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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: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
This commit is contained in:
Damien Le Moal 2022-04-18 09:32:57 +09:00
parent ae43038866
commit 31a644b3c2
1 changed files with 38 additions and 0 deletions
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Documentation/filesystems/zonefs.rst
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@ -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
=======================