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Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Shuah Khan , Jonathan Corbet , Alexander Viro , Christian Brauner , Jan Kara , seanjc@google.com, rientjes@google.com, rick.p.edgecombe@intel.com, yan.y.zhao@intel.com, fvdl@google.com, jthoughton@google.com, vannapurve@google.com, shivankg@amd.com, michael.roth@amd.com, pratyush@kernel.org, pasha.tatashin@soleen.com, kalyazin@amazon.com, tabba@google.com, Vlastimil Babka Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Ackerley Tng Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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 --- 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 *i= node, pgoff_t index) mapping_gfp_mask(inode->i_mapping), policy); mpol_cond_put(policy); =20 + if (!IS_ERR(folio)) + inode_add_bytes(inode, folio_size(folio)); + /* * External interfaces like kvm_gmem_get_pfn() support dealing * with hugepages to a degree, but internally, guest_memfd currently @@ -532,10 +535,21 @@ static void kvm_gmem_free_folio(struct folio *folio) } #endif =20 +static void kvm_gmem_invalidate_folio(struct folio *folio, size_t offset, = size_t len) +{ + size_t bytes =3D folio_size(folio); + + WARN_ON_ONCE(offset); + WARN_ON_ONCE(len !=3D bytes); + + inode_sub_bytes(folio_inode(folio), bytes); +} + static const struct address_space_operations kvm_gmem_aops =3D { .dirty_folio =3D noop_dirty_folio, .migrate_folio =3D kvm_gmem_migrate_folio, .error_remove_folio =3D kvm_gmem_error_folio, + .invalidate_folio =3D kvm_gmem_invalidate_folio, #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE .free_folio =3D kvm_gmem_free_folio, #endif --=20 2.53.0.473.g4a7958ca14-goog