| Message ID | 20220503221728.185449-2-david@fromorbit.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | xfs: intent whiteouts | expand |
On Wed, May 04, 2022 at 08:17:19AM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > When we first allocate or resize an inline inode fork, we round up > the allocation to 4 byte alingment to make journal alignment > constraints. We don't clear the unused bytes, so we can copy up to > three uninitialised bytes into the journal. Zero those bytes so we > only ever copy zeros into the journal. > > Signed-off-by: Dave Chinner <dchinner@redhat.com> Yup. Thanks for the cleanup. Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > fs/xfs/libxfs/xfs_inode_fork.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c > index 9aee4a1e2fe9..a15ff38c3d41 100644 > --- a/fs/xfs/libxfs/xfs_inode_fork.c > +++ b/fs/xfs/libxfs/xfs_inode_fork.c > @@ -50,8 +50,13 @@ xfs_init_local_fork( > mem_size++; > > if (size) { > + /* > + * As we round up the allocation here, we need to ensure the > + * bytes we don't copy data into are zeroed because the log > + * vectors still copy them into the journal. > + */ > real_size = roundup(mem_size, 4); > - ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS); > + ifp->if_u1.if_data = kmem_zalloc(real_size, KM_NOFS); > memcpy(ifp->if_u1.if_data, data, size); > if (zero_terminate) > ifp->if_u1.if_data[size] = '\0'; > @@ -500,10 +505,11 @@ xfs_idata_realloc( > /* > * For inline data, the underlying buffer must be a multiple of 4 bytes > * in size so that it can be logged and stay on word boundaries. > - * We enforce that here. > + * We enforce that here, and use __GFP_ZERO to ensure that size > + * extensions always zero the unused roundup area. > */ > ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, roundup(new_size, 4), > - GFP_NOFS | __GFP_NOFAIL); > + GFP_NOFS | __GFP_NOFAIL | __GFP_ZERO); > ifp->if_bytes = new_size; > } > > -- > 2.35.1 >
On Wed, 2022-05-04 at 08:17 +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > When we first allocate or resize an inline inode fork, we round up > the allocation to 4 byte alingment to make journal alignment > constraints. We don't clear the unused bytes, so we can copy up to > three uninitialised bytes into the journal. Zero those bytes so we > only ever copy zeros into the journal. > > Signed-off-by: Dave Chinner <dchinner@redhat.com> Looks good Reviewed-by: Allison Henderson <allison.henderson@oracle.com> > --- > fs/xfs/libxfs/xfs_inode_fork.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_inode_fork.c > b/fs/xfs/libxfs/xfs_inode_fork.c > index 9aee4a1e2fe9..a15ff38c3d41 100644 > --- a/fs/xfs/libxfs/xfs_inode_fork.c > +++ b/fs/xfs/libxfs/xfs_inode_fork.c > @@ -50,8 +50,13 @@ xfs_init_local_fork( > mem_size++; > > if (size) { > + /* > + * As we round up the allocation here, we need to > ensure the > + * bytes we don't copy data into are zeroed because the > log > + * vectors still copy them into the journal. > + */ > real_size = roundup(mem_size, 4); > - ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS); > + ifp->if_u1.if_data = kmem_zalloc(real_size, KM_NOFS); > memcpy(ifp->if_u1.if_data, data, size); > if (zero_terminate) > ifp->if_u1.if_data[size] = '\0'; > @@ -500,10 +505,11 @@ xfs_idata_realloc( > /* > * For inline data, the underlying buffer must be a multiple of > 4 bytes > * in size so that it can be logged and stay on word > boundaries. > - * We enforce that here. > + * We enforce that here, and use __GFP_ZERO to ensure that size > + * extensions always zero the unused roundup area. > */ > ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, > roundup(new_size, 4), > - GFP_NOFS | __GFP_NOFAIL); > + GFP_NOFS | __GFP_NOFAIL | > __GFP_ZERO); > ifp->if_bytes = new_size; > } >
On Wed, May 04, 2022 at 08:17:19AM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > When we first allocate or resize an inline inode fork, we round up > the allocation to 4 byte alingment to make journal alignment > constraints. We don't clear the unused bytes, so we can copy up to > three uninitialised bytes into the journal. Zero those bytes so we > only ever copy zeros into the journal. It took me a while to figure out how GFP_ZERO works for krealloc, and it seems like kmalloc and friends always zero the entire length of the kmem_cache, so if krealloc reuses a rounded up allocation the padding is alredy zeroed at that point. So this looks good to me: Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c index 9aee4a1e2fe9..a15ff38c3d41 100644 --- a/fs/xfs/libxfs/xfs_inode_fork.c +++ b/fs/xfs/libxfs/xfs_inode_fork.c @@ -50,8 +50,13 @@ xfs_init_local_fork( mem_size++; if (size) { + /* + * As we round up the allocation here, we need to ensure the + * bytes we don't copy data into are zeroed because the log + * vectors still copy them into the journal. + */ real_size = roundup(mem_size, 4); - ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS); + ifp->if_u1.if_data = kmem_zalloc(real_size, KM_NOFS); memcpy(ifp->if_u1.if_data, data, size); if (zero_terminate) ifp->if_u1.if_data[size] = '\0'; @@ -500,10 +505,11 @@ xfs_idata_realloc( /* * For inline data, the underlying buffer must be a multiple of 4 bytes * in size so that it can be logged and stay on word boundaries. - * We enforce that here. + * We enforce that here, and use __GFP_ZERO to ensure that size + * extensions always zero the unused roundup area. */ ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, roundup(new_size, 4), - GFP_NOFS | __GFP_NOFAIL); + GFP_NOFS | __GFP_NOFAIL | __GFP_ZERO); ifp->if_bytes = new_size; }