On mercoledì 6 luglio 2022 12:38:29 CEST Fabio M. De Francesco wrote:
> On martedì 5 luglio 2022 21:04:04 CEST Ira Weiny wrote:
> > On Mon, Jul 04, 2022 at 05:23:22PM +0200, Fabio M. De Francesco wrote:
> > > The use of kmap() is being deprecated in favor of kmap_local_page().
> With
> > > kmap_local_page(), the mapping is per thread, CPU local and not
> globally
> > > visible.
> > >
> > > Therefore, use kmap_local_page() / kunmap_local() in zstd.c because
in
> this
> > > file the mappings are per thread and are not visible in other
contexts.
> In
> > > the meanwhile use plain page_address() on pages allocated with the
> GFP_NOFS
> > > flag instead of calling kmap*() on them (since they are always
> allocated
> > > from ZONE_NORMAL).
> > >
> > > Tested with xfstests on QEMU + KVM 32 bits VM with 4GB of RAM and
> > > booting a kernel with HIGHMEM64G enabled.
> > >
> > > Cc: Filipe Manana <fdmanana@xxxxxxxxxx>
> > > Suggested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> > > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx>
> > > ---
> > > fs/btrfs/zstd.c | 34 ++++++++++++++--------------------
> > > 1 file changed, 14 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
> > > index 0fe31a6f6e68..78e0272e770e 100644
> > > --- a/fs/btrfs/zstd.c
> > > +++ b/fs/btrfs/zstd.c
> > > @@ -403,7 +403,7 @@ int zstd_compress_pages(struct list_head *ws,
> struct address_space *mapping,
> > >
> > > /* map in the first page of input data */
> > > in_page = find_get_page(mapping, start >> PAGE_SHIFT);
> > > - workspace->in_buf.src = kmap(in_page);
> > > + workspace->in_buf.src = kmap_local_page(in_page);
> > > workspace->in_buf.pos = 0;
> > > workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
> > >
> > > @@ -415,7 +415,7 @@ int zstd_compress_pages(struct list_head *ws,
> struct address_space *mapping,
> > > goto out;
> > > }
> > > pages[nr_pages++] = out_page;
> > > - workspace->out_buf.dst = kmap(out_page);
> > > + workspace->out_buf.dst = page_address(out_page);
> > > workspace->out_buf.pos = 0;
> > > workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
> > >
> > > @@ -450,9 +450,7 @@ int zstd_compress_pages(struct list_head *ws,
> struct address_space *mapping,
> > > if (workspace->out_buf.pos == workspace->out_buf.size)
> {
> > > tot_out += PAGE_SIZE;
> > > max_out -= PAGE_SIZE;
> > > - kunmap(out_page);
> > > if (nr_pages == nr_dest_pages) {
> > > - out_page = NULL;
> > > ret = -E2BIG;
> > > goto out;
> > > }
> > > @@ -462,7 +460,7 @@ int zstd_compress_pages(struct list_head *ws,
> struct address_space *mapping,
> > > goto out;
> > > }
> > > pages[nr_pages++] = out_page;
> > > - workspace->out_buf.dst = kmap(out_page);
> > > + workspace->out_buf.dst =
> page_address(out_page);
> > > workspace->out_buf.pos = 0;
> > > workspace->out_buf.size = min_t(size_t,
> max_out,
> > >
> PAGE_SIZE);
> > > @@ -477,15 +475,15 @@ int zstd_compress_pages(struct list_head *ws,
> struct address_space *mapping,
> > > /* Check if we need more input */
> > > if (workspace->in_buf.pos == workspace->in_buf.size) {
> > > tot_in += PAGE_SIZE;
> > > - kunmap(in_page);
> > > + kunmap_local(workspace->in_buf.src);
> > > put_page(in_page);
> > > -
> > > start += PAGE_SIZE;
> > > len -= PAGE_SIZE;
> > > in_page = find_get_page(mapping, start >>
> PAGE_SHIFT);
> > > - workspace->in_buf.src = kmap(in_page);
> > > + workspace->in_buf.src =
> kmap_local_page(in_page);
> > > workspace->in_buf.pos = 0;
> > > workspace->in_buf.size = min_t(size_t, len,
> PAGE_SIZE);
> > > + workspace->out_buf.dst =
> page_address(out_page);
> >
> > Why is this needed?
>
> Sorry. This initialization is not needed at all.
> Probably made a mistake with copy-pasting snippets of code.
>
> I'm going to send ASAP the fifth version of this series.
"fifth" -> "sixth".
>
> > The rest looks good,
>
> Thanks,
>
> Fabio
>
> > Ira
> >
> > [snip]
> >
>
>
>
>
