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[Gluster-devel] QUOTA xlator (redesigned unlink accounting fops)

From: Angel
Subject: [Gluster-devel] QUOTA xlator (redesigned unlink accounting fops)
Date: Mon, 21 Jan 2008 14:38:07 +0100
User-agent: KMail/1.9.6 (enterprise 20070904.708012)

thanks for helping me

I still dont get all the picture but im trying...

firing two calls in one pass? I dont get it...

(several beers later...)

lets try 

1- I get called on quota_unlink (someone wants to unlink a file)


        struct stat *mybuf=calloc(...)           // I calloc a private  stat * 
        point frame->local to mybuf  // is that correct mybuf is owned now by 
me not posix-storage ahh??
        well lets dual fire downwards
                // WIND or UNWIND?? I never remember (my English need 

                STACK_WIND "statfs (statfs_cbk, unlink_requested_file)"  // Its 
just pseudocode!!
                STACK_WIND "unlink(unlink_cbk, unlink_requested_file)"  


"They are exec in order so..." 

2- I get called first on quota_statfs_cbk

        if (frame->local is NULL) // do normal callback unwinding..
                procced to upper xlator stack unwinds..

        } else { // im using statfs for private affairs...

                mybuf = frame->local                   // recover mybuf , hey 
you this is mine!!
                frame->local= NULL                     // dont trash thigs 
                memcopy stat buf returned to mybuf
                mybuf = memcpy(buf)                 // later unlink_cbk will 
need this

                no one but me expected this callback, dont unwind stack call


3- quota_unlink_cbk(...)
                                                             // Ok! the file 
was deleted??
gives me a gift
        mybuf = frame->local                    // recover stat mybuf
        frame->local = NULL                     // sanitize
        if ( mybuf->hardlinks >= 1) {         // Ok, Ok file was hardlinked, 
better luck next time
        } else {                                          // Hey whats this? 
file was not linked!! we recovered storage 
        free (mybuf)                                 // thats all folks!!  see 
you next unlik...
        STACK_UNWINDS(...)                 // go, go with your mamma


Its thats ok? i got the idea? 


El Lunes, 21 de Enero de 2008 Anand Avati escribió:
> Angel,
>  Thanks for kickstarting :) Some comments -
> 1. Storing stat from pre_unlink_stat_cbk into frame->local is not right
> since.
> 2. Instead of having a pre_unlink_stat and then subtracting (after fixing
> the storage of stat), why not have a post_unlink_statfs() ? That sounds a
> lot neater implementation. It also guards against hardlinks getting wrongly
> calculated twice. You can also improve the performance by pipelining unlink
> and statfs one after another without waiting for the callback from the other
> (the order of two stack_winds from the same thread will guarantee the same
> order of execution at posix (if they both are headed towards the same
> storage/posix) unless the calls are a mix of file/non-file (in this case
> both are non-file, so order is guaranteed).
> 3. it would also be convinient if you 'unimplement' the remaining fops which
> are copied from trace.
> 4. do you have any thoughts on per-user or per-dir? If so I would like to
> discuss as we are discussing internally with a few algos for doing the most
> efficient per-dir quota.
> thanks,
> avati
> 2008/1/20, Angel <address@hidden>:
> >

Clist UAH

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