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From: Bart Van Assche <bvanassche@acm.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Joel Becker <jlbec@evilplan.org>,
	linux-kernel@vger.kernel.org,
	Bodo Stroesser <bostroesser@gmail.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	Yanko Kaneti <yaneti@declera.com>,
	Brendan Higgins <brendanhiggins@google.com>,
	Bart Van Assche <bvanassche@acm.org>
Subject: [PATCH 2/4] configfs: Fix writing at a non-zero offset
Date: Fri, 23 Jul 2021 14:23:51 -0700	[thread overview]
Message-ID: <20210723212353.896343-3-bvanassche@acm.org> (raw)
In-Reply-To: <20210723212353.896343-1-bvanassche@acm.org>

Store data at the right offset when writing with a non-zero offset. I think
this patch fixes behavior introduced in the initial configfs commit. From a
source code comment in the initial configfs commit: "There is no easy way
for us to know if userspace is only doing a partial write, so we don't
support them."

Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Yanko Kaneti <yaneti@declera.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 fs/configfs/file.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 8121bb1b2121..3b2ddc2e5d42 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -226,14 +226,16 @@ static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
 	struct configfs_buffer *buffer = file->private_data;
-	ssize_t len;
+	int len, written = 0;
 
 	mutex_lock(&buffer->mutex);
 	len = fill_write_buffer(buffer, iocb->ki_pos, from);
 	if (len > 0)
-		len = flush_write_buffer(file, buffer, len);
-	if (len > 0)
-		iocb->ki_pos += len;
+		written = flush_write_buffer(file, buffer, iocb->ki_pos + len);
+	if (written > 0) {
+		len = max_t(int, 0, written - iocb->ki_pos);
+		iocb->ki_pos = written;
+	}
 	mutex_unlock(&buffer->mutex);
 	return len;
 }

  parent reply	other threads:[~2021-07-23 21:24 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 21:23 [PATCH 0/4] Improve the configfs read and write iterators further Bart Van Assche
2021-07-23 21:23 ` [PATCH 1/4] configfs: Rework the overflow check in fill_write_buffer() Bart Van Assche
2021-07-23 21:23 ` Bart Van Assche [this message]
2021-07-26 14:58   ` [PATCH 2/4] configfs: Fix writing at a non-zero offset Bodo Stroesser
2021-07-26 16:26     ` Bart Van Assche
2021-07-26 21:13       ` Bodo Stroesser
2021-07-26 21:52         ` Bart Van Assche
2021-07-27  0:54           ` Bodo Stroesser
2021-07-27  3:17             ` Bart Van Assche
2021-07-27  7:27               ` Bodo Stroesser
2021-07-27 16:47                 ` Bart Van Assche
2021-07-28 17:14                   ` Bodo Stroesser
2021-07-28 17:55                     ` Bart Van Assche
2021-07-23 21:23 ` [PATCH 3/4] kunit: Add support for suite initialization and cleanup Bart Van Assche
2021-07-27 21:26   ` Brendan Higgins
2021-07-29  3:33     ` Bart Van Assche
2021-07-23 21:23 ` [PATCH 4/4] configfs: Add unit tests Bart Van Assche

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