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From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
To: Damien Le Moal <Damien.LeMoal@wdc.com>
Cc: linux-fsdevel@vger.kernel.org,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>
Subject: [PATCH v2 3/3] zonefs: document the explicit-open mount option
Date: Wed,  9 Sep 2020 19:26:14 +0900	[thread overview]
Message-ID: <20200909102614.40585-4-johannes.thumshirn@wdc.com> (raw)
In-Reply-To: <20200909102614.40585-1-johannes.thumshirn@wdc.com>

Document the newly introduced explicit-open mount option.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

---
Changes to v1:
- Address Randy's comments
---
 Documentation/filesystems/zonefs.rst | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/filesystems/zonefs.rst b/Documentation/filesystems/zonefs.rst
index 6c18bc8ce332..6b213fe9a33e 100644
--- a/Documentation/filesystems/zonefs.rst
+++ b/Documentation/filesystems/zonefs.rst
@@ -326,6 +326,21 @@ discover the amount of data that has been written to the zone. In the case of a
 read-only zone discovered at run-time, as indicated in the previous section.
 The size of the zone file is left unchanged from its last updated value.
 
+A zoned block device (e.g. an NVMe Zoned Namespace device) may have limits on
+the number of zones that can be active, that is, zones that are in the
+implicit open, explicit open or closed conditions.  This potential limitation
+translates into a risk for applications to see write IO errors due to this
+limit being exceeded if the zone of a file is not already active when a write
+request is issued by the user.
+
+To avoid these potential errors, the "explicit-open" mount option forces zones
+to be made active using an open zone command when a file is opened for writing
+for the first time. If the zone open command succeeds, the application is then
+guaranteed that write requests can be processed. Conversely, the
+"explicit-open" mount option will result in a zone close command being issued
+to the device on the last close() of a zone file if the zone is not full nor
+empty.
+
 Zonefs User Space Tools
 =======================
 
-- 
2.26.2


  parent reply	other threads:[~2020-09-09 10:26 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-09 10:26 [PATCH v2 0/3] zonefs: introduce -o " Johannes Thumshirn
2020-09-09 10:26 ` [PATCH v2 1/3] zonefs: introduce helper for zone management Johannes Thumshirn
2020-09-09 12:43   ` Damien Le Moal
2020-09-09 14:43     ` Johannes Thumshirn
2020-09-09 10:26 ` [PATCH v2 2/3] zonefs: open/close zone on file open/close Johannes Thumshirn
2020-09-09 12:50   ` Damien Le Moal
2020-09-09 10:26 ` Johannes Thumshirn [this message]
2020-09-09 12:52   ` [PATCH v2 3/3] zonefs: document the explicit-open mount option Damien Le Moal
2020-09-09 12:52 ` [PATCH v2 0/3] zonefs: introduce -o " Damien Le Moal
2020-09-09 14:43   ` Johannes Thumshirn

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