuse_dio_lock(struct kiocb *iocb, struct iov_iter *from,

			  bool *exclusive)

{

	struct inode *inode = file_inode(iocb->ki_filp);



	*exclusive = fuse_dio_wr_exclusive_lock(iocb, from);

	if (*exclusive) {

		inode_lock(inode);

	} else {

		inode_lock_shared(inode);

		/*

		 * Previous check was without inode lock and might have raced,

		 * check again.

		 */

		if (fuse_io_past_eof(iocb, from)) {

			inode_unlock_shared(inode);

			inode_lock(inode);

			*exclusive = true;

		}

	}

}



static void fuse_dio_unlock(struct inode *inode, bool exclusive)

{

	if (exclusive) {

		inode_unlock(inode);

	} else {

		inode_unlock_shared(inode);

	}

}



static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)

{

	struct file *file = iocb->ki_filp;
@@ -1604,30 +1635,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	struct inode *inode = file_inode(iocb->ki_filp);

	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);

	ssize_t res;

	bool exclusive_lock = fuse_dio_wr_exclusive_lock(iocb, from);



	/*

	 * Take exclusive lock if

	 * - Parallel direct writes are disabled - a user space decision

	 * - Parallel direct writes are enabled and i_size is being extended.

	 * - Shared mmap on direct_io file is supported (FUSE_DIRECT_IO_ALLOW_MMAP).

	 *   This might not be needed at all, but needs further investigation.

	 */

	if (exclusive_lock)

		inode_lock(inode);

	else {

		inode_lock_shared(inode);



		/*

		 * Previous check was without any lock and might have raced.

		 */

		if (fuse_io_past_eof(iocb, from)) {

			inode_unlock_shared(inode);

			inode_lock(inode);

			exclusive_lock = true;

		}

	}

	bool exclusive;



	fuse_dio_lock(iocb, from, &exclusive);

	res = generic_write_checks(iocb, from);

	if (res > 0) {

		if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
@@ -1638,10 +1648,7 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) 
			fuse_write_update_attr(inode, iocb->ki_pos, res);

		}

	}

	if (exclusive_lock)

		inode_unlock(inode);

	else

		inode_unlock_shared(inode);

	fuse_dio_unlock(inode, exclusive);



	return res;

}