init, mount: export the name_to_dev_t symbol
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From: Christoph Hellwig on 25 May 2010 12:00 On Tue, May 25, 2010 at 10:46:51AM -0500, Will Drewry wrote: > This change only adds EXPORT_SYMBOL() for name_to_dev_t. > > name_to_dev_t is in use outside of init/ but is not 'officially' > exported. It provides behavior that is useful for any code that may be > need to lookup a block device by major:minor or registered kernel name, > especially before there is a root filesystem. > > Hopefully, this is the appropriate use of EXPORT_SYMBOL(). This > specific function seems to be a stable interface and is available > in include/linux/mount.h. NACK. It's really a hack for the boot code, there's no offical name to dev_t mapping. What are you trying to use it for? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Alasdair G Kergon on 25 May 2010 12:10 On Tue, May 25, 2010 at 11:55:35AM -0400, Christoph Hellwig wrote: > NACK. It's really a hack for the boot code, there's no offical name to > dev_t mapping. > What are you trying to use it for? Device-mapper contains a subset of that code, so he's proposing we use it here: @@ -434,17 +435,13 @@ static int __table_get_device(struct dm_ int r; dev_t uninitialized_var(dev); struct dm_dev_internal *dd; - unsigned int major, minor; BUG_ON(!t); - if (sscanf(path, "%u:%u", &major, &minor) == 2) { - /* Extract the major/minor numbers */ - dev = MKDEV(major, minor); - if (MAJOR(dev) != major || MINOR(dev) != minor) - return -EOVERFLOW; - } else { - /* convert the path to a device */ + /* lookup by major:minor or registered device name */ + dev = name_to_dev_t(path); + if (!dev) { + /* convert the path to a device by finding its inode */ struct block_device *bdev = lookup_bdev(path); if (IS_ERR(bdev)) Alasdair -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Will Drewry on 25 May 2010 12:20 On Tue, May 25, 2010 at 11:05 AM, Alasdair G Kergon <agk(a)redhat.com> wrote: > On Tue, May 25, 2010 at 11:55:35AM -0400, Christoph Hellwig wrote: >> NACK. �It's really a hack for the boot code, there's no offical name to >> dev_t mapping. >> What are you trying to use it for? > > Device-mapper contains a subset of that code, so he's proposing we > use it here: > > @@ -434,17 +435,13 @@ static int __table_get_device(struct dm_ > � � � �int r; > � � � �dev_t uninitialized_var(dev); > � � � �struct dm_dev_internal *dd; > - � � � unsigned int major, minor; > > � � � �BUG_ON(!t); > > - � � � if (sscanf(path, "%u:%u", &major, &minor) == 2) { > - � � � � � � � /* Extract the major/minor numbers */ > - � � � � � � � dev = MKDEV(major, minor); > - � � � � � � � if (MAJOR(dev) != major || MINOR(dev) != minor) > - � � � � � � � � � � � return -EOVERFLOW; > - � � � } else { > - � � � � � � � /* convert the path to a device */ > + � � � /* lookup by major:minor or registered device name */ > + � � � dev = name_to_dev_t(path); > + � � � if (!dev) { > + � � � � � � � /* convert the path to a device by finding its inode */ > � � � � � � � �struct block_device *bdev = lookup_bdev(path); > > � � � � � � � �if (IS_ERR(bdev)) In addition to getting rid of the code duplication, I'd like device-mapper to be able to resolve slave devices at boot-time to accommodate a do_mounts_dm.c equivalent to do_mounts_md.c: https://patchwork.kernel.org/patch/101024/ (which I neglected to mail to the other init-related maintainers - sorry! I'll correct that when I mail out the next revision.) thanks! will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Christoph Hellwig on 25 May 2010 13:30 On Tue, May 25, 2010 at 11:11:33AM -0500, Will Drewry wrote: > In addition to getting rid of the code duplication, I'd like device-mapper > to be able to resolve slave devices at boot-time to accommodate a > do_mounts_dm.c equivalent to do_mounts_md.c: So please add a do_mounts_dm.c instead of pushing this somewhere it doesn't belong to. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Mike Snitzer on 25 May 2010 14:40
On Tue, May 25 2010 at 1:21pm -0400, Christoph Hellwig <hch(a)infradead.org> wrote: > On Tue, May 25, 2010 at 11:11:33AM -0500, Will Drewry wrote: > > In addition to getting rid of the code duplication, I'd like device-mapper > > to be able to resolve slave devices at boot-time to accommodate a > > do_mounts_dm.c equivalent to do_mounts_md.c: > > So please add a do_mounts_dm.c instead of pushing this somewhere it > doesn't belong to. He is proposing doing just that, you cut out the patchwork url he already shared: https://patchwork.kernel.org/patch/101024/ Will's intentions are good: avoid code duplication. He is also trying to keep DM-specific common code in drivers/md/ So in this instance, avoiding the need to export name_to_dev_t would require splitting the internal DM __table_get_device (or more likely: dm_get_device) out to a public facing interface that takes a dev_t. Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |