RE: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices
> -Original Message- > From: Linux-nvdimm [mailto:linux-nvdimm-boun...@lists.01.org] On Behalf > Of Dan Williams > Sent: Thursday, May 14, 2015 7:42 PM > To: Kani, Toshimitsu > Cc: Neil Brown; Greg KH; linux-kernel@vger.kernel.org; linux- > nvd...@lists.01.org > Subject: Re: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for > btt devices > ... > So we can fix this to be at least as stable as the backing device > names [1], but as far as I can see we would need to start using the > backing device name in the btt device name. A strawman proposal is to > append 's' to indicated 'sectored'. So /dev/pmem0s is the btt > instance fronting /dev/pmem0. Other examples: > > /dev/pmem0p1s > /dev/ndblk0.0s > /dev/ndblk0.0p1s > ... > > Thoughts? > > [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-April/000636.html I like that; it also hints to the user that another driver has already claimed /dev/pmem0, similar to how the presence of /dev/sda1, /dev/sda2, etc. hints that a program has partitioned /dev/sda. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices
On Tue, May 12, 2015 at 9:33 AM, Toshi Kani wrote:
> On Tue, 2015-04-28 at 14:25 -0400, Dan Williams wrote:
>> Block devices from an nd bus, in addition to accepting "struct bio"
>> based requests, also have the capability to perform byte-aligned
>> accesses. By default only the bio/block interface is used. However, if
>> another driver can make effective use of the byte-aligned capability it
>> can claim/disable the block interface and use the byte-aligned "nd_io"
>> interface.
>>
>> The BTT driver is the intended first consumer of this mechanism to allow
>> layering atomic sector update guarantees on top of nd_io capable
>> nd-bus-block-devices.
> :
>> +static int nd_btt_autodetect(struct nd_bus *nd_bus, struct nd_io *ndio,
>> + struct block_device *bdev)
>> +{
>> + char name[BDEVNAME_SIZE];
>> + struct nd_btt *nd_btt;
>> + struct btt_sb *btt_sb;
>> + u64 offset, checksum;
>> + u32 lbasize;
>> + u8 *uuid;
>> + int rc;
>> +
>> + btt_sb = kzalloc(sizeof(*btt_sb), GFP_KERNEL);
>> + if (!btt_sb)
>> + return -ENODEV;
>> +
>> + offset = nd_partition_offset(bdev);
>> + rc = ndio->rw_bytes(ndio, btt_sb, offset + SZ_4K, sizeof(*btt_sb),
>> READ);
>> + if (rc)
>> + goto out_free_sb;
>> +
>> + if (get_capacity(bdev->bd_disk) < SZ_16M / 512)
>> + goto out_free_sb;
>> +
>> + if (memcmp(btt_sb->signature, BTT_SIG, BTT_SIG_LEN) != 0)
>> + goto out_free_sb;
>> +
>> + checksum = le64_to_cpu(btt_sb->checksum);
>> + btt_sb->checksum = 0;
>> + if (checksum != nd_btt_sb_checksum(btt_sb))
>> + goto out_free_sb;
>> + btt_sb->checksum = cpu_to_le64(checksum);
>> +
>> + uuid = kmemdup(btt_sb->uuid, 16, GFP_KERNEL);
>> + if (!uuid)
>> + goto out_free_sb;
>> +
>> + lbasize = le32_to_cpu(btt_sb->external_lbasize);
>> + nd_btt = __nd_btt_create(nd_bus, lbasize, uuid);
>
> When BTT is first set up, user binds a seed "btt0" to a block device,
> such as /dev/pmem0. It then creates /dev/nd0 bound to /dev/pmem0.
>
> After a reboot, nd_btt_autodetect() detects the BTT setup and creates a
> new "btt1" since it is called after a seed "btt0" is created.
> Therefore, it creates /dev/nd1 bound to /dev/pmem0 this time.
>
> Is this how it is intended to work, i.e. "btt0" as the default seed btt?
> While user should not rely on the name of /dev/nd%d, I thought this
> device name change was confusing...
So we can fix this to be at least as stable as the backing device
names [1], but as far as I can see we would need to start using the
backing device name in the btt device name. A strawman proposal is to
append 's' to indicated 'sectored'. So /dev/pmem0s is the btt
instance fronting /dev/pmem0. Other examples:
/dev/pmem0p1s
/dev/ndblk0.0s
/dev/ndblk0.0p1s
...
Thoughts?
[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-April/000636.html
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More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices
On Tue, May 12, 2015 at 9:33 AM, Toshi Kani toshi.k...@hp.com wrote:
On Tue, 2015-04-28 at 14:25 -0400, Dan Williams wrote:
Block devices from an nd bus, in addition to accepting struct bio
based requests, also have the capability to perform byte-aligned
accesses. By default only the bio/block interface is used. However, if
another driver can make effective use of the byte-aligned capability it
can claim/disable the block interface and use the byte-aligned nd_io
interface.
