From: Sascha Hauer <s.hauer@pengutronix.de>
To: Markus Pargmann <mpa@pengutronix.de>
Cc: barebox@lists.infradead.org, mgr@pengutronix.de
Subject: Re: [PATCH v2 5/6] state: backend_storage_direct: also use cached data on write
Date: Tue, 28 Jun 2016 08:18:47 +0200 [thread overview]
Message-ID: <20160628061847.GH20657@pengutronix.de> (raw)
In-Reply-To: <1466762762-15212-6-git-send-email-mpa@pengutronix.de>
On Fri, Jun 24, 2016 at 12:06:01PM +0200, Markus Pargmann wrote:
> From: Michael Grzeschik <m.grzeschik@pengutronix.de>
>
> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
> Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
> ---
> common/state/backend_bucket_direct.c | 55 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 55 insertions(+)
What's the problem this patch tries to solve?
Sascha
>
> diff --git a/common/state/backend_bucket_direct.c b/common/state/backend_bucket_direct.c
> index 08892f001e25..772267f6dc1d 100644
> --- a/common/state/backend_bucket_direct.c
> +++ b/common/state/backend_bucket_direct.c
> @@ -29,6 +29,10 @@ struct state_backend_storage_bucket_direct {
>
> int fd;
>
> + /* Cached data of the last read/write */
> + u8 *current_data;
> + ssize_t current_data_len;
> +
> struct device_d *dev;
> };
>
> @@ -99,6 +103,29 @@ static int state_backend_bucket_direct_read(struct state_backend_storage_bucket
> return 0;
> }
>
> +
> +static int state_backend_bucket_direct_fill_cache(
> + struct state_backend_storage_bucket *bucket)
> +{
> + struct state_backend_storage_bucket_direct *direct =
> + get_bucket_direct(bucket);
> + ssize_t read_len;
> + uint8_t *buf;
> + int ret;
> +
> + ret = state_backend_bucket_direct_read(bucket, &buf, &read_len);
> + if (ret < 0) {
> + dev_err(direct->dev, "Failed to read from file, %d\n", ret);
> + free(buf);
> + return ret;
> + }
> +
> + direct->current_data = buf;
> + direct->current_data_len = read_len;
> +
> + return 0;
> +}
> +
> static int state_backend_bucket_direct_write(struct state_backend_storage_bucket
> *bucket, const uint8_t * buf,
> ssize_t len)
> @@ -111,6 +138,11 @@ static int state_backend_bucket_direct_write(struct state_backend_storage_bucket
> if (direct->max_size && len > direct->max_size)
> return -E2BIG;
>
> + /* Nothing in cache? Then read to see what is on the device currently */
> + if (!direct->current_data) {
> + state_backend_bucket_direct_fill_cache(bucket);
> + }
> +
> ret = lseek(direct->fd, direct->offset, SEEK_SET);
> if (ret < 0) {
> dev_err(direct->dev, "Failed to seek file, %d\n", ret);
> @@ -119,6 +151,26 @@ static int state_backend_bucket_direct_write(struct state_backend_storage_bucket
>
> meta.magic = direct_magic;
> meta.written_length = len;
> +
> + /*
> + * If we would write the same data that is currently on the device, we
> + * can return successfully without writing.
> + * Note that the cache may still be empty if the storage is empty or
> + * errors occured.
> + */
> + if (direct->current_data) {
> + dev_dbg(direct->dev, "Comparing cached data, writing %zd bytes, cached %zd bytes\n",
> + len, direct->current_data_len);
> + if (len == direct->current_data_len &&
> + !memcmp(direct->current_data, buf, len)) {
> + dev_dbg(direct->dev, "Data already on device, not writing again\n");
> + return ret;
> + } else {
> + free(direct->current_data);
> + direct->current_data = NULL;
> + }
> + }
> +
> ret = write_full(direct->fd, &meta, sizeof(meta));
> if (ret < 0) {
> dev_err(direct->dev, "Failed to write metadata to file, %d\n", ret);
> @@ -147,6 +199,9 @@ static void state_backend_bucket_direct_free(struct
> struct state_backend_storage_bucket_direct *direct =
> get_bucket_direct(bucket);
>
> + if (direct->current_data)
> + free(direct->current_data);
> +
> close(direct->fd);
> free(direct);
> }
> --
> 2.8.1
>
>
> _______________________________________________
> barebox mailing list
> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox
>
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
next prev parent reply other threads:[~2016-06-28 6:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-24 10:05 [PATCH v2 0/6] state: Refactor backend Markus Pargmann
2016-06-24 10:05 ` [PATCH v2 1/6] libfile: Change write_full to be have const buf Markus Pargmann
2016-06-24 10:05 ` [PATCH v2 2/6] state: Refactor state framework Markus Pargmann
2016-06-24 10:05 ` [PATCH v2 3/6] docs: Add/Update state documentation Markus Pargmann
2016-06-24 10:06 ` [PATCH v2 4/6] state: also append backend storage stridesize Markus Pargmann
2016-06-24 10:06 ` [PATCH v2 5/6] state: backend_storage_direct: also use cached data on write Markus Pargmann
2016-06-28 6:18 ` Sascha Hauer [this message]
2016-06-28 6:55 ` Michael Grzeschik
2016-06-29 5:56 ` Markus Pargmann
2016-06-24 10:06 ` [PATCH v2 6/6] barebox-state: handle flush errno correctly Markus Pargmann
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=20160628061847.GH20657@pengutronix.de \
--to=s.hauer@pengutronix.de \
--cc=barebox@lists.infradead.org \
--cc=mgr@pengutronix.de \
--cc=mpa@pengutronix.de \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox