Merge tag 'zonefs-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs

Pull zonefs updates from Damien Le Moal:
 "This improves zonefs open sequential file accounting and adds
  accounting for active sequential files to allow the user to handle the
  maximum number of active zones of an NVMe ZNS drive.

  sysfs attributes for both open and active sequential files are also
  added to facilitate access to this information from applications
  without resorting to inspecting the block device limits"

* tag 'zonefs-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs:
  documentation: zonefs: Document sysfs attributes
  documentation: zonefs: Cleanup the mount options section
  zonefs: Add active seq file accounting
  zonefs: Export open zone resource information through sysfs
  zonefs: Always do seq file write open accounting
  zonefs: Rename super block information fields
  zonefs: Fix management of open zones
  zonefs: Clear inode information flags on inode creation

1 files changed, 50 insertions, 2 deletions

diff --git a/Documentation/filesystems/zonefs.rst b/Documentation/filesystems/zonefs.rst
index 6b213fe9a33e..394b9f15dce0 100644
--- a/Documentation/filesystems/zonefs.rst
+++ b/Documentation/filesystems/zonefs.rst
@@ -306,8 +306,15 @@ Further notes:
 Mount options
 -------------
 
-zonefs define the "errors=<behavior>" mount option to allow the user to specify
-zonefs behavior in response to I/O errors, inode size inconsistencies or zone
+zonefs defines several mount options:
+* errors=<behavior>
+* explicit-open
+
+"errors=<behavior>" option
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The "errors=<behavior>" option mount option allows the user to specify zonefs
+behavior in response to I/O errors, inode size inconsistencies or zone
 condition changes. The defined behaviors are as follow:
 
 * remount-ro (default)
@@ -326,6 +333,9 @@ 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.
 
+"explicit-open" option
+~~~~~~~~~~~~~~~~~~~~~~
+
 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
@@ -341,6 +351,44 @@ guaranteed that write requests can be processed. Conversely, the
 to the device on the last close() of a zone file if the zone is not full nor
 empty.
 
+Runtime sysfs attributes
+------------------------
+
+zonefs defines several sysfs attributes for mounted devices.  All attributes
+are user readable and can be found in the directory /sys/fs/zonefs/<dev>/,
+where <dev> is the name of the mounted zoned block device.
+
+The attributes defined are as follows.
+
+* **max_wro_seq_files**:  This attribute reports the maximum number of
+  sequential zone files that can be open for writing.  This number corresponds
+  to the maximum number of explicitly or implicitly open zones that the device
+  supports.  A value of 0 means that the device has no limit and that any zone
+  (any file) can be open for writing and written at any time, regardless of the
+  state of other zones.  When the *explicit-open* mount option is used, zonefs
+  will fail any open() system call requesting to open a sequential zone file for
+  writing when the number of sequential zone files already open for writing has
+  reached the *max_wro_seq_files* limit.
+* **nr_wro_seq_files**:  This attribute reports the current number of sequential
+  zone files open for writing.  When the "explicit-open" mount option is used,
+  this number can never exceed *max_wro_seq_files*.  If the *explicit-open*
+  mount option is not used, the reported number can be greater than
+  *max_wro_seq_files*.  In such case, it is the responsibility of the
+  application to not write simultaneously more than *max_wro_seq_files*
+  sequential zone files.  Failure to do so can result in write errors.
+* **max_active_seq_files**:  This attribute reports the maximum number of
+  sequential zone files that are in an active state, that is, sequential zone
+  files that are partially writen (not empty nor full) or that have a zone that
+  is explicitly open (which happens only if the *explicit-open* mount option is
+  used).  This number is always equal to the maximum number of active zones that
+  the device supports.  A value of 0 means that the mounted device has no limit
+  on the number of sequential zone files that can be active.
+* **nr_active_seq_files**:  This attributes reports the current number of
+  sequential zone files that are active. If *max_active_seq_files* is not 0,
+  then the value of *nr_active_seq_files* can never exceed the value of
+  *nr_active_seq_files*, regardless of the use of the *explicit-open* mount
+  option.
+
 Zonefs User Space Tools
 =======================