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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>,
	Brendan Higgins <brendanhiggins@google.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Yanko Kaneti <yaneti@declera.com>
Subject: [PATCH v4 1/3] configfs: Restore the kernel v5.13 text attribute write behavior
Date: Wed,  4 Aug 2021 21:35:01 -0700	[thread overview]
Message-ID: <20210805043503.20252-2-bvanassche@acm.org> (raw)
In-Reply-To: <20210805043503.20252-1-bvanassche@acm.org>

Instead of appending new text attribute data at the offset specified by the
write() system call, only pass the newly written data to the .store()
callback.

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>
Reported-by: Bodo Stroesser <bostroesser@gmail.com>
Tested-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 fs/configfs/file.c | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 5a0be9985bae..0ad32150611e 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -177,28 +177,22 @@ static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	return retval;
 }
 
-/* Fill [buffer, buffer + pos) with data coming from @from. */
-static int fill_write_buffer(struct configfs_buffer *buffer, loff_t pos,
+/* Fill @buffer with data coming from @from. */
+static int fill_write_buffer(struct configfs_buffer *buffer,
 			     struct iov_iter *from)
 {
-	loff_t to_copy;
 	int copied;
-	u8 *to;
 
 	if (!buffer->page)
 		buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
 	if (!buffer->page)
 		return -ENOMEM;
 
-	to_copy = SIMPLE_ATTR_SIZE - 1 - pos;
-	if (to_copy <= 0)
-		return 0;
-	to = buffer->page + pos;
-	copied = copy_from_iter(to, to_copy, from);
+	copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
 	buffer->needs_read_fill = 1;
 	/* if buf is assumed to contain a string, terminate it by \0,
 	 * so e.g. sscanf() can scan the string easily */
-	to[copied] = 0;
+	buffer->page[copied] = 0;
 	return copied ? : -EFAULT;
 }
 
@@ -227,10 +221,10 @@ 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;
 
 	mutex_lock(&buffer->mutex);
-	len = fill_write_buffer(buffer, iocb->ki_pos, from);
+	len = fill_write_buffer(buffer, from);
 	if (len > 0)
 		len = flush_write_buffer(file, buffer, len);
 	if (len > 0)

  reply	other threads:[~2021-08-05  4:35 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05  4:35 [PATCH v4 0/3] " Bart Van Assche
2021-08-05  4:35 ` Bart Van Assche [this message]
2021-08-05  4:35 ` [PATCH v4 2/3] kunit: Add support for suite initialization and cleanup Bart Van Assche
2021-08-05  4:35 ` [PATCH v4 3/3] configfs: Add unit tests Bart Van Assche
2021-08-09 14:59   ` Christoph Hellwig
2021-08-09 18:31     ` Bart Van Assche
2021-08-10 16:50       ` Christoph Hellwig
2021-08-10 18:45         ` Bart Van Assche
2021-08-10 20:50           ` Shuah Khan
2021-08-11  9:00             ` Brendan Higgins
2021-08-10 22:00     ` Brendan Higgins
2021-08-11  3:13       ` Bart Van Assche
2021-08-09 14:56 ` [PATCH v4 0/3] Restore the kernel v5.13 text attribute write behavior Christoph Hellwig

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