Commit 699cf824 authored by Bernd Schubert's avatar Bernd Schubert Committed by Miklos Szeredi
Browse files

fuse: create helper function if DIO write needs exclusive lock 



This makes the code a bit easier to read and allows to more easily add more
conditions when an exclusive lock is needed.

Signed-off-by: default avatarBernd Schubert <bschubert@ddn.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 9511176b

fs/fuse/file.c

+45 −18
Original line number Diff line number Diff line
@@ -1299,6 +1299,47 @@ static ssize_t fuse_perform_write(struct kiocb *iocb, struct iov_iter *ii) 
	return res;

}



static bool fuse_io_past_eof(struct kiocb *iocb, struct iov_iter *iter)

{

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



	return iocb->ki_pos + iov_iter_count(iter) > i_size_read(inode);

}



/*

 * @return true if an exclusive lock for direct IO writes is needed

 */

static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from)

{

	struct file *file = iocb->ki_filp;

	struct fuse_file *ff = file->private_data;

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



	/* Server side has to advise that it supports parallel dio writes. */

	if (!(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES))

		return true;



	/*

	 * Append will need to know the eventual EOF - always needs an

	 * exclusive lock.

	 */

	if (iocb->ki_flags & IOCB_APPEND)

		return true;



	/*

	 * Combination of page access and direct-io is difficult, shared locks

	 * actually introduce a conflict.

	 */

	if (get_fuse_conn(inode)->direct_io_allow_mmap)

		return true;



	/* Parallel dio beyond EOF is not supported, at least for now. */

	if (fuse_io_past_eof(iocb, from))

		return true;



	return false;

}



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

{

	struct file *file = iocb->ki_filp;
@@ -1558,26 +1599,12 @@ static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	return res;

}



static bool fuse_direct_write_extending_i_size(struct kiocb *iocb,

					       struct iov_iter *iter)

{

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



	return iocb->ki_pos + iov_iter_count(iter) > i_size_read(inode);

}



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

{

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

	struct file *file = iocb->ki_filp;

	struct fuse_file *ff = file->private_data;

	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);

	ssize_t res;

	bool exclusive_lock =

		!(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) ||

		get_fuse_conn(inode)->direct_io_allow_mmap ||

		iocb->ki_flags & IOCB_APPEND ||

		fuse_direct_write_extending_i_size(iocb, from);

	bool exclusive_lock = fuse_dio_wr_exclusive_lock(iocb, from);



	/*

	 * Take exclusive lock if
@@ -1591,10 +1618,10 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	else {

		inode_lock_shared(inode);



		/* A race with truncate might have come up as the decision for

		 * the lock type was done without holding the lock, check again.

		/*

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

		 */

		if (fuse_direct_write_extending_i_size(iocb, from)) {

		if (fuse_io_past_eof(iocb, from)) {

			inode_unlock_shared(inode);

			inode_lock(inode);

			exclusive_lock = true;