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Commit 728fbc0e authored by Goldwyn Rodrigues's avatar Goldwyn Rodrigues Committed by Jens Axboe
Browse files

ext4: nowait aio support 



Return EAGAIN if any of the following checks fail for direct I/O:
  + i_rwsem is lockable
  + Writing beyond end of file (will trigger allocation)
  + Blocks are not allocated at the write location

Signed-off-by: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 03a07c92

fs/ext4/file.c

+29 −6
Original line number Diff line number Diff line
@@ -37,7 +37,11 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	struct inode *inode = file_inode(iocb->ki_filp);

	ssize_t ret;



	if (!inode_trylock_shared(inode)) {

		if (iocb->ki_flags & IOCB_NOWAIT)

			return -EAGAIN;

		inode_lock_shared(inode);

	}

	/*

	 * Recheck under inode lock - at this point we are sure it cannot

	 * change anymore
@@ -179,7 +183,11 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	struct inode *inode = file_inode(iocb->ki_filp);

	ssize_t ret;



	if (!inode_trylock(inode)) {

		if (iocb->ki_flags & IOCB_NOWAIT)

			return -EAGAIN;

		inode_lock(inode);

	}

	ret = ext4_write_checks(iocb, from);

	if (ret <= 0)

		goto out;
@@ -216,7 +224,12 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
		return ext4_dax_write_iter(iocb, from);

#endif



	if (!inode_trylock(inode)) {

		if (iocb->ki_flags & IOCB_NOWAIT)

			return -EAGAIN;

		inode_lock(inode);

	}



	ret = ext4_write_checks(iocb, from);

	if (ret <= 0)

		goto out;
@@ -235,9 +248,15 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 


	iocb->private = &overwrite;

	/* Check whether we do a DIO overwrite or not */

	if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&

	    ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))

	if (o_direct && !unaligned_aio) {

		if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {

			if (ext4_should_dioread_nolock(inode))

				overwrite = 1;

		} else if (iocb->ki_flags & IOCB_NOWAIT) {

			ret = -EAGAIN;

			goto out;

		}

	}



	ret = __generic_file_write_iter(iocb, from);

	inode_unlock(inode);
@@ -435,6 +454,10 @@ static int ext4_file_open(struct inode * inode, struct file * filp) 
		if (ret < 0)

			return ret;

	}



	/* Set the flags to support nowait AIO */

	filp->f_mode |= FMODE_AIO_NOWAIT;



	return dquot_file_open(inode, filp);

}