[lustre-discuss] llapi documentation

John Bauer bauerj at iodoctors.com
Wed Jun 15 12:37:38 PDT 2022 

While sitting stuck in traffic in a torrential downpour I figured out 3 
of my 4 questions. The only remain question:  Can something be done 
about the prints coming from  the llapi_get_pool...() functions?

llapi_get_poollist() generates a print of:*Pools from nbp17:*

llapi_get_poolmembers() generates a print of:*Pool: nbp17.1_ssd*

John

On 6/15/2022 7:53 AM, lustre-discuss-request at lists.lustre.org wrote:
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>     1. Re: llapi documentation (Andreas Dilger)
>     2. Re: llapi documentation (John Bauer)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 15 Jun 2022 07:08:58 +0000
> From: Andreas Dilger<adilger at whamcloud.com>
> To: John Bauer<bauerj at iodoctors.com>
> Cc:"lustre-discuss at lists.lustre.org"
> 	<lustre-discuss at lists.lustre.org>
> Subject: Re: [lustre-discuss] llapi documentation
> Message-ID:<19C08E40-B54A-485D-99E8-9258866085E0 at ddn.com>
> Content-Type: text/plain; charset="us-ascii"
>
> On Jun 14, 2022, at 05:32, John Bauer <bauerj at iodoctors.com<mailto:bauerj at iodoctors.com>> wrote:
>
> I have had little success in my search for documentation on pool functions in llapi. I've looked in:
>
> https://wiki.lustre.org/PFL2_High_Level_Design
>
> https://doc.lustre.org/lustre_manual.xhtml#managingstripingfreespace
>
>
> I'm looking for info on llapi_get_poollist() and llapi_get_poolmembers().  I've found the prototype in /usr/include/lustre/lustreapi.h, but that's about it.
>
> Can anyone point me to some documentation?
>
> it looks like there aren't man pages for these functions, just the function comment blocks
> in the code, and their usage internally:
>
> /**
>   * Get the list of pools in a filesystem.
>   * \param name        filesystem name or path
>   * \param poollist    caller-allocated array of char*
>   * \param list_size   size of the poollist array
>   * \param buffer      caller-allocated buffer for storing pool names
>   * \param buffer_size size of the buffer
>   *
>   * \return number of pools retrieved for this filesystem
>   * \retval -error failure
>   */
> int llapi_get_poollist(const char *name, char **poollist, int list_size,
>                         char *buffer, int buffer_size)
>
> /**
>   * Get the list of pool members.
>   * \param poolname    string of format \<fsname\>.\<poolname\>
>   * \param members     caller-allocated array of char*
>   * \param list_size   size of the members array
>   * \param buffer      caller-allocated buffer for storing OST names
>   * \param buffer_size size of the buffer
>   *
>   * \return number of members retrieved for this pool
>   * \retval -error failure
>   */
> int llapi_get_poolmembers(const char *poolname, char **members,
>                            int list_size, char *buffer, int buffer_size)
>
> Patches to add llapi_get_poollist.3 and llapi_get_poolmembers.3 (and related) man
> pages welcome. The pool related functions should probably be moved into a new
> liblustreapi_pool.c file to reduce the size of liblustreapi.c.
>
> Cheers, Andreas
> --
> Andreas Dilger
> Lustre Principal Architect
> Whamcloud
>
>
>
>
>
>
>
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> Message: 2
> Date: Wed, 15 Jun 2022 07:56:40 -0500
> From: John Bauer<bauerj at iodoctors.com>
> To: Andreas Dilger<adilger at whamcloud.com>
> Cc:"lustre-discuss at lists.lustre.org"
> 	<lustre-discuss at lists.lustre.org>
> Subject: Re: [lustre-discuss] llapi documentation
> Message-ID:<8b437470-1f49-1535-94f2-8492956a4af8 at iodoctors.com>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Andreas,
>
> Thanks for the info.? It got me a lot farther down the road. A few comments:
>
> 1)? It appears that the values returned in the poollist argument to
> llapi_get_poollist() are temporary.? I used the values in
>
> poollist in the call to llapi_get_poolmembers( poollist[i],...). Works
> great on the first call to get_poolmembers(), but subsequent calls
>
> fail and it appears the poollist has been overwritten.? If I make my own
> copy of the strings in poollist before calling get_poolmembers,
> everythings works well.
>
> If this is indeed the case, it should be noted.
>
> 2)? There are prints to stdout or stderr resulting from calls to these
> llapi functions.
>
> llapi_get_poollist generates a print of:Pools from nbp17:
>
> llapi_get_poolmembers generates a print of:Pool: nbp17.1_ssd
>
> Seems undesirable to have llapi doing unrequested prints.
>
> 3)? What is the buffer argument good for ( last argument for each of the
> functions )?? It appears to be populated with the first value in
>
> in the array.
>
> 4)? Here is output from my test program.? There are 10 poolNames.? All
> works great until I get to the pool that has 64 members ( which I
>
> know from other paths ).? The 2nd argument to llapi_get_poolmembers() is
> a 'char *poolMembers[256]'.? Plenty of room, but the call fails
>
> with a return value of -75.? Why?
>
> Pools from nbp17:
