Merge tag 'libnvdimm-for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdim...

[linux-2.6-microblaze.git] / Documentation / filesystems / zonefs.rst

diff --git a/Documentation/filesystems/zonefs.rst b/Documentation/filesystems/zonefs.rst
index 6c18bc8..6b213fe 100644 (file)
--- 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
 =======================