G_PROVIDER(9)

✨ G_PROVIDER(9) ✨

okay so this is a page from the Kernel Developer's Manual, and it's all about managing GEOM providers — like, the whole g_new_providerf, g_destroy_provider, g_error_provider situation. bestie, let's get into it 💅

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🎀 NAME 🎀

g_new_providerf, g_destroy_provider, g_error_provider — GEOM providers management, aka keeping your logical disks in check ✨

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🌸 SYNOPSIS 🌸

#include <geom/geom.h>

struct g_provider *
g_new_providerf(struct g_geom *gp, const char *fmt, ...);

void
g_destroy_provider(struct g_provider *pp);

void
g_error_provider(struct g_provider *pp, int error);

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🦋 DESCRIPTION 🦋

So a GEOM provider is literally the front gate where a geom offers service 🫶. It's "a disk-like thing which appears in /dev" — a logical disk, in other words. Every provider has three main properties, no cap: name, sectorsize, and size. iconic.

g_new_providerf() — this one creates a new provider on the given geom gp. The name of the provider, which will show up as a device in devfs(4), gets built in a printf(3)-like way from the rest of the arguments. after creation, the caller has to set the provider's mediasize and sectorsize, plus any other initializations they want, and then call g_error_provider() to reset the provider's error — which is initially set to ENXIO. don't forget that part, bestie 🙈

g_destroy_provider() — destroys the given provider, cancels all related pending events, and removes the corresponding devfs entry. it's giving cleanup era ✨

g_error_provider() — used to set the provider's error value. if you set it to a nonzero, all I/O requests will be denied, and increasing its access count won't be possible either (the error error will be returned). so like, expect to be told no 💀

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💅 RESTRICTIONS/CONDITIONS 💅

g_new_provider():

• The provider name should be unique, but GEOM does not enforce this 🫠. if the name is not unique, you'll end up with two (or more) files with the same name — which is a programmer error. yeah. that's on you.
• The geom gp has to have a start method defined. required, no exceptions 🔥
• The topology lock has to be held. periodt.

g_destroy_provider():

• The provider must not have consumers attached. nope, not even one 🙅‍♀️
• The access count has to be 0.
• The topology lock has to be held. same rule as above, bestie.

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⭐ RETURN VALUES ⭐

The g_new_providerf() function returns a pointer to the newly created provider. slay 💖

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🌈 EXAMPLES 🌈

Create an example provider, set its parameters, and make it usable. look at her go 👑

struct g_provider *
create_example_provider(struct g_geom *gp)
{
        struct g_provider *pp;

        g_topology_lock();
        pp = g_new_providerf(gp, "example_provider");
        g_topology_unlock();
        pp->mediasize = 65536;
        pp->sectorsize = 512;
        g_error_provider(pp, 0);

        return (pp);
}

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🔥 SEE ALSO 🔥

geom(4), DECLARE_GEOM_CLASS(9), g_access(9), g_attach(9), g_bio(9), g_consumer(9), g_data(9), g_event(9), g_geom(9), g_provider_by_name(9), g_wither_geom(9) — go read these too, iykyk 📚

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👑 AUTHORS 👑

This manual page was written by Pawel Jakub Dawidek <pjd@FreeBSD.org>. ty king 🫶

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ngl this whole page is from the Debian edition of the Kernel Developer's Manual, dated January 16, 2004, and it's filed under G_PROVIDER(9). that's the vibe check, we're done here 💜✨