> poollist_get() nPool=10 buffer=nbp17.1_hdd
> Pool: nbp17.1_hdd
> poollist_get() poolNames[0]=nbp17.1_hdd 8 members buffer=nbp17-OST0000_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[0]=nbp17-OST0000_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[1]=nbp17-OST0001_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[2]=nbp17-OST0002_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[3]=nbp17-OST0003_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[4]=nbp17-OST0004_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[5]=nbp17-OST0005_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[6]=nbp17-OST0006_UUID
> poollist_get()?????? poolNames[0]=nbp17.1_hdd members[7]=nbp17-OST0007_UUID
> Pool: nbp17.1_ssd
> poollist_get() poolNames[1]=nbp17.1_ssd 8 members buffer=nbp17-OST0064_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[0]=nbp17-OST0064_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[1]=nbp17-OST0065_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[2]=nbp17-OST0066_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[3]=nbp17-OST0067_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[4]=nbp17-OST0068_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[5]=nbp17-OST0069_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[6]=nbp17-OST006a_UUID
> poollist_get()?????? poolNames[1]=nbp17.1_ssd members[7]=nbp17-OST006b_UUID
> Pool: nbp17.2_hdd
> poollist_get() poolNames[2]=nbp17.2_hdd 8 members buffer=nbp17-OST0008_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[0]=nbp17-OST0008_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[1]=nbp17-OST0009_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[2]=nbp17-OST000a_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[3]=nbp17-OST000b_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[4]=nbp17-OST000c_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[5]=nbp17-OST000d_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[6]=nbp17-OST000e_UUID
> poollist_get()?????? poolNames[2]=nbp17.2_hdd members[7]=nbp17-OST000f_UUID
> Pool: nbp17.2_ssd
> poollist_get() poolNames[3]=nbp17.2_ssd 8 members buffer=nbp17-OST006c_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[0]=nbp17-OST006c_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[1]=nbp17-OST006d_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[2]=nbp17-OST006e_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[3]=nbp17-OST006f_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[4]=nbp17-OST0070_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[5]=nbp17-OST0071_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[6]=nbp17-OST0072_UUID
> poollist_get()?????? poolNames[3]=nbp17.2_ssd members[7]=nbp17-OST0073_UUID
> Pool: nbp17.3_hdd
> poollist_get() poolNames[4]=nbp17.3_hdd 8 members buffer=nbp17-OST0010_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[0]=nbp17-OST0010_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[1]=nbp17-OST0011_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[2]=nbp17-OST0012_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[3]=nbp17-OST0013_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[4]=nbp17-OST0014_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[5]=nbp17-OST0015_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[6]=nbp17-OST0016_UUID
> poollist_get()?????? poolNames[4]=nbp17.3_hdd members[7]=nbp17-OST0017_UUID
> Pool: nbp17.3_ssd
> poollist_get() poolNames[5]=nbp17.3_ssd 8 members buffer=nbp17-OST0074_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[0]=nbp17-OST0074_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[1]=nbp17-OST0075_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[2]=nbp17-OST0076_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[3]=nbp17-OST0077_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[4]=nbp17-OST0078_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[5]=nbp17-OST0079_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[6]=nbp17-OST007a_UUID
> poollist_get()?????? poolNames[5]=nbp17.3_ssd members[7]=nbp17-OST007b_UUID
> Pool: nbp17.4_hdd
> poollist_get() poolNames[6]=nbp17.4_hdd 8 members buffer=nbp17-OST0018_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[0]=nbp17-OST0018_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[1]=nbp17-OST0019_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[2]=nbp17-OST001a_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[3]=nbp17-OST001b_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[4]=nbp17-OST001c_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[5]=nbp17-OST001d_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[6]=nbp17-OST001e_UUID
> poollist_get()?????? poolNames[6]=nbp17.4_hdd members[7]=nbp17-OST001f_UUID
> Pool: nbp17.4_ssd
