Re: [PATCH 4/4] 9pfs: Introduce futimens file op

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Monday, March 10, 2025 6:11:01 PM CET Greg Kurz wrote:
> Add an futimens operation to the fs driver and use if when a fid has
> a valid file descriptor. This is required to support more cases where
> the client wants to do an action on an unlinked file which it still
> has an open file decriptor for.
> 
> Only 9P2000.L was considered.
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  fsdev/file-op-9p.h |  2 ++
>  hw/9pfs/9p-local.c |  9 +++++++++
>  hw/9pfs/9p-synth.c |  8 ++++++++
>  hw/9pfs/9p-util.h  |  1 +
>  hw/9pfs/9p.c       |  6 +++++-
>  hw/9pfs/cofs.c     | 19 +++++++++++++++++++
>  hw/9pfs/coth.h     |  2 ++
>  7 files changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
> index 40a40f7d8af8..ee65f4ffad2f 100644
> --- a/fsdev/file-op-9p.h
> +++ b/fsdev/file-op-9p.h
> @@ -167,6 +167,8 @@ struct FileOperations {
>      bool (*has_valid_handle)(int fid_type, V9fsFidOpenState *fs);
>      int (*ftruncate)(FsContext *ctx, int fid_type, V9fsFidOpenState *fs,
>                       off_t size);
> +    int (*futimens)(FsContext *ctx, int fid_type, V9fsFidOpenState *fs,
> +                    const struct timespec *times);
>  };
>  
>  #endif
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index fa763b0662f5..f8b932802c17 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -1104,6 +1104,14 @@ out:
>      return ret;
>  }
>  
> +static int local_futimens(FsContext *s, int fid_type, V9fsFidOpenState *fs,
> +                          const struct timespec *times)
> +{
> +    int fd = local_fid_fd(fid_type, fs);
> +
> +    return qemu_futimens(fd, times);
> +}
> +
>  static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name,
>                                   int flags)
>  {
> @@ -1628,4 +1636,5 @@ FileOperations local_ops = {
>      .unlinkat = local_unlinkat,
>      .has_valid_handle = local_has_valid_handle,
>      .ftruncate = local_ftruncate,
> +    .futimens = local_futimens,
>  };
> diff --git a/hw/9pfs/9p-synth.c b/hw/9pfs/9p-synth.c
> index 7f0e13f0ddd8..3bf4bb17e767 100644
> --- a/hw/9pfs/9p-synth.c
> +++ b/hw/9pfs/9p-synth.c
> @@ -424,6 +424,13 @@ static int synth_utimensat(FsContext *fs_ctx, V9fsPath *path,
>      return 0;
>  }
>  
> +static int synth_futimens(FsContext *fs_ctx, int fid_type, V9fsFidOpenState *fs,
> +                          const struct timespec *buf)
> +{
> +    errno = ENOSYS;
> +    return -1;
> +}
> +
>  static int synth_remove(FsContext *ctx, const char *path)
>  {
>      errno = EPERM;
> @@ -664,4 +671,5 @@ FileOperations synth_ops = {
>      .unlinkat     = synth_unlinkat,
>      .has_valid_handle = synth_has_valid_handle,
>      .ftruncate    = synth_ftruncate,
> +    .futimens     = synth_futimens,
>  };
> diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h
> index 7bc4ec8e85cc..a1924fe3f05a 100644
> --- a/hw/9pfs/9p-util.h
> +++ b/hw/9pfs/9p-util.h
> @@ -103,6 +103,7 @@ static inline int errno_to_dotl(int err) {
>  #define qemu_renameat   renameat
>  #define qemu_utimensat  utimensat
>  #define qemu_unlinkat   unlinkat
> +#define qemu_futimens   futimens
>  
>  static inline void close_preserve_errno(int fd)
>  {
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 35b2ed900a01..8024cc06a090 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1708,7 +1708,11 @@ static void coroutine_fn v9fs_setattr(void *opaque)
>          } else {
>              times[1].tv_nsec = UTIME_OMIT;
>          }
> -        err = v9fs_co_utimensat(pdu, &fidp->path, times);
> +        if (fid_has_valid_handle(pdu->s, fidp)) {
> +            err = v9fs_co_futimens(pdu, fidp, times);
> +        } else {
> +            err = v9fs_co_utimensat(pdu, &fidp->path, times);
> +        }
>          if (err < 0) {
>              goto out;
>          }
> diff --git a/hw/9pfs/cofs.c b/hw/9pfs/cofs.c
> index 893466fb1a44..12fa8c9fe9cd 100644
> --- a/hw/9pfs/cofs.c
> +++ b/hw/9pfs/cofs.c
> @@ -139,6 +139,25 @@ int coroutine_fn v9fs_co_utimensat(V9fsPDU *pdu, V9fsPath *path,
>      return err;
>  }
>  
> +int coroutine_fn v9fs_co_futimens(V9fsPDU *pdu, V9fsFidState *fidp,
> +                                  struct timespec times[2])
> +{
> +    int err;
> +    V9fsState *s = pdu->s;
> +
> +    if (v9fs_request_cancelled(pdu)) {
> +        return -EINTR;
> +    }
> +    v9fs_co_run_in_worker(
> +        {
> +            err = s->ops->futimens(&s->ctx, fidp->fid_type, &fidp->fs, times);
> +            if (err < 0) {
> +                err = -errno;
> +            }
> +        });
> +    return err;
> +}
> +
>  int coroutine_fn v9fs_co_chown(V9fsPDU *pdu, V9fsPath *path, uid_t uid,
>                                 gid_t gid)
>  {
> diff --git a/hw/9pfs/coth.h b/hw/9pfs/coth.h
> index 0b8ee4c56495..9920f98129e9 100644
> --- a/hw/9pfs/coth.h
> +++ b/hw/9pfs/coth.h
> @@ -111,5 +111,7 @@ int coroutine_fn v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t,
>                                  V9fsStatDotl *v9stat);
>  int coroutine_fn v9fs_co_ftruncate(V9fsPDU *pdu, V9fsFidState *fidp,
>                                     off_t size);
> +int coroutine_fn v9fs_co_futimens(V9fsPDU *pdu, V9fsFidState *fidp,
> +                                  struct timespec times[2]);
>  
>  #endif

Same nit as with previous patch: I would group v9fs_co_futimens() and
v9fs_co_utimensat() together in this header file for overview reason.

Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

/Christian