From: Dan Williams <dan.j.williams@intel.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Christoph Hellwig <hch@infradead.org>,
david <david@fromorbit.com>,
device-mapper development <dm-devel@redhat.com>,
Mike Snitzer <msnitzer@redhat.com>
Subject: Re: [PATCH v6 4/6] dm,dax: Add dax zero_page_range operation
Date: Tue, 31 Mar 2020 12:34:36 -0700 [thread overview]
Message-ID: <CAPcyv4iWfL+KQjjUXqrTKOL8F4M05Vu=imm5tqsD6MO=XLzoMA@mail.gmail.com> (raw)
In-Reply-To: <20200228163456.1587-5-vgoyal@redhat.com>
[ Add Mike ]
On Fri, Feb 28, 2020 at 8:35 AM Vivek Goyal <vgoyal@redhat.com> wrote:
>
> This patch adds support for dax zero_page_range operation to dm targets.
Mike,
Sorry, I should have pinged you earlier, but could you take a look at
this patch and ack it if it looks ok to go through the nvdimm tree
with the rest of the series?
>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
> drivers/md/dm-linear.c | 18 ++++++++++++++++++
> drivers/md/dm-log-writes.c | 17 +++++++++++++++++
> drivers/md/dm-stripe.c | 23 +++++++++++++++++++++++
> drivers/md/dm.c | 30 ++++++++++++++++++++++++++++++
> include/linux/device-mapper.h | 3 +++
> 5 files changed, 91 insertions(+)
>
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 8d07fdf63a47..e1db43446327 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -201,10 +201,27 @@ static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
> return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
> }
>
> +static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + int ret;
> + struct linear_c *lc = ti->private;
> + struct block_device *bdev = lc->dev->bdev;
> + struct dax_device *dax_dev = lc->dev->dax_dev;
> + sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
> +
> + dev_sector = linear_map_sector(ti, sector);
> + ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
> + if (ret)
> + return ret;
> + return dax_zero_page_range(dax_dev, pgoff, nr_pages);
> +}
> +
> #else
> #define linear_dax_direct_access NULL
> #define linear_dax_copy_from_iter NULL
> #define linear_dax_copy_to_iter NULL
> +#define linear_dax_zero_page_range NULL
> #endif
>
> static struct target_type linear_target = {
> @@ -226,6 +243,7 @@ static struct target_type linear_target = {
> .direct_access = linear_dax_direct_access,
> .dax_copy_from_iter = linear_dax_copy_from_iter,
> .dax_copy_to_iter = linear_dax_copy_to_iter,
> + .dax_zero_page_range = linear_dax_zero_page_range,
> };
>
> int __init dm_linear_init(void)
> diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
> index 99721c76225d..8ea20b56b4d6 100644
> --- a/drivers/md/dm-log-writes.c
> +++ b/drivers/md/dm-log-writes.c
> @@ -994,10 +994,26 @@ static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
> return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
> }
>
> +static int log_writes_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + int ret;
> + struct log_writes_c *lc = ti->private;
> + sector_t sector = pgoff * PAGE_SECTORS;
> +
> + ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages << PAGE_SHIFT,
> + &pgoff);
> + if (ret)
> + return ret;
> + return dax_zero_page_range(lc->dev->dax_dev, pgoff,
> + nr_pages << PAGE_SHIFT);
> +}
> +
> #else
> #define log_writes_dax_direct_access NULL
> #define log_writes_dax_copy_from_iter NULL
> #define log_writes_dax_copy_to_iter NULL
> +#define log_writes_dax_zero_page_range NULL
> #endif
>
> static struct target_type log_writes_target = {
> @@ -1016,6 +1032,7 @@ static struct target_type log_writes_target = {
> .direct_access = log_writes_dax_direct_access,
> .dax_copy_from_iter = log_writes_dax_copy_from_iter,
> .dax_copy_to_iter = log_writes_dax_copy_to_iter,
> + .dax_zero_page_range = log_writes_dax_zero_page_range,
> };
>
> static int __init dm_log_writes_init(void)
> diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
> index 63bbcc20f49a..fa813c0f993d 100644
> --- a/drivers/md/dm-stripe.c
> +++ b/drivers/md/dm-stripe.c
> @@ -360,10 +360,32 @@ static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
> return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
> }
>
