On 3/9/26 10:53, Ackerley Tng wrote: > The guest memfd currently does not update the inode's i_blocks and i_bytes > count when memory is allocated or freed. Hence, st_blocks returned from > fstat() is always 0. > > Introduce byte accounting for guest memfd inodes. When a new folio is > added to the filemap, add the folio's size. Use the .invalidate_folio() > callback to subtract the folio's size from inode fields when folios are > truncated and removed from the filemap. > > Signed-off-by: Ackerley Tng <[email protected]> > --- > virt/kvm/guest_memfd.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index 462c5c5cb602a..77219551056a7 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -136,6 +136,9 @@ static struct folio *kvm_gmem_get_folio(struct inode > *inode, pgoff_t index) > mapping_gfp_mask(inode->i_mapping), > policy); > mpol_cond_put(policy); > > + if (!IS_ERR(folio)) > + inode_add_bytes(inode, folio_size(folio)); > +
Can't we have two concurrent calls to __filemap_get_folio_mpol(), and we don't really know whether our call allocated the folio or simply found one (the other caller allocated) in the pagecache? -- Cheers, David
