Re: [PATCH v2] ext4: add sysfs entry showing whether the fs contains errors

[Theodore Ts'o <tytso@mit.edu>]

On Wed, May 07, 2014 at 05:35:54PM +0200, Lukáš Czerner wrote:
> 
> I tried to find sysfs guidelines but I can not see any in
> Documentation speaking about the contents of the files.
> 
> What are the guidelines then ?

Documentation/filesystems/sysfs.txt:

   Attributes can be exported for kobjects in the form of regular
   files in the filesystem. Sysfs forwards file I/O operations to
   methods defined for the attributes, providing a means to read and
   write kernel attributes.

   Attributes should be ASCII text files, preferably with only one value
   per file. It is noted that it may not be efficient to contain only one
   value per file, so it is socially acceptable to express an array of
   values of the same type. 

I don't remember that last sentence; it was apparently added since the
last time I've looked at it.  Originally, the requirement that each
sysfs file (which was supposed to be an kobject attribute) was
required to be a single value.  Now there's an escape hatch for
"efficiency", which is nice....

> So you're suggesting to have three sysfs files ?
> 
> errors_count
> first_error_time
> last_error_time

Yes, that's what I was suggesting.

						- Ted
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