On Wed, 15 Jan 2014, Matthew Wilcox wrote:
> static ssize_t xip_io(int rw, struct inode *inode, const struct iovec
> *iov,
> loff_t start, loff_t end, unsigned nr_segs,
> get_block_t get_block, struct buffer_head *bh)
> @@ -103,21 +109,29 @@ static ssize_t xip_io(int rw, struct inode *inode,
> const struct iovec *iov,
> retval = get_block(inode, block, bh, rw == WRITE);
> if (retval)
> break;
> - if (buffer_mapped(bh)) {
> - retval = xip_get_addr(inode, bh, &addr);
> - if (retval < 0)
> - break;
> - addr += offset - (block << inode->i_blkbits);
> - hole = false;
> - size = retval;
> - } else {
> - if (rw == WRITE) {
> + if (rw == WRITE) {
> + if (!buffer_mapped(bh)) {
> retval = -EIO;
> break;
> }
> + hole = false;
> + } else {
> + hole = !buffer_written(bh);
> + }
> +
> + if (hole) {
> addr = NULL;
> - hole = true;
> size = bh->b_size;
> + } else {
> + unsigned first;
> + retval = xip_get_addr(inode, bh, &addr);
> + if (retval < 0)
> + break;
> + size = retval;
> + first = offset - (block << inode->i_blkbits);
> + if (buffer_unwritten(bh))
> + memset(addr, 0, first);
> + addr += first;
+ size -= first;
This is needed so that we don't overrun the XIP buffer we are given in the
event that our user buffer >= our XIP buffer and the start of our I/O isn't
block aligned.
You can add my
Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Thanks,
- Ross
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