Sorry for the latency. I was away last week.
On Fri, Oct 25, 2013 at 11:37:53AM -0400, Josef Bacik wrote:
> Apparently we don't actually close the files until we return to userspace, so
> stop using vfs_read in send. This is actually better for us since we can avoid
> all the extra logic of holding the file we're sending open and making sure to
> clean it up.
Good stuff.
A few things:
> + pgoff_t index = offset >> PAGE_CACHE_SHIFT;
> + pgoff_t last_index;
> + unsigned pg_offset = offset & (PAGE_CACHE_SIZE - 1);
unsigned pg_offset = offset & ~PAGE_CACHE_MASK;
> + if (offset + len > i_size_read(inode)) {
I worry about offset + len wrapping but I didn't check the caller to see
if that's possible.
> + while (index <= last_index) {
> + unsigned cur_len = min_t(unsigned, len, PAGE_CACHE_SIZE);
Careful, this'd insert some random kernel memory after the first partial
page.
unsigned cur_len = min_t(unsigned, len, PAGE_CACHE_SIZE - pg_off);
> + addr = kmap(page);
> + memcpy(sctx->read_buf + ret, addr + pg_offset, cur_len);
> + kunmap(page);
> + unlock_page(page);
I think you need flush_dcache_page() before reading from user mappable
page cache pages. (Need to make sure that potential cached stores at
other user virtual addreses are flushed before we read from the kernel
mapping.)
- z
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