midnight
On Fri, May 18, 2018 at 2:46 AM, Christoph Hellwig <hch(a)lst.de> wrote:
This looks reasonable to me. A few more comments below.
> This patch replaces and consolidates patch 2 [1] and 4 [2] from the v9
> series [3] for "dax: fix dma vs truncate/hole-punch".
Can you repost the whole series? Otherwise things might get a little
too confusing.
Sure thing.
> WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
> + return 0;
> } else if (pfn_t_devmap(pfn)) {
> + struct dev_pagemap *pgmap;
This should probably become something like:
bool supported = false;
...
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) {
...
supported = true;
} else if (pfn_t_devmap(pfn)) {
pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
supported = true;
put_dev_pagemap(pgmap);
}
if (!supported) {
pr_debug("VFS (%s): error: dax support not enabled\n",
sb->s_id);
return -EOPNOTSUPP;
}
return 0;
Looks good, will do.
> + select DEV_PAGEMAP_OPS if (ZONE_DEVICE &&
!FS_DAX_LIMITED)
Btw, what was the reason again we couldn't get rid of FS_DAX_LIMITED?
The last I heard from Gerald they were still mildly interested in
keeping the dccssblk dax support going with this limited mode, and
threatened to add full page support at a later date:
---
From: Gerald
dcssblk seems to work fine, I did not see any SIGBUS while "executing
in place" from dcssblk with the current upstream kernel, maybe because
we only use dcssblk with fs dax in read-only mode.
Anyway, the dcssblk change is fine with me. I will look into adding
struct pages for dcssblk memory later, to make it work again with
this change, but for now I do not know of anyone needing this in the
upstream kernel.
https://www.spinics.net/lists/linux-xfs/msg14628.html
---
> +void generic_dax_pagefree(struct page *page, void *data)
> +{
> + wake_up_var(&page->_refcount);
> +}
> +EXPORT_SYMBOL_GPL(generic_dax_pagefree);
Why is this here and exported instead of static in drivers/nvdimm/pmem.c?
I was thinking it did not belong to the pmem driver, but you're right
unless / until we grow another fsdax capable driver this detail can
stay internal to the pmem driver.