svn commit: r322198 - in head: share/man/man9 sys/geom
Nathan Whitehorn
nwhitehorn at freebsd.org
Mon Aug 7 21:29:29 UTC 2017
It would be really nice to let gpart provide aliases correct to
partition labels, which would fix the existing racy and unreliable
glabel code. Do you see any obstacles to using this code for that?
-Nathan
On 08/07/17 14:12, Warner Losh wrote:
> Author: imp
> Date: Mon Aug 7 21:12:38 2017
> New Revision: 322198
> URL: https://svnweb.freebsd.org/changeset/base/322198
>
> Log:
> Expose API to allow disks to ask for alias names in devfs.
>
> Implement disk_add_alias to allow aliases to be added to disks. All
> disk have a primary name (say "foo") can also have secondary names
> (say "bar") such that all instances of "foo" also have a "bar"
> alias. So if you have foo0, foo0p1, foo1, foo1s1 and foo1s1a nodes
> created by the foo driver and gpart, device nodes bar0, bar0p1, bar1,
> bar1s1 and bar1s1a will appear as symlinks back to the original nodes.
> This generalizes to multiple aliases. However, since the unit number
> follows the primary name, multiple device drivers can't create the
> same aliases unless those drives coorinate the unit number space (eg
> you couldn't add an alias 'disk' to both 'da' and 'ada' because it's
> possible to have da0 and ada0, because 'disk0' is ambiguous).
>
> Differential Revision: https://reviews.freebsd.org/D11873
>
> Modified:
> head/share/man/man9/disk.9
> head/sys/geom/geom_disk.c
> head/sys/geom/geom_disk.h
>
> Modified: head/share/man/man9/disk.9
> ==============================================================================
> --- head/share/man/man9/disk.9 Mon Aug 7 21:12:33 2017 (r322197)
> +++ head/share/man/man9/disk.9 Mon Aug 7 21:12:38 2017 (r322198)
> @@ -27,7 +27,7 @@
> .\"
> .\" $FreeBSD$
> .\"
> -.Dd October 30, 2012
> +.Dd August 3, 2017
> .Dt DISK 9
> .Os
> .Sh NAME
> @@ -45,6 +45,8 @@
> .Fn disk_destroy "struct disk *disk"
> .Ft int
> .Fn disk_resize "struct disk *disk" "int flags"
> +.Ft void
> +.Fn disk_add_alias "struct disk *disk" "const char *alias"
> .Sh DESCRIPTION
> The disk storage API permits kernel device drivers providing access to
> disk-like storage devices to advertise the device to other kernel
> @@ -69,6 +71,20 @@ function,
> fill in the fields and call
> .Fn disk_create
> when the device is ready to service requests.
> +.Fn disk_add_alias
> +adds an alias for the disk and must be called before
> +.Fn disk_create ,
> +but may be called multiple times.
> +For each alias added, a device node will be created with
> +.Xr make_dev_alias 9
> +in the same way primary device nodes are created with
> +.Xr make_dev 9
> +for
> +.Va d_name
> +and
> +.Va d_unit .
> +Care should be taken to ensure that only one driver creates aliases
> +for any given name.
> .Fn disk_resize
> can be called by the driver after modifying
> .Va d_mediasize
> @@ -227,7 +243,13 @@ structure for this disk device.
> .El
> .Sh SEE ALSO
> .Xr GEOM 4 ,
> -.Xr devfs 5
> +.Xr devfs 5 ,
> +.Xr MAKE_DEV 9
> .Sh AUTHORS
> This manual page was written by
> .An Robert Watson .
> +.Sh BUGS
> +Disk aliases are not a general purpose aliasing mechanism, but are
> +intended only to ease the transition from one name to another.
> +They can be used to ensure that nvd0 and nda0 are the same thing.
> +They cannot be used to implement the diskX concept from macOS.