> +static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + int ret;
> + sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
> + struct stripe_c *sc = ti->private;
> + struct dax_device *dax_dev;
> + struct block_device *bdev;
> + uint32_t stripe;
> +
> + stripe_map_sector(sc, sector, &stripe, &dev_sector);
> + dev_sector += sc->stripe[stripe].physical_start;
> + dax_dev = sc->stripe[stripe].dev->dax_dev;
> + bdev = sc->stripe[stripe].dev->bdev;
> +
> + ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
> + if (ret)
> + return ret;
> + return dax_zero_page_range(dax_dev, pgoff, nr_pages);
> +}
> +
> #else
> #define stripe_dax_direct_access NULL
> #define stripe_dax_copy_from_iter NULL
> #define stripe_dax_copy_to_iter NULL
> +#define stripe_dax_zero_page_range NULL
> #endif
>
> /*
> @@ -486,6 +508,7 @@ static struct target_type stripe_target = {
> .direct_access = stripe_dax_direct_access,
> .dax_copy_from_iter = stripe_dax_copy_from_iter,
> .dax_copy_to_iter = stripe_dax_copy_to_iter,
> + .dax_zero_page_range = stripe_dax_zero_page_range,
> };
>
> int __init dm_stripe_init(void)
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index b89f07ee2eff..aa72d9e757c1 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1198,6 +1198,35 @@ static size_t dm_dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
> return ret;
> }
>
> +static int dm_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + struct mapped_device *md = dax_get_private(dax_dev);
> + sector_t sector = pgoff * PAGE_SECTORS;
> + struct dm_target *ti;
> + int ret = -EIO;
> + int srcu_idx;
> +
> + ti = dm_dax_get_live_target(md, sector, &srcu_idx);
> +
> + if (!ti)
> + goto out;
> + if (WARN_ON(!ti->type->dax_zero_page_range)) {
> + /*
> + * ->zero_page_range() is mandatory dax operation. If we are
> + * here, something is wrong.
> + */
> + dm_put_live_table(md, srcu_idx);
> + goto out;
> + }
> + ret = ti->type->dax_zero_page_range(ti, pgoff, nr_pages);
> +
> + out:
> + dm_put_live_table(md, srcu_idx);
> +
> + return ret;
> +}
> +
> /*
> * A target may call dm_accept_partial_bio only from the map routine. It is
> * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_RESET,
> @@ -3199,6 +3228,7 @@ static const struct dax_operations dm_dax_ops = {
> .dax_supported = dm_dax_supported,
> .copy_from_iter = dm_dax_copy_from_iter,
> .copy_to_iter = dm_dax_copy_to_iter,
> + .zero_page_range = dm_dax_zero_page_range,
> };
>
> /*
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 475668c69dbc..af48d9da3916 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -141,6 +141,8 @@ typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
> long nr_pages, void **kaddr, pfn_t *pfn);
> typedef size_t (*dm_dax_copy_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
> void *addr, size_t bytes, struct iov_iter *i);
> +typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages);
> #define PAGE_SECTORS (PAGE_SIZE / 512)
>
> void dm_error(const char *message);
> @@ -195,6 +197,7 @@ struct target_type {
> dm_dax_direct_access_fn direct_access;
> dm_dax_copy_iter_fn dax_copy_from_iter;
> dm_dax_copy_iter_fn dax_copy_to_iter;
> + dm_dax_zero_page_range_fn dax_zero_page_range;
>
> /* For internal device-mapper use. */
> struct list_head list;
> --
> 2.20.1
>
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Christoph Hellwig <hch@infradead.org>,
david <david@fromorbit.com>, jmoyer <jmoyer@redhat.com>,
device-mapper development <dm-devel@redhat.com>,
Mike Snitzer <msnitzer@redhat.com>
Subject: Re: [PATCH v6 4/6] dm,dax: Add dax zero_page_range operation
Date: Tue, 31 Mar 2020 12:34:36 -0700 [thread overview]
Message-ID: <CAPcyv4iWfL+KQjjUXqrTKOL8F4M05Vu=imm5tqsD6MO=XLzoMA@mail.gmail.com> (raw)
In-Reply-To: <20200228163456.1587-5-vgoyal@redhat.com>
[ Add Mike ]
On Fri, Feb 28, 2020 at 8:35 AM Vivek Goyal <vgoyal@redhat.com> wrote:
>
> This patch adds support for dax zero_page_range operation to dm targets.
Mike,
Sorry, I should have pinged you earlier, but could you take a look at
this patch and ack it if it looks ok to go through the nvdimm tree
with the rest of the series?
