From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bHmMX-0004Ah-So for barebox@lists.infradead.org; Tue, 28 Jun 2016 06:19:10 +0000 Date: Tue, 28 Jun 2016 08:18:47 +0200 From: Sascha Hauer Message-ID: <20160628061847.GH20657@pengutronix.de> References: <1466762762-15212-1-git-send-email-mpa@pengutronix.de> <1466762762-15212-6-git-send-email-mpa@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1466762762-15212-6-git-send-email-mpa@pengutronix.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH v2 5/6] state: backend_storage_direct: also use cached data on write To: Markus Pargmann Cc: barebox@lists.infradead.org, mgr@pengutronix.de On Fri, Jun 24, 2016 at 12:06:01PM +0200, Markus Pargmann wrote: > From: Michael Grzeschik > > Signed-off-by: Michael Grzeschik > Signed-off-by: Markus Pargmann > --- > 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