The BTT driver is the intended first consumer of this mechanism to allow
layering atomic sector update guarantees on top of nd_io capable
nd-bus-block-devices.
:
+static int nd_btt_autodetect(struct nd_bus *nd_bus, struct nd_io *ndio,
+ struct block_device *bdev)
+{
+ char name[BDEVNAME_SIZE];
+ struct nd_btt *nd_btt;
+ struct btt_sb *btt_sb;
+ u64 offset, checksum;
+ u32 lbasize;
+ u8 *uuid;
+ int rc;
+
+ btt_sb = kzalloc(sizeof(*btt_sb), GFP_KERNEL);
+ if (!btt_sb)
+ return -ENODEV;
+
+ offset = nd_partition_offset(bdev);
+ rc = ndio-rw_bytes(ndio, btt_sb, offset + SZ_4K, sizeof(*btt_sb),
READ);
+ if (rc)
+ goto out_free_sb;
+
+ if (get_capacity(bdev-bd_disk) SZ_16M / 512)
+ goto out_free_sb;
+
+ if (memcmp(btt_sb-signature, BTT_SIG, BTT_SIG_LEN) != 0)
+ goto out_free_sb;
+
+ checksum = le64_to_cpu(btt_sb-checksum);
+ btt_sb-checksum = 0;
+ if (checksum != nd_btt_sb_checksum(btt_sb))
+ goto out_free_sb;
+ btt_sb-checksum = cpu_to_le64(checksum);
+
+ uuid = kmemdup(btt_sb-uuid, 16, GFP_KERNEL);
+ if (!uuid)
+ goto out_free_sb;
+
+ lbasize = le32_to_cpu(btt_sb-external_lbasize);
+ nd_btt = __nd_btt_create(nd_bus, lbasize, uuid);
When BTT is first set up, user binds a seed btt0 to a block device,
such as /dev/pmem0. It then creates /dev/nd0 bound to /dev/pmem0.
After a reboot, nd_btt_autodetect() detects the BTT setup and creates a
new btt1 since it is called after a seed btt0 is created.
Therefore, it creates /dev/nd1 bound to /dev/pmem0 this time.
Is this how it is intended to work, i.e. btt0 as the default seed btt?
While user should not rely on the name of /dev/nd%d, I thought this
device name change was confusing...
So we can fix this to be at least as stable as the backing device
names [1], but as far as I can see we would need to start using the
backing device name in the btt device name. A strawman proposal is to
append 's' to indicated 'sectored'. So /dev/pmem0s is the btt
instance fronting /dev/pmem0. Other examples:
/dev/pmem0p1s
/dev/ndblk0.0s
/dev/ndblk0.0p1s
...
Thoughts?
[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-April/000636.html
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To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
RE: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices
-Original Message- From: Linux-nvdimm [mailto:linux-nvdimm-boun...@lists.01.org] On Behalf Of Dan Williams Sent: Thursday, May 14, 2015 7:42 PM To: Kani, Toshimitsu Cc: Neil Brown; Greg KH; linux-kernel@vger.kernel.org; linux- nvd...@lists.01.org Subject: Re: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices ... So we can fix this to be at least as stable as the backing device names [1], but as far as I can see we would need to start using the backing device name in the btt device name. A strawman proposal is to append 's' to indicated 'sectored'. So /dev/pmem0s is the btt instance fronting /dev/pmem0. Other examples: /dev/pmem0p1s /dev/ndblk0.0s /dev/ndblk0.0p1s ... Thoughts? [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-April/000636.html I like that; it also hints to the user that another driver has already claimed /dev/pmem0, similar to how the presence of /dev/sda1, /dev/sda2, etc. hints that a program has partitioned /dev/sda. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices
On Tue, 2015-04-28 at 14:25 -0400, Dan Williams wrote:
> Block devices from an nd bus, in addition to accepting "struct bio"
> based requests, also have the capability to perform byte-aligned
> accesses. By default only the bio/block interface is used. However, if
> another driver can make effective use of the byte-aligned capability it
> can claim/disable the block interface and use the byte-aligned "nd_io"
> interface.
>
> The BTT driver is the intended first consumer of this mechanism to allow
> layering atomic sector update guarantees on top of nd_io capable
> nd-bus-block-devices.