>
> Modified: head/sys/geom/geom_disk.c
> ==============================================================================
> --- head/sys/geom/geom_disk.c Mon Aug 7 21:12:33 2017 (r322197)
> +++ head/sys/geom/geom_disk.c Mon Aug 7 21:12:38 2017 (r322198)
> @@ -676,6 +676,7 @@ g_disk_create(void *arg, int flag)
> struct g_provider *pp;
> struct disk *dp;
> struct g_disk_softc *sc;
> + struct disk_alias *dap;
> char tmpstr[80];
>
> if (flag == EV_CANCEL)
> @@ -704,6 +705,10 @@ g_disk_create(void *arg, int flag)
> sc->dp = dp;
> gp = g_new_geomf(&g_disk_class, "%s%d", dp->d_name, dp->d_unit);
> gp->softc = sc;
> + LIST_FOREACH(dap, &dp->d_aliases, da_next) {
> + snprintf(tmpstr, sizeof(tmpstr), "%s%d", dap->da_alias, dp->d_unit);
> + g_geom_add_alias(gp, tmpstr);
> + }
> pp = g_new_providerf(gp, "%s", gp->name);
> devstat_remove_entry(pp->stat);
> pp->stat = NULL;
> @@ -791,6 +796,7 @@ g_disk_destroy(void *ptr, int flag)
> struct disk *dp;
> struct g_geom *gp;
> struct g_disk_softc *sc;
> + struct disk_alias *dap, *daptmp;
>
> g_topology_assert();
> dp = ptr;
> @@ -802,6 +808,8 @@ g_disk_destroy(void *ptr, int flag)
> dp->d_geom = NULL;
> g_wither_geom(gp, ENXIO);
> }
> + LIST_FOREACH_SAFE(dap, &dp->d_aliases, da_next, daptmp)
> + g_free(dap);
>
> g_free(dp);
> }
> @@ -834,8 +842,11 @@ g_disk_ident_adjust(char *ident, size_t size)
> struct disk *
> disk_alloc(void)
> {
> + struct disk *dp;
>
> - return (g_malloc(sizeof(struct disk), M_WAITOK | M_ZERO));
> + dp = g_malloc(sizeof(struct disk), M_WAITOK | M_ZERO);
> + LIST_INIT(&dp->d_aliases);
> + return (dp);
> }
>
> void
> @@ -882,6 +893,18 @@ disk_destroy(struct disk *dp)
> if (dp->d_devstat != NULL)
> devstat_remove_entry(dp->d_devstat);
> g_post_event(g_disk_destroy, dp, M_WAITOK, NULL);
> +}
> +
> +void
> +disk_add_alias(struct disk *dp, const char *name)
> +{
> + struct disk_alias *dap;
> +
> + dap = (struct disk_alias *)g_malloc(
> + sizeof(struct disk_alias) + strlen(name) + 1, M_WAITOK);
> + strcpy((char *)(dap + 1), name);
> + dap->da_alias = (const char *)(dap + 1);
> + LIST_INSERT_HEAD(&dp->d_aliases, dap, da_next);
> }
>
> void
>
> Modified: head/sys/geom/geom_disk.h
> ==============================================================================
> --- head/sys/geom/geom_disk.h Mon Aug 7 21:12:33 2017 (r322197)
> +++ head/sys/geom/geom_disk.h Mon Aug 7 21:12:38 2017 (r322198)
> @@ -66,6 +66,11 @@ typedef enum {
> DISK_INIT_DONE
> } disk_init_level;
>
> +struct disk_alias {
> + LIST_ENTRY(disk_alias) da_next;
> + const char *da_alias;
> +};
> +
> struct disk {
> /* Fields which are private to geom_disk */
> struct g_geom *d_geom;
> @@ -109,6 +114,9 @@ struct disk {
>
> /* Fields private to the driver */
> void *d_drv1;
> +
> + /* Fields private to geom_disk, to be moved on next version bump */
> + LIST_HEAD(,disk_alias) d_aliases;
> };
>
> #define DISKFLAG_RESERVED 0x1 /* Was NEEDSGIANT */
> @@ -132,6 +140,7 @@ void disk_attr_changed(struct disk *dp, const char *at
> void disk_media_changed(struct disk *dp, int flag);
> void disk_media_gone(struct disk *dp, int flag);
> int disk_resize(struct disk *dp, int flag);
> +void disk_add_alias(struct disk *disk, const char *);
>
> #define DISK_VERSION_00 0x58561059
> #define DISK_VERSION_01 0x5856105a
>
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