> poollist_get() poolNames[7]=nbp17.4_ssd 8 members buffer=nbp17-OST007c_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[0]=nbp17-OST007c_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[1]=nbp17-OST007d_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[2]=nbp17-OST007e_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[3]=nbp17-OST007f_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[4]=nbp17-OST0080_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[5]=nbp17-OST0081_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[6]=nbp17-OST0082_UUID
> poollist_get()?????? poolNames[7]=nbp17.4_ssd members[7]=nbp17-OST0083_UUID
> Pool: nbp17.hdd-pool
> poollist_get() poolNames[8]=nbp17.hdd-pool -75 members
> buffer=nbp17-OST0000_UUID
> Pool: nbp17.ssd-pool
> poollist_get() poolNames[9]=nbp17.ssd-pool -75 members
> buffer=nbp17-OST0064_UUID
>
> John
>
> On 6/15/22 02:08, Andreas Dilger wrote:
>> On Jun 14, 2022, at 05:32, John Bauer<bauerj at iodoctors.com>  wrote:
>>> I have had little success in my search for documentation on pool
>>> functions in llapi. I've looked in:
>>>
>>> https://wiki.lustre.org/PFL2_High_Level_Design
>>>
>>> https://doc.lustre.org/lustre_manual.xhtml#managingstripingfreespace
>>>
>>>
>>> I'm looking for info on llapi_get_poollist() and
>>> llapi_get_poolmembers().? I've found the prototype in
>>> /usr/include/lustre/lustreapi.h, but that's about it.
>>>
>>> Can anyone point me to some documentation?
>> it looks like there aren't man pages for these functions, just the
>> function comment blocks
>> in the code, and their usage internally:
>>
>> /**
>> ?* Get the list of pools in a filesystem.
>> ?* \param name? ? ? ??filesystem name or path
>> ?* \param poollist? ??caller-allocated array of char*
>> ?* \param list_size???size of the poollist array
>> ?* \param buffer? ? ??caller-allocated buffer for storing pool names
>> ?* \param buffer_size size of the buffer
>> ?*
>> ?* \return number of pools retrieved for this filesystem
>> ?* \retval -error failure
>> ?*/
>> int?llapi_get_poollist(const?char?*name,?char?**poollist,?int?list_size,
>> ? ? ? ? ? ? ? ? ? ? ? ?char?*buffer,?int?buffer_size)
>>
>> /**
>> ?* Get the list of pool members.
>> ?* \param poolname? ??string of format \<fsname\>.\<poolname\>
>> ?* \param members?? ??caller-allocated array of char*
>> ?* \param list_size???size of the members array
>> ?* \param buffer? ? ??caller-allocated buffer for storing OST names
>> ?* \param buffer_size size of the buffer
>> ?*
>> ?* \return number of members retrieved for this pool
>> ?* \retval -error failure
>> ?*/
>> int?llapi_get_poolmembers(const?char?*poolname,?char?**members,
>> ??int?list_size,?char?*buffer,?int?buffer_size)
>>
>> Patches to add?llapi_get_poollist.3 and llapi_get_poolmembers.3 (and
>> related) man
>> pages welcome. The pool related functions should probably be moved
>> into a new
>> liblustreapi_pool.c file to reduce the size of liblustreapi.c.
>>
>> Cheers, Andreas
>> --
>> Andreas Dilger
>> Lustre?Principal Architect
>> Whamcloud
>>
>>
>>
>>
>>
>>
>>
> On 6/15/22 02:08, Andreas Dilger wrote:
>> On Jun 14, 2022, at 05:32, John Bauer<bauerj at iodoctors.com>  wrote:
>>> I have had little success in my search for documentation on pool
>>> functions in llapi. I've looked in:
>>>
>>> https://wiki.lustre.org/PFL2_High_Level_Design
>>>
>>> https://doc.lustre.org/lustre_manual.xhtml#managingstripingfreespace
>>>
>>>
>>> I'm looking for info on llapi_get_poollist() and
>>> llapi_get_poolmembers().? I've found the prototype in
>>> /usr/include/lustre/lustreapi.h, but that's about it.
>>>
>>> Can anyone point me to some documentation?
>> it looks like there aren't man pages for these functions, just the
>> function comment blocks
>> in the code, and their usage internally:
>>
>> /**
>> ?* Get the list of pools in a filesystem.
>> ?* \param name? ? ? ??filesystem name or path
>> ?* \param poollist? ??caller-allocated array of char*
>> ?* \param list_size???size of the poollist array
>> ?* \param buffer? ? ??caller-allocated buffer for storing pool names
>> ?* \param buffer_size size of the buffer
>> ?*
>> ?* \return number of pools retrieved for this filesystem
>> ?* \retval -error failure
>> ?*/
>> int?llapi_get_poollist(const?char?*name,?char?**poollist,?int?list_size,
>> ? ? ? ? ? ? ? ? ? ? ? ?char?*buffer,?int?buffer_size)
>>
>> /**
>> ?* Get the list of pool members.
>> ?* \param poolname? ??string of format \<fsname\>.\<poolname\>
>> ?* \param members?? ??caller-allocated array of char*
>> ?* \param list_size???size of the members array
>> ?* \param buffer? ? ??caller-allocated buffer for storing OST names
>> ?* \param buffer_size size of the buffer
>> ?*
>> ?* \return number of members retrieved for this pool
>> ?* \retval -error failure
>> ?*/
>> int?llapi_get_poolmembers(const?char?*poolname,?char?**members,
>> ??int?list_size,?char?*buffer,?int?buffer_size)
>>
>> Patches to add?llapi_get_poollist.3 and llapi_get_poolmembers.3 (and
>> related) man
>> pages welcome. The pool related functions should probably be moved
>> into a new
>> liblustreapi_pool.c file to reduce the size of liblustreapi.c.
>>
>> Cheers, Andreas
>> --
>> Andreas Dilger
>> Lustre?Principal Architect
>> Whamcloud
>>
>>
>>
>>
>>
>>
>>
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