:
> +static int nd_btt_autodetect(struct nd_bus *nd_bus, struct nd_io *ndio,
> + struct block_device *bdev)
> +{
> + char name[BDEVNAME_SIZE];
> + struct nd_btt *nd_btt;
> + struct btt_sb *btt_sb;
> + u64 offset, checksum;
> + u32 lbasize;
> + u8 *uuid;
> + int rc;
> +
> + btt_sb = kzalloc(sizeof(*btt_sb), GFP_KERNEL);
> + if (!btt_sb)
> + return -ENODEV;
> +
> + offset = nd_partition_offset(bdev);
> + rc = ndio->rw_bytes(ndio, btt_sb, offset + SZ_4K, sizeof(*btt_sb),
> READ);
> + if (rc)
> + goto out_free_sb;
> +
> + if (get_capacity(bdev->bd_disk) < SZ_16M / 512)
> + goto out_free_sb;
> +
> + if (memcmp(btt_sb->signature, BTT_SIG, BTT_SIG_LEN) != 0)
> + goto out_free_sb;
> +
> + checksum = le64_to_cpu(btt_sb->checksum);
> + btt_sb->checksum = 0;
> + if (checksum != nd_btt_sb_checksum(btt_sb))
> + goto out_free_sb;
> + btt_sb->checksum = cpu_to_le64(checksum);
> +
> + uuid = kmemdup(btt_sb->uuid, 16, GFP_KERNEL);
> + if (!uuid)
> + goto out_free_sb;
> +
> + lbasize = le32_to_cpu(btt_sb->external_lbasize);
> + nd_btt = __nd_btt_create(nd_bus, lbasize, uuid);
When BTT is first set up, user binds a seed "btt0" to a block device,
such as /dev/pmem0. It then creates /dev/nd0 bound to /dev/pmem0.
After a reboot, nd_btt_autodetect() detects the BTT setup and creates a
new "btt1" since it is called after a seed "btt0" is created.
Therefore, it creates /dev/nd1 bound to /dev/pmem0 this time.
Is this how it is intended to work, i.e. "btt0" as the default seed btt?
While user should not rely on the name of /dev/nd%d, I thought this
device name change was confusing...
Thanks,
-Toshi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [Linux-nvdimm] [PATCH v2 18/20] libnd: infrastructure for btt devices
On Tue, 2015-04-28 at 14:25 -0400, Dan Williams wrote:
Block devices from an nd bus, in addition to accepting struct bio
based requests, also have the capability to perform byte-aligned
accesses. By default only the bio/block interface is used. However, if
another driver can make effective use of the byte-aligned capability it
can claim/disable the block interface and use the byte-aligned nd_io
interface.
The BTT driver is the intended first consumer of this mechanism to allow
layering atomic sector update guarantees on top of nd_io capable
nd-bus-block-devices.
:
+static int nd_btt_autodetect(struct nd_bus *nd_bus, struct nd_io *ndio,
+ struct block_device *bdev)
+{
+ char name[BDEVNAME_SIZE];
+ struct nd_btt *nd_btt;
+ struct btt_sb *btt_sb;
+ u64 offset, checksum;
+ u32 lbasize;
+ u8 *uuid;
+ int rc;
+
+ btt_sb = kzalloc(sizeof(*btt_sb), GFP_KERNEL);
+ if (!btt_sb)
+ return -ENODEV;
+
+ offset = nd_partition_offset(bdev);
+ rc = ndio-rw_bytes(ndio, btt_sb, offset + SZ_4K, sizeof(*btt_sb),
READ);
+ if (rc)
+ goto out_free_sb;
+
+ if (get_capacity(bdev-bd_disk) SZ_16M / 512)
+ goto out_free_sb;
+
+ if (memcmp(btt_sb-signature, BTT_SIG, BTT_SIG_LEN) != 0)
+ goto out_free_sb;
+
+ checksum = le64_to_cpu(btt_sb-checksum);
+ btt_sb-checksum = 0;
+ if (checksum != nd_btt_sb_checksum(btt_sb))
+ goto out_free_sb;
+ btt_sb-checksum = cpu_to_le64(checksum);
+
+ uuid = kmemdup(btt_sb-uuid, 16, GFP_KERNEL);
+ if (!uuid)
+ goto out_free_sb;
+
+ lbasize = le32_to_cpu(btt_sb-external_lbasize);
+ nd_btt = __nd_btt_create(nd_bus, lbasize, uuid);
When BTT is first set up, user binds a seed btt0 to a block device,
such as /dev/pmem0. It then creates /dev/nd0 bound to /dev/pmem0.
After a reboot, nd_btt_autodetect() detects the BTT setup and creates a
new btt1 since it is called after a seed btt0 is created.
Therefore, it creates /dev/nd1 bound to /dev/pmem0 this time.
Is this how it is intended to work, i.e. btt0 as the default seed btt?
While user should not rely on the name of /dev/nd%d, I thought this
device name change was confusing...
Thanks,
-Toshi
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
