Commit 31a644b3 authored by Damien Le Moal's avatar Damien Le Moal
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documentation: zonefs: Document sysfs attributes 



Document the max_wro_seq_files, nr_wro_seq_files, max_active_seq_files
and nr_active_seq_files sysfs attributes.

Signed-off-by: default avatarDamien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarHans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: default avatarSergey Shtylyov <s.shtylyov@omp.ru>
parent ae430388

Documentation/filesystems/zonefs.rst

+38 −0
Original line number Diff line number Diff line
@@ -351,6 +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

=======================