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Commit 92ce4728 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

aio: remove the extra get_file/fput pair in io_submit_one 



If we release the lockdep write protection token before calling into
->write_iter and thus never access the file pointer after an -EIOCBQUEUED
return from ->write_iter or ->read_iter we don't need this extra
reference.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 75321b50

fs/aio.c

+16 −9
Original line number Diff line number Diff line
@@ -1515,17 +1515,20 @@ static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored, 
		return ret;

	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));

	if (!ret) {

		req->ki_flags |= IOCB_WRITE;

		file_start_write(file);

		ret = aio_ret(req, call_write_iter(file, req, &iter));

		/*

		 * We release freeze protection in aio_complete().  Fool lockdep

		 * by telling it the lock got released so that it doesn't

		 * complain about held lock when we return to userspace.

		 * Open-code file_start_write here to grab freeze protection,

		 * which will be released by another thread in aio_complete().

		 * Fool lockdep by telling it the lock got released so that it

		 * doesn't complain about the held lock when we return to

		 * userspace.

		 */

		if (S_ISREG(file_inode(file)->i_mode))

		if (S_ISREG(file_inode(file)->i_mode)) {

			__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);

			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);

		}

		req->ki_flags |= IOCB_WRITE;

		ret = aio_ret(req, call_write_iter(file, req, &iter));

	}

	kfree(iovec);

	return ret;

}
@@ -1599,7 +1602,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 
	req->ki_user_iocb = user_iocb;

	req->ki_user_data = iocb->aio_data;



	get_file(file);

	switch (iocb->aio_lio_opcode) {

	case IOCB_CMD_PREAD:

		ret = aio_read(&req->common, iocb, false, compat);
@@ -1618,8 +1620,13 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 
		ret = -EINVAL;

		break;

	}

	fput(file);



	/*

	 * If ret is -EIOCBQUEUED, ownership of the file reference acquired

	 * above passed to the file system, which at this point might have

	 * dropped the reference, so we must be careful to not reference it

	 * once we have called into the file system.

	 */

	if (ret && ret != -EIOCBQUEUED)

		goto out_put_req;

	return 0;