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

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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 @@ out:
return retval; return retval;
} }
/* Fill [buffer, buffer + pos) with data coming from @from. */ /* Fill @buffer with data coming from @from. */
static int fill_write_buffer(struct configfs_buffer *buffer, loff_t pos, static int fill_write_buffer(struct configfs_buffer *buffer,
struct iov_iter *from) struct iov_iter *from)
{ {
loff_t to_copy;
int copied; int copied;
u8 *to;
if (!buffer->page) if (!buffer->page)
buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0); buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
if (!buffer->page) if (!buffer->page)
return -ENOMEM; return -ENOMEM;
to_copy = SIMPLE_ATTR_SIZE - 1 - pos; copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
if (to_copy <= 0)
return 0;
to = buffer->page + pos;
copied = copy_from_iter(to, to_copy, from);
buffer->needs_read_fill = 1; buffer->needs_read_fill = 1;
/* if buf is assumed to contain a string, terminate it by \0, /* if buf is assumed to contain a string, terminate it by \0,
* so e.g. sscanf() can scan the string easily */ * so e.g. sscanf() can scan the string easily */
to[copied] = 0; buffer->page[copied] = 0;
return copied ? : -EFAULT; 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 file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data; struct configfs_buffer *buffer = file->private_data;
ssize_t len; int len;
mutex_lock(&buffer->mutex); mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, iocb->ki_pos, from); len = fill_write_buffer(buffer, from);
if (len > 0) if (len > 0)
len = flush_write_buffer(file, buffer, len); len = flush_write_buffer(file, buffer, len);
if (len > 0) if (len > 0)