>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> ---
> drivers/md/dm-linear.c | 18 ++++++++++++++++++
> drivers/md/dm-log-writes.c | 17 +++++++++++++++++
> drivers/md/dm-stripe.c | 23 +++++++++++++++++++++++
> drivers/md/dm.c | 30 ++++++++++++++++++++++++++++++
> include/linux/device-mapper.h | 3 +++
> 5 files changed, 91 insertions(+)
>
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 8d07fdf63a47..e1db43446327 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -201,10 +201,27 @@ static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
> return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
> }
>
> +static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + int ret;
> + struct linear_c *lc = ti->private;
> + struct block_device *bdev = lc->dev->bdev;
> + struct dax_device *dax_dev = lc->dev->dax_dev;
> + sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
> +
> + dev_sector = linear_map_sector(ti, sector);
> + ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
> + if (ret)
> + return ret;
> + return dax_zero_page_range(dax_dev, pgoff, nr_pages);
> +}
> +
> #else
> #define linear_dax_direct_access NULL
> #define linear_dax_copy_from_iter NULL
> #define linear_dax_copy_to_iter NULL
> +#define linear_dax_zero_page_range NULL
> #endif
>
> static struct target_type linear_target = {
> @@ -226,6 +243,7 @@ static struct target_type linear_target = {
> .direct_access = linear_dax_direct_access,
> .dax_copy_from_iter = linear_dax_copy_from_iter,
> .dax_copy_to_iter = linear_dax_copy_to_iter,
> + .dax_zero_page_range = linear_dax_zero_page_range,
> };
>
> int __init dm_linear_init(void)
> diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
> index 99721c76225d..8ea20b56b4d6 100644
> --- a/drivers/md/dm-log-writes.c
> +++ b/drivers/md/dm-log-writes.c
> @@ -994,10 +994,26 @@ static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
> return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
> }
>
> +static int log_writes_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + int ret;
> + struct log_writes_c *lc = ti->private;
> + sector_t sector = pgoff * PAGE_SECTORS;
> +
> + ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages << PAGE_SHIFT,
> + &pgoff);
> + if (ret)
> + return ret;
> + return dax_zero_page_range(lc->dev->dax_dev, pgoff,
> + nr_pages << PAGE_SHIFT);
> +}
> +
> #else
> #define log_writes_dax_direct_access NULL
> #define log_writes_dax_copy_from_iter NULL
> #define log_writes_dax_copy_to_iter NULL
> +#define log_writes_dax_zero_page_range NULL
> #endif
>
> static struct target_type log_writes_target = {
> @@ -1016,6 +1032,7 @@ static struct target_type log_writes_target = {
> .direct_access = log_writes_dax_direct_access,
> .dax_copy_from_iter = log_writes_dax_copy_from_iter,
> .dax_copy_to_iter = log_writes_dax_copy_to_iter,
> + .dax_zero_page_range = log_writes_dax_zero_page_range,
> };
>
> static int __init dm_log_writes_init(void)
> diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
> index 63bbcc20f49a..fa813c0f993d 100644
> --- a/drivers/md/dm-stripe.c
> +++ b/drivers/md/dm-stripe.c
> @@ -360,10 +360,32 @@ static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
> return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
> }
>
> +static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + int ret;
> + sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
> + struct stripe_c *sc = ti->private;
> + struct dax_device *dax_dev;
> + struct block_device *bdev;
> + uint32_t stripe;
> +
> + stripe_map_sector(sc, sector, &stripe, &dev_sector);
> + dev_sector += sc->stripe[stripe].physical_start;
> + dax_dev = sc->stripe[stripe].dev->dax_dev;
> + bdev = sc->stripe[stripe].dev->bdev;
> +
> + ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
> + if (ret)
> + return ret;
> + return dax_zero_page_range(dax_dev, pgoff, nr_pages);
> +}
> +
> #else
> #define stripe_dax_direct_access NULL
> #define stripe_dax_copy_from_iter NULL
> #define stripe_dax_copy_to_iter NULL
> +#define stripe_dax_zero_page_range NULL
> #endif
>
> /*
> @@ -486,6 +508,7 @@ static struct target_type stripe_target = {
> .direct_access = stripe_dax_direct_access,
> .dax_copy_from_iter = stripe_dax_copy_from_iter,
> .dax_copy_to_iter = stripe_dax_copy_to_iter,
> + .dax_zero_page_range = stripe_dax_zero_page_range,
> };
>
> int __init dm_stripe_init(void)
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index b89f07ee2eff..aa72d9e757c1 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1198,6 +1198,35 @@ static size_t dm_dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
> return ret;
> }
>
> +static int dm_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
> + size_t nr_pages)
> +{
> + struct mapped_device *md = dax_get_private(dax_dev);
> + sector_t sector = pgoff * PAGE_SECTORS;
> + struct dm_target *ti;
> + int ret = -EIO;
> + int srcu_idx;
> +
> + ti = dm_dax_get_live_target(md, sector, &srcu_idx);
> +
> + if (!ti)
> + goto out;
> + if (WARN_ON(!ti->type->dax_zero_page_range)) {
> + /*
> + * ->zero_page_range() is mandatory dax operation. If we are
> + * here, something is wrong.
