On Wed, Dec 14, 2022 at 12:35:24PM +1100, Dave Chinner wrote:
> On Tue, Dec 13, 2022 at 06:29:30PM +0100, Andrey Albershteyn wrote:
> > fs-verity will read and attach metadata (not the tree itself) from
> > a disk for those inodes which already have fs-verity enabled.
> >
> > Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx>
> > ---
> > fs/xfs/xfs_file.c | 8 ++++++++
> > fs/xfs/xfs_super.c | 2 ++
> > 2 files changed, 10 insertions(+)
> >
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index 242165580e682..5eadd9a37c50e 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -32,6 +32,7 @@
> > #include <linux/mman.h>
> > #include <linux/fadvise.h>
> > #include <linux/mount.h>
> > +#include <linux/fsverity.h>
> >
> > static const struct vm_operations_struct xfs_file_vm_ops;
> >
> > @@ -1170,9 +1171,16 @@ xfs_file_open(
> > struct inode *inode,
> > struct file *file)
> > {
> > + int error = 0;
> > +
> > if (xfs_is_shutdown(XFS_M(inode->i_sb)))
> > return -EIO;
> > file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC;
> > +
> > + error = fsverity_file_open(inode, file);
> > + if (error)
> > + return error;
>
> This is a hot path, so shouldn't we elide the function call
> altogether if verity is not enabled on the inode? i.e:
>
> if (IS_VERITY(inode)) {
> error = fsverity_file_open(inode, file);
> if (error)
> return error;
> }
>
> It doesn't really matter for a single file open, but when you're
> opening a few million inodes every second the function call overhead
> only to immediately return because IS_VERITY() is false adds up...
>
> > return generic_file_open(inode, file);
> > }
> >
> > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> > index 8f1e9b9ed35d9..50c2c819ba940 100644
> > --- a/fs/xfs/xfs_super.c
> > +++ b/fs/xfs/xfs_super.c
> > @@ -45,6 +45,7 @@
> > #include <linux/magic.h>
> > #include <linux/fs_context.h>
> > #include <linux/fs_parser.h>
> > +#include <linux/fsverity.h>
> >
> > static const struct super_operations xfs_super_operations;
> >
> > @@ -647,6 +648,7 @@ xfs_fs_destroy_inode(
> > ASSERT(!rwsem_is_locked(&inode->i_rwsem));
> > XFS_STATS_INC(ip->i_mount, vn_rele);
> > XFS_STATS_INC(ip->i_mount, vn_remove);
> > + fsverity_cleanup_inode(inode);
>
> Similarly, shouldn't this be:
>
> if (fsverity_active(inode))
> fsverity_cleanup_inode(inode);
>
If you actually want to do that, then we should instead make these functions
inline functions that do the "is anything needed?" check, then call a
double-underscored version that does the actual work. Some of the fscrypt
functions are like that. Then all filesystems would get the benefit.
Funnily enough, I had actually wanted to do that for fsverity_file_open()
originally, but Ted had preferred the simpler version.
Anyway, if this is something you want, I can change it to be that way.
- Eric
