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configfs: restore the kernel v5.13 text attribute write behavior 

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.

Reported-by: Bodo Stroesser <bostroesser@gmail.com>
Tested-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Bart Van Assche 2021-08-04 21:35:01 -07:00 committed by Christoph Hellwig
parent 36a21d5172
commit 769f526767
1 changed files with 6 additions and 12 deletions
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18
fs/configfs/file.c
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@ -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)