Date: Fri, 11 Oct 2019 11:28:38 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Zhichao1.Li@dell.com Cc: freebsd-fs@freebsd.org, freebsd-drivers@freebsd.org, Shunchao.Hu@dell.com Subject: Re: a issue about getting a devfs node's fullpath Message-ID: <20191011082838.GR44691@kib.kiev.ua> In-Reply-To: <54b7173c96df43689de04f848ca86de6@KULX13MDC103.APAC.DELL.COM> References: <c6d34bd0b4114bee956b0af6d680a67f@KULX13MDC103.APAC.DELL.COM> <20191010153932.GO44691@kib.kiev.ua> <54b7173c96df43689de04f848ca86de6@KULX13MDC103.APAC.DELL.COM>
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On Fri, Oct 11, 2019 at 02:23:14AM +0000, Zhichao1.Li@dell.com wrote:
> Hello
> Thank you for your time
> Unfortunately it does not work, how about this way?
It does not work in which way ? I tried it and it worked as expected.
Your patch is wrong, VOP_VPTOCNP() must return parent vnode, if any.
>
> --- a/src/sys/fs/devfs/devfs_vnops.c
> +++ b/src/sys/fs/devfs/devfs_vnops.c
> @@ -293,7 +293,14 @@ devfs_vptocnp(struct vop_vptocnp_args *ap)
> }
> bcopy(dd->de_cdp->cdp_c.si_name, buf + i,
> strlen(dd->de_cdp->cdp_c.si_name));
> - de = dd->de_dir;
> + /*
> + * when dealing with VCHR
> + * the element 'si_name' already
> + * holds the full path string
> + * except rootdir, so just go
> + * to the rootdir
> + */
> + de = dmp->dm_rootdir;
> } else if (vp->v_type == VDIR) {
> if (dd == dmp->dm_rootdir) {
> *dvp = vp;
> @@ -307,13 +314,17 @@ devfs_vptocnp(struct vop_vptocnp_args *ap)
> }
> bcopy(dd->de_dirent->d_name, buf + i,
> dd->de_dirent->d_namlen);
> - de = dd;
> + /*
> + * when dealing with VDIR
> + * get its parent
> + */
> + de = devfs_parent_dirent(dd);
> } else {
> error = ENOENT;
> goto finished;
> }
> *buflen = i;
> - de = devfs_parent_dirent(de);
> + /*no need to get another parent*/
> if (de == NULL) {
> error = ENOENT;
> goto finished;
>
> another thing is this func is called by many modules, I want to ensure modifying the func this way will not impact other modules and not bring some bugs, would you be so kind to help me out?
>
> thank you
>
> -----Original Message-----
> From: Konstantin Belousov <kib@freebsd.org>
> Sent: Thursday, October 10, 2019 11:40 PM
> To: Li, Zhichao1 <Zhichao_Li1@Dell.com>
> Cc: freebsd-fs@freebsd.org; freebsd-drivers@freebsd.org; Hu, Shunchao <Shunchao_Hu@Dell.com>
> Subject: Re: a issue about getting a devfs node's fullpath
>
>
> [EXTERNAL EMAIL]
>
> On Thu, Oct 10, 2019 at 05:49:55AM +0000, Zhichao1.Li@dell.com wrote:
> > Dear freebsd developers
> > I know you're swamped, so I'll be brief.
> > I am trying to get a node's full under /dev by calling the function 'vn_fullpath', when dealing with things like '/dev/null' or '/dev/usb/1.0.1', it works well.
> > However when dealing a node under more than 2 sub directories (e.g. /dev/bus/usb/001/002) which I made by calling 'make_dev_s' , it goes a little bit different, I got a string "/dev/bus/usb/bus/usb/001/002"
> > And I found the function 'devfs_vptocnp' gets the string wrongly when
> > dealing multi slashes path string, I have remark the code as followed and put some comments would you please take a look, and tell me what the purpose this func pass the string that way?
>
> Try this. Not tested.
>
> diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c index 3b80c68e309..f20b466d88b 100644
> --- a/sys/fs/devfs/devfs_vnops.c
> +++ b/sys/fs/devfs/devfs_vnops.c
> @@ -284,38 +284,27 @@ devfs_vptocnp(struct vop_vptocnp_args *ap)
> if (error != 0)
> return (error);
>
> - i = *buflen;
> + if (vp->v_type != VCHR && vp->v_type != VDIR) {
> + error = ENOENT;
> + goto finished;
> + }
> +
> dd = vp->v_data;
> + if (vp->v_type == VDIR && dd == dmp->dm_rootdir) {
> + *dvp = vp;
> + vref(*dvp);
> + goto finished;
> + }
>
> - if (vp->v_type == VCHR) {
> - i -= strlen(dd->de_cdp->cdp_c.si_name);
> - if (i < 0) {
> - error = ENOMEM;
> - goto finished;
> - }
> - bcopy(dd->de_cdp->cdp_c.si_name, buf + i,
> - strlen(dd->de_cdp->cdp_c.si_name));
> - de = dd->de_dir;
> - } else if (vp->v_type == VDIR) {
> - if (dd == dmp->dm_rootdir) {
> - *dvp = vp;
> - vref(*dvp);
> - goto finished;
> - }
> - i -= dd->de_dirent->d_namlen;
> - if (i < 0) {
> - error = ENOMEM;
> - goto finished;
> - }
> - bcopy(dd->de_dirent->d_name, buf + i,
> - dd->de_dirent->d_namlen);
> - de = dd;
> - } else {
> - error = ENOENT;
> + i = *buflen;
> + i -= dd->de_dirent->d_namlen;
> + if (i < 0) {
> + error = ENOMEM;
> goto finished;
> }
> + bcopy(dd->de_dirent->d_name, buf + i, dd->de_dirent->d_namlen);
> *buflen = i;
> - de = devfs_parent_dirent(de);
> + de = devfs_parent_dirent(dd);
> if (de == NULL) {
> error = ENOENT;
> goto finished;
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