On 2011-09-11 07:51, Benny Halevy wrote:
> On 2011-09-10 10:41, Jim Rees wrote:
>> From: Peng Tao <bergwolf@xxxxxxxxx>
>
> Hi, I have a few comments inline below.
> Otherwise, the direction and the patch looks good.
>
>>
>> For layoutdriver io done functions, default workqueue is not a good place as
>> the code is executed in IO path. So add a pnfs private workqueue to handle
>> them.
>>
>> Also change block and object layout code to make use of this private
>> workqueue.
>>
>> Signed-off-by: Peng Tao <peng_tao@xxxxxxx>
>> Signed-off-by: Jim Rees <rees@xxxxxxxxx>
>> ---
>> fs/nfs/blocklayout/blocklayout.c | 17 ++++++++---
>> fs/nfs/objlayout/objio_osd.c | 8 ++++++
>> fs/nfs/objlayout/objlayout.c | 4 +-
>> fs/nfs/pnfs.c | 52 +++++++++++++++++++++++++++++++++++++-
>> fs/nfs/pnfs.h | 4 +++
>> 5 files changed, 77 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
>> index dc23833..51f70f0 100644
>> --- a/fs/nfs/blocklayout/blocklayout.c
>> +++ b/fs/nfs/blocklayout/blocklayout.c
>> @@ -228,7 +228,7 @@ bl_end_par_io_read(void *data)
>> struct nfs_read_data *rdata = data;
>>
>> INIT_WORK(&rdata->task.u.tk_work, bl_read_cleanup);
>> - schedule_work(&rdata->task.u.tk_work);
>> + pnfsiod_queue_work(&rdata->task.u.tk_work);
>> }
>>
>> /* We don't want normal .rpc_call_done callback used, so we replace it
>> @@ -418,7 +418,7 @@ static void bl_end_par_io_write(void *data)
>> wdata->task.tk_status = 0;
>> wdata->verf.committed = NFS_FILE_SYNC;
>> INIT_WORK(&wdata->task.u.tk_work, bl_write_cleanup);
>> - schedule_work(&wdata->task.u.tk_work);
>> + pnfsiod_queue_work(&wdata->task.u.tk_work);
>> }
>>
>> /* FIXME STUB - mark intersection of layout and page as bad, so is not
>> @@ -981,29 +981,35 @@ static int __init nfs4blocklayout_init(void)
>> if (ret)
>> goto out;
>>
>> + ret = pnfsiod_start();
>> + if (ret)
>> + goto out_remove;
>> +
>> init_waitqueue_head(&bl_wq);
>>
>> mnt = rpc_get_mount();
>> if (IS_ERR(mnt)) {
>> ret = PTR_ERR(mnt);
>> - goto out_remove;
>> + goto out_stop;
>> }
>>
>> ret = vfs_path_lookup(mnt->mnt_root,
>> mnt,
>> NFS_PIPE_DIRNAME, 0, &path);
>> if (ret)
>> - goto out_remove;
>> + goto out_stop;
>>
>> bl_device_pipe = rpc_mkpipe(path.dentry, "blocklayout", NULL,
>> &bl_upcall_ops, 0);
>> if (IS_ERR(bl_device_pipe)) {
>> ret = PTR_ERR(bl_device_pipe);
>> - goto out_remove;
>> + goto out_stop;
>> }
>> out:
>> return ret;
>>
>> +out_stop:
>> + pnfsiod_stop();
>> out_remove:
>> pnfs_unregister_layoutdriver(&blocklayout_type);
>> return ret;
>> @@ -1015,6 +1021,7 @@ static void __exit nfs4blocklayout_exit(void)
>> __func__);
>>
>> pnfs_unregister_layoutdriver(&blocklayout_type);
>> + pnfsiod_stop();
>> rpc_unlink(bl_device_pipe);
>> }
>>
>> diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
>> index d0cda12..f28013f 100644
>> --- a/fs/nfs/objlayout/objio_osd.c
>> +++ b/fs/nfs/objlayout/objio_osd.c
>> @@ -1042,7 +1042,14 @@ static int __init
>> objlayout_init(void)
>> {
>> int ret = pnfs_register_layoutdriver(&objlayout_type);
>> + if (ret)
>> + goto out;
>>
>> + ret = pnfsiod_start();
>> + if (ret)
>> + pnfs_unregister_layoutdriver(&objlayout_type);
>> +
>> +out:
Also, it makes more sense to init the workqueue before registering the
layout driver since it's a prerequisite.
>> if (ret)
>> printk(KERN_INFO
>> "%s: Registering OSD pNFS Layout Driver failed: error=%d\n",
>> @@ -1057,6 +1064,7 @@ static void __exit
>> objlayout_exit(void)
>> {
>> pnfs_unregister_layoutdriver(&objlayout_type);
>> + pnfsiod_stop();
>> printk(KERN_INFO "%s: Unregistered OSD pNFS Layout Driver\n",
>> __func__);
>> }
>> diff --git a/fs/nfs/objlayout/objlayout.c b/fs/nfs/objlayout/objlayout.c
>> index 1d06f8e..f7c6c21 100644
>> --- a/fs/nfs/objlayout/objlayout.c
>> +++ b/fs/nfs/objlayout/objlayout.c
>> @@ -305,7 +305,7 @@ objlayout_read_done(struct objlayout_io_state *state, ssize_t status, bool sync)
>> pnfs_ld_read_done(rdata);
>> else {
>> INIT_WORK(&rdata->task.u.tk_work, _rpc_read_complete);
>> - schedule_work(&rdata->task.u.tk_work);
>> + pnfsiod_queue_work(&rdata->task.u.tk_work);
>> }
>> }
>>
>> @@ -396,7 +396,7 @@ objlayout_write_done(struct objlayout_io_state *state, ssize_t status,
>> pnfs_ld_write_done(wdata);
>> else {
>> INIT_WORK(&wdata->task.u.tk_work, _rpc_write_complete);
>> - schedule_work(&wdata->task.u.tk_work);
>> + pnfsiod_queue_work(&wdata->task.u.tk_work);
>> }
>> }
>>
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index e550e88..5ac7a78 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -38,7 +38,7 @@
>> /* Locking:
>> *
>> * pnfs_spinlock:
>> - * protects pnfs_modules_tbl.
