Re: [MINI-OS PATCH v2 1/2] 9pfs: add fstat file operation hook

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Jan Beulich, le lun. 24 mars 2025 11:21:48 +0100, a ecrit:
> On 23.03.2025 15:57, Jürgen Groß wrote:
> > On 23.03.25 01:01, Samuel Thibault wrote:
> >> Juergen Gross, le ven. 21 mars 2025 10:31:44 +0100, a ecrit:
> >>> Add a file operations fstat hook to the 9pfs frontend.
> >>>
> >>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> >>> Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> >>> ---
> >>> V2:
> >>> - or file access mode into st_mode (Jason Andryuk)
> >>> ---
> >>>   9pfront.c | 29 +++++++++++++++++++++++++++++
> >>>   1 file changed, 29 insertions(+)
> >>>
> >>> diff --git a/9pfront.c b/9pfront.c
> >>> index 1741d600..7257a07e 100644
> >>> --- a/9pfront.c
> >>> +++ b/9pfront.c
> >>> @@ -85,6 +85,8 @@ struct file_9pfs {
> >>>   
> >>>   #define P9_QID_SIZE    13
> >>>   
> >>> +#define QID_TYPE_DIR   0x80     /* Applies to qid[0]. */
> >>> +
> >>>   struct p9_header {
> >>>       uint32_t size;
> >>>       uint8_t cmd;
> >>> @@ -950,6 +952,32 @@ static int write_9pfs(struct file *file, const void 
> >>> *buf, size_t nbytes)
> >>>       return ret;
> >>>   }
> >>>   
> >>> +static int fstat_9pfs(struct file *file, struct stat *buf)
> >>> +{
> >>> +    struct file_9pfs *f9pfs = file->filedata;
> >>> +    struct p9_stat stat;
> >>> +    int ret;
> >>> +
> >>> +    ret = p9_stat(f9pfs->dev, f9pfs->fid, &stat);
> >>> +    if ( ret )
> >>> +    {
> >>> +        errno = EIO;
> >>> +        return -1;
> >>> +    }
> >>> +
> >>> +    buf->st_mode = (stat.qid[0] == QID_TYPE_DIR) ? S_IFDIR : S_IFREG;
> >>> +    buf->st_mode |= stat.mode & 0777;
> >>> +    buf->st_atime = stat.atime;
> >>> +    buf->st_mtime = stat.mtime;
> >>
> >> Should we perhaps also fill st_ctime? Leaving it at 0 could surprise
> >> other software layers.
> > 
> > I can set it to the same value as st_mtime.
> 
> Maybe the smaller of atime and mtime?

That'd be better, yes.

Samuel