> + */
> + dm_put_live_table(md, srcu_idx);
> + goto out;
> + }
> + ret = ti->type->dax_zero_page_range(ti, pgoff, nr_pages);
> +
> + out:
> + dm_put_live_table(md, srcu_idx);
> +
> + return ret;
> +}
> +
> /*
> * A target may call dm_accept_partial_bio only from the map routine. It is
> * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_RESET,
> @@ -3199,6 +3228,7 @@ static const struct dax_operations dm_dax_ops = {
> .dax_supported = dm_dax_supported,
> .copy_from_iter = dm_dax_copy_from_iter,
> .copy_to_iter = dm_dax_copy_to_iter,
> + .zero_page_range = dm_dax_zero_page_range,
> };
>
> /*
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 475668c69dbc..af48d9da3916 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -141,6 +141,8 @@ typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
> long nr_pages, void **kaddr, pfn_t *pfn);
> typedef size_t (*dm_dax_copy_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
> void *addr, size_t bytes, struct iov_iter *i);
> +typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
> + size_t nr_pages);
> #define PAGE_SECTORS (PAGE_SIZE / 512)
>
> void dm_error(const char *message);
> @@ -195,6 +197,7 @@ struct target_type {
> dm_dax_direct_access_fn direct_access;
> dm_dax_copy_iter_fn dax_copy_from_iter;
> dm_dax_copy_iter_fn dax_copy_to_iter;
> + dm_dax_zero_page_range_fn dax_zero_page_range;
>
> /* For internal device-mapper use. */
> struct list_head list;
> --
> 2.20.1
>
next prev parent reply other threads:[~2020-03-31 19:34 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 16:34 [PATCH v6 0/6] dax/pmem: Provide a dax operation to zero page range Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-02-28 16:34 ` [PATCH v6 1/6] pmem: Add functions for reading/writing page to/from pmem Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-02-29 8:04 ` Pankaj Gupta
2020-02-29 8:04 ` Pankaj Gupta
2020-03-04 16:16 ` Christoph Hellwig
2020-03-04 16:16 ` Christoph Hellwig
2020-03-04 18:44 ` Vivek Goyal
2020-03-04 18:44 ` Vivek Goyal
2020-02-28 16:34 ` [PATCH v6 2/6] dax, pmem: Add a dax operation zero_page_range Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-02-29 9:21 ` Pankaj Gupta
2020-02-29 9:21 ` Pankaj Gupta
2020-02-28 16:34 ` [PATCH v6 3/6] s390,dcssblk,dax: Add dax zero_page_range operation to dcssblk driver Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-02-28 16:34 ` [PATCH v6 4/6] dm,dax: Add dax zero_page_range operation Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-03-31 19:34 ` Dan Williams [this message]
2020-03-31 19:34 ` Dan Williams
2020-04-03 0:49 ` Dan Williams
2020-04-03 0:49 ` Dan Williams
2020-04-03 1:02 ` Mike Snitzer
2020-04-03 1:02 ` Mike Snitzer
2020-02-28 16:34 ` [PATCH v6 5/6] dax: Use new dax zero page method for zeroing a page Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-02-28 16:34 ` [PATCH v6 6/6] dax,iomap: Add helper dax_iomap_zero() to zero a range Vivek Goyal
2020-02-28 16:34 ` Vivek Goyal
2020-02-29 9:16 ` [PATCH v6 0/6] dax/pmem: Provide a dax operation to zero page range Pankaj Gupta
2020-02-29 9:16 ` Pankaj Gupta
2020-03-10 12:18 ` Vivek Goyal
2020-03-10 12:18 ` Vivek Goyal
2020-04-01 16:11 ` [PATCH v6 7/6] dax: Move mandatory ->zero_page_range() check in alloc_dax() Vivek Goyal
2020-04-01 16:11 ` Vivek Goyal
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAPcyv4iWfL+KQjjUXqrTKOL8F4M05Vu=imm5tqsD6MO=XLzoMA@mail.gmail.com' \
--to=dan.j.williams@intel.com \
--cc=david@fromorbit.com \
--cc=dm-devel@redhat.com \
--cc=hch@infradead.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-nvdimm@lists.01.org \
--cc=msnitzer@redhat.com \
--cc=vgoyal@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.