>> + * protects pnfs_modules_tbl, pnfsiod_workqueue and pnfsiod_users.
>> */
>> static DEFINE_SPINLOCK(pnfs_spinlock);
>>
>> @@ -47,6 +47,9 @@ static DEFINE_SPINLOCK(pnfs_spinlock);
>> */
>> static LIST_HEAD(pnfs_modules_tbl);
>>
>> +static struct workqueue_struct *pnfsiod_workqueue;
>> +static int pnfsiod_users = 0;
>
> There's no need to initialize static variables to zero.
>
>> +
>> /* Return the registered pnfs layout driver module matching given id */
>> static struct pnfs_layoutdriver_type *
>> find_pnfs_driver_locked(u32 id)
>> @@ -1478,3 +1481,50 @@ out:
>> dprintk("<-- %s status %d\n", __func__, status);
>> return status;
>> }
>> +
>> +/*
>> + * start up the pnfsiod workqueue
>> + */
>> +int pnfsiod_start(void)
>> +{
>> + struct workqueue_struct *wq;
>> + dprintk("RPC: creating workqueue pnfsiod\n");
>
> hmm, s/RPC/NFS/ this is not the RPC module any more :)
> looks like a cut'n'paste from rpciod_start...
>
>> + wq = alloc_workqueue("pnfsiod", WQ_MEM_RECLAIM, 0);
>> + if (wq == NULL)
>> + return -ENOMEM;
>> + spin_lock(&pnfs_spinlock);
>> + pnfsiod_users++;
>> + if (pnfsiod_workqueue == NULL) {
>> + pnfsiod_workqueue = wq;
>> + } else {
>> + destroy_workqueue(wq);
>> + }
>
> The curly braces in this statement are an overkill
> (and deviation from CodingStyle)
>
>> + spin_unlock(&pnfs_spinlock);
>> + return 0;
>
> although this way of accounting is ultimately simple
> it's wasteful and since we're not really expecting any concurrent
> calls to this function. I'd consider coding this it as follows:
>
> atomic_inc(&pnfsiod_users);
> if (pnfsiod_workqueue == NULL) {
> wq = alloc_workqueue("pnfsiod", WQ_MEM_RECLAIM, 0);
> if (wq == NULL)
sorry, we need to call nfsiod_stop here.
I'll send a SQUASHME patch with my proposed changes
to this one to make it clearer...
Benny
> return -ENOMEM;
> spin_lock(&pnfs_spinlock);
> if (pnfsiod_workqueue == NULL)
> pnfsiod_workqueue = wq;
> else
> destroy_workqueue(wq);
> spin_unlock(&pnfs_spinlock);
> }
>
> return 0;
>
>> +}
>> +EXPORT_SYMBOL_GPL(pnfsiod_start);
>> +
>> +/*
>> + * Destroy the pnfsiod workqueue
>> + */
>> +void pnfsiod_stop(void)
>> +{
>> + struct workqueue_struct *wq = NULL;
>> +
>> + spin_lock(&pnfs_spinlock);
>> + pnfsiod_users--;
>> + if (pnfsiod_users == 0) {
>> + wq = pnfsiod_workqueue;
>> + pnfsiod_workqueue = NULL;
>> + }
>> + spin_unlock(&pnfs_spinlock);
>> + if (wq)
>> + destroy_workqueue(wq);
>
> and continuing my proposal from above:
>
> if (atomic_dec_and_lock(&pnfsiod_users)) {
> wq = pnfsiod_workqueue;
> pnfsiod_workqueue = NULL;
> spin_unlock(&pnfs_spinlock);
> }
> if (wq)
> destroy_workqueue(wq);
>
> Benny
>
>> +}
>> +EXPORT_SYMBOL_GPL(pnfsiod_stop);
>> +
>> +void pnfsiod_queue_work(struct work_struct* work)
>> +{
>> + queue_work(pnfsiod_workqueue, work);
>> +}
>> +EXPORT_SYMBOL_GPL(pnfsiod_queue_work);
>> diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
>> index 01cbfd5..bc1eed5 100644
>> --- a/fs/nfs/pnfs.h
>> +++ b/fs/nfs/pnfs.h
>> @@ -165,6 +165,10 @@ extern int nfs4_proc_layoutget(struct nfs4_layoutget *lgp);
>> extern int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp);
>>
>> /* pnfs.c */
>> +int pnfsiod_start(void);
>> +void pnfsiod_stop(void);
>> +void pnfsiod_queue_work(struct work_struct* work);
>> +
>> void get_layout_hdr(struct pnfs_layout_hdr *lo);
>> void put_lseg(struct pnfs_layout_segment *lseg);
>>
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