Re: [PATCH 1/1] SQUASHME pnfs-submit: replace layoutcommit_ctx with rpc_cred

[Benny Halevy <bhalevy@panasas.com>]

On May. 25, 2010, 7:07 +0300, Benny Halevy <bhalevy@panasas.com> wrote:
> On May. 24, 2010, 21:28 +0300, andros@netapp.com wrote:
>> From: Andy Adamson <andros@netapp.com>
>>
>> Taking a reference on the nfs_open_context to signal that a layoutcommit is
>> needed is problematic because the last reference to the context triggers a
>> close (nfs_release).  But, if the layout holds a reference on the
>> nfs_open_context, then close will not be triggered.
>>
>> Since we only use the rpc credential from the layoutcommit_ctx, replace the
>> layoutcommit_ctx with the rpc_cred.
>>
>> Hold a reference on the rpc_cred until the layoutcommit rpc returns.
>>
>> If the layoutdriver fails to setup the layoutcommit, clear the layoutcommit
>> properties and put the credential.
>>
>> Signed-off-by: Andy Adamson <andros@netapp.com>
>> ---
>>  fs/nfs/inode.c            |    4 ++--
>>  fs/nfs/nfs4state.c        |    2 +-
>>  fs/nfs/pnfs.c             |   42 +++++++++++++++++-------------------------
>>  fs/nfs/write.c            |    2 +-
>>  include/linux/nfs4_pnfs.h |    6 ++++++
>>  include/linux/nfs_fs.h    |    3 +--
>>  include/linux/pnfs_xdr.h  |    1 -
>>  7 files changed, 28 insertions(+), 32 deletions(-)
>>
>> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
>> index 7fd33d9..2b8e8e6 100644
>> --- a/fs/nfs/inode.c
>> +++ b/fs/nfs/inode.c
>> @@ -1110,7 +1110,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
>>  	/*
>>  	 * file needs layout commit, server attributes may be stale
>>  	 */
>> -	if (nfsi->layoutcommit_ctx && nfsi->change_attr >= fattr->change_attr) {
>> +	if (do_layoutcommit(nfsi) && nfsi->change_attr >= fattr->change_attr) {
> 
> Andy, the patch looks good overall, thanks!
> One nit though: mind if I rename "do_layoutcommit" which reads as if it actually performs
> the layoutcommit call to "layoutcommit_needed"?
> 
> Benny
> 

Committed at pnfs-all-2.6.34-2010-05-25
(with the renamed function)

Thanks!

