On Monday, March 10, 2025 6:11:00 PM CET Greg Kurz wrote:
> Add an ftruncate 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 <gr...@kaod.org>
> ---
> fsdev/file-op-9p.h | 2 ++
> hw/9pfs/9p-local.c | 9 +++++++++
> hw/9pfs/9p-synth.c | 8 ++++++++
> hw/9pfs/9p.c | 6 +++++-
> hw/9pfs/cofs.c | 18 ++++++++++++++++++
> hw/9pfs/coth.h | 2 ++
> 6 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
> index 39fee185f4ce..40a40f7d8af8 100644
> --- a/fsdev/file-op-9p.h
> +++ b/fsdev/file-op-9p.h
> @@ -165,6 +165,8 @@ struct FileOperations {
> V9fsPath *newdir, const char *new_name);
> int (*unlinkat)(FsContext *ctx, V9fsPath *dir, const char *name, int
> flags);
> bool (*has_valid_handle)(int fid_type, V9fsFidOpenState *fs);
> + int (*ftruncate)(FsContext *ctx, int fid_type, V9fsFidOpenState *fs,
> + off_t size);
> };
>
> #endif
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index 03e5304ef888..fa763b0662f5 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -1046,6 +1046,14 @@ static int local_truncate(FsContext *ctx, V9fsPath
> *fs_path, off_t size)
> return ret;
> }
>
> +static int local_ftruncate(FsContext *ctx, int fid_type, V9fsFidOpenState
> *fs,
> + off_t size)
> +{
> + int fd = local_fid_fd(fid_type, fs);
> +
> + return ftruncate(fd, size);
> +}
> +
> static int local_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
> {
> char *dirpath = g_path_get_dirname(fs_path->data);
> @@ -1619,4 +1627,5 @@ FileOperations local_ops = {
> .renameat = local_renameat,
> .unlinkat = local_unlinkat,
> .has_valid_handle = local_has_valid_handle,
> + .ftruncate = local_ftruncate,
> };
> diff --git a/hw/9pfs/9p-synth.c b/hw/9pfs/9p-synth.c
> index fa0b187a1b80..7f0e13f0ddd8 100644
> --- a/hw/9pfs/9p-synth.c
> +++ b/hw/9pfs/9p-synth.c
> @@ -356,6 +356,13 @@ static int synth_truncate(FsContext *ctx, V9fsPath
> *path, off_t offset)
> return -1;
> }
>
> +static int synth_ftruncate(FsContext *ctx, int fid_type, V9fsFidOpenState
> *fs,
> + off_t size)
> +{
> + errno = ENOSYS;
> + return -1;
> +}
> +
> static int synth_chmod(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
> {
> errno = EPERM;
> @@ -656,4 +663,5 @@ FileOperations synth_ops = {
> .renameat = synth_renameat,
> .unlinkat = synth_unlinkat,
> .has_valid_handle = synth_has_valid_handle,
> + .ftruncate = synth_ftruncate,
> };
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 969fb2f8c494..35b2ed900a01 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1733,7 +1733,11 @@ static void coroutine_fn v9fs_setattr(void *opaque)
> }
> }
> if (v9iattr.valid & (P9_ATTR_SIZE)) {
> - err = v9fs_co_truncate(pdu, &fidp->path, v9iattr.size);
> + if (fid_has_valid_handle(pdu->s, fidp)) {
> + err = v9fs_co_ftruncate(pdu, fidp, v9iattr.size);
> + } else {
> + err = v9fs_co_truncate(pdu, &fidp->path, v9iattr.size);
> + }
> if (err < 0) {
> goto out;
> }
> diff --git a/hw/9pfs/cofs.c b/hw/9pfs/cofs.c
> index 67e3ae5c5ccd..893466fb1a44 100644
> --- a/hw/9pfs/cofs.c
> +++ b/hw/9pfs/cofs.c
> @@ -184,6 +184,24 @@ int coroutine_fn v9fs_co_truncate(V9fsPDU *pdu, V9fsPath
> *path, off_t size)
> return err;
> }
>
> +int coroutine_fn v9fs_co_ftruncate(V9fsPDU *pdu, V9fsFidState *fidp, off_t
> size)
> +{
> + int err;
> + V9fsState *s = pdu->s;
> +
> + if (v9fs_request_cancelled(pdu)) {
> + return -EINTR;
> + }
> + v9fs_co_run_in_worker(
> + {
> + err = s->ops->ftruncate(&s->ctx, fidp->fid_type, &fidp->fs,
> size);
> + if (err < 0) {
> + err = -errno;
> + }
> + });
> + return err;
> +}
> +
> int coroutine_fn v9fs_co_mknod(V9fsPDU *pdu, V9fsFidState *fidp,
> V9fsString *name, uid_t uid, gid_t gid,
> dev_t dev, mode_t mode, struct stat *stbuf)
> diff --git a/hw/9pfs/coth.h b/hw/9pfs/coth.h
> index 2c54249b3577..0b8ee4c56495 100644
> --- a/hw/9pfs/coth.h
> +++ b/hw/9pfs/coth.h
> @@ -109,5 +109,7 @@ int coroutine_fn v9fs_co_name_to_path(V9fsPDU *, V9fsPath
> *,
> const char *, V9fsPath *);
> 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);
>
> #endif
Nit: I would move v9fs_co_ftruncate() close to v9fs_co_truncate() to make it
easier preserving the overview on this header file.
Rest looks fine:
Reviewed-by: Christian Schoenebeck <qemu_...@crudebyte.com>
/Christian