Benny

>>  		dprintk("NFS: %s: layoutcommit is needed for file %s/%ld\n",
>>  			__func__, inode->i_sb->s_id, inode->i_ino);
>>  		return 0;
>> @@ -1331,7 +1331,7 @@ static void pnfs_alloc_init_inode(struct nfs_inode *nfsi)
>>  	nfsi->pnfs_layout_state = 0;
>>  	memset(&nfsi->layout.stateid, 0, NFS4_STATEID_SIZE);
>>  	nfsi->layout.roc_iomode = 0;
>> -	nfsi->layoutcommit_ctx = NULL;
>> +	nfsi->lo_cred = NULL;
>>  	nfsi->pnfs_write_begin_pos = 0;
>>  	nfsi->pnfs_write_end_pos = 0;
>>  #endif /* CONFIG_NFS_V4_1 */
>> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
>> index d145de1..bf03fde 100644
>> --- a/fs/nfs/nfs4state.c
>> +++ b/fs/nfs/nfs4state.c
>> @@ -589,7 +589,7 @@ static void __nfs4_close(struct path *path, struct nfs4_state *state, fmode_t fm
>>  #ifdef CONFIG_NFS_V4_1
>>  		struct nfs_inode *nfsi = NFS_I(state->inode);
>>  
>> -		if (nfsi->layoutcommit_ctx)
>> +		if (do_layoutcommit(nfsi))
>>  			pnfs_layoutcommit_inode(state->inode, wait);
>>  		if (has_layout(nfsi) && nfsi->layout.roc_iomode) {
>>  			struct nfs4_pnfs_layout_segment range;
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index 20285bc..ee530c8 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -145,21 +145,19 @@ find_pnfs(u32 id, struct pnfs_module **module) {
>>  	return 0;
>>  }
>>  
>> -/* Set context to indicate we require a layoutcommit
>> +/* Set lo_cred to indicate we require a layoutcommit
>>   * If we don't even have a layout, we don't need to commit it.
>>   */
>>  void
>>  pnfs_need_layoutcommit(struct nfs_inode *nfsi, struct nfs_open_context *ctx)
>>  {
>> -	dprintk("%s: has_layout=%d layoutcommit_ctx=%p ctx=%p\n", __func__,
>> -		has_layout(nfsi), nfsi->layoutcommit_ctx, ctx);
>> +	dprintk("%s: has_layout=%d ctx=%p\n", __func__, has_layout(nfsi), ctx);
>>  	spin_lock(&nfsi->lo_lock);
>> -	if (has_layout(nfsi) && !nfsi->layoutcommit_ctx) {
>> -		nfsi->layoutcommit_ctx = get_nfs_open_context(ctx);
>> +	if (has_layout(nfsi) && !do_layoutcommit(nfsi)) {
>> +		nfsi->lo_cred = get_rpccred(ctx->state->owner->so_cred);
>>  		nfsi->change_attr++;
>>  		spin_unlock(&nfsi->lo_lock);
>> -		dprintk("%s: Set layoutcommit_ctx=%p\n", __func__,
>> -			nfsi->layoutcommit_ctx);
>> +		dprintk("%s: Set layoutcommit\n", __func__);
>>  		return;
>>  	}
>>  	spin_unlock(&nfsi->lo_lock);
>> @@ -755,7 +753,7 @@ _pnfs_return_layout(struct inode *ino, struct nfs4_pnfs_layout_segment *range,
>>  				!pnfs_return_layout_barrier(nfsi, &arg));
>>  		}
>>  
>> -		if (nfsi->layoutcommit_ctx) {
>> +		if (do_layoutcommit(nfsi)) {
>>  			status = pnfs_layoutcommit_inode(ino, wait);
>>  			if (status) {
>>  				dprintk("%s: layoutcommit failed, status=%d. "
>> @@ -1910,16 +1908,9 @@ pnfs_layoutcommit_done(struct pnfs_layoutcommit_data *data)
>>  
>>  	dprintk("%s: (status %d)\n", __func__, data->status);
>>  
>> -	/* TODO: For now, set an error in the open context (just like
>> -	 * if a commit failed) We may want to do more, much more, like
>> -	 * replay all writes through the NFSv4
>> -	 * server, or something.
>> -	 */
>> -	if (data->status < 0) {
>> +	if (data->status < 0)
>>  		printk(KERN_ERR "%s, Layoutcommit Failed! = %d\n",
>>  		       __func__, data->status);
>> -		data->ctx->error = data->status;
>> -	}
>>  
>>  	/* TODO: Maybe we should avoid this by allowing the layout driver
>>  	 * to directly xdr its layout on the wire.
>> @@ -1929,9 +1920,7 @@ pnfs_layoutcommit_done(struct pnfs_layoutcommit_data *data)
>>  							&nfsi->layout,
>>  							&data->args,
>>  							data->status);
>> -
>> -	/* release the open_context acquired in pnfs_writeback_done */
>> -	put_nfs_open_context(data->ctx);
>> +	put_rpccred(data->cred);
>>  }
>>  
>>  /*
>> @@ -1995,24 +1984,27 @@ pnfs_layoutcommit_inode(struct inode *inode, int sync)
>>  		return -ENOMEM;
>>  
>>  	spin_lock(&nfsi->lo_lock);
>> -	if (!nfsi->layoutcommit_ctx)
>> +	if (!do_layoutcommit(nfsi))
>>  		goto out_unlock;
>>  
>>  	data->args.inode = inode;
>> -	data->cred  = nfsi->layoutcommit_ctx->cred;
>> -	data->ctx = nfsi->layoutcommit_ctx;
>> +	data->cred = nfsi->lo_cred;
>>  
>>  	/* Set up layout commit args*/
>>  	status = pnfs_layoutcommit_setup(data, sync);
>> -	if (status)
>> -		goto out_unlock;
>>  
>>  	/* Clear layoutcommit properties in the inode so
>>  	 * new lc info can be generated
>>  	 */
>>  	nfsi->pnfs_write_begin_pos = 0;
>>  	nfsi->pnfs_write_end_pos = 0;
>> -	nfsi->layoutcommit_ctx = NULL;
>> +	nfsi->lo_cred = NULL;
>> +
>> +	if (status) {
>> +		/* The layout driver failed to setup the layoutcommit */
>> +		put_rpccred(data->cred);
>> +		goto out_unlock;
>> +	}
>>  
>>  	/* release lock on pnfs layoutcommit attrs */
>>  	spin_unlock(&nfsi->lo_lock);
>> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
>> index a4c95a0..2c1918e 100644
>> --- a/fs/nfs/write.c
>> +++ b/fs/nfs/write.c
>> @@ -1490,7 +1490,7 @@ static int nfs_commit_inode(struct inode *inode, int how)
>>  					nfs_wait_bit_killable,
>>  					TASK_KILLABLE);
>>  #ifdef CONFIG_NFS_V4_1
>> -		if (may_wait && NFS_I(inode)->layoutcommit_ctx) {
>> +		if (may_wait && do_layoutcommit(NFS_I(inode))) {
>>  			error = pnfs_layoutcommit_inode(inode, 1);
>>  			if (error < 0)
>>  				return error;
>> diff --git a/include/linux/nfs4_pnfs.h b/include/linux/nfs4_pnfs.h
>> index 4d47b48..c9ef43e 100644
>> --- a/include/linux/nfs4_pnfs.h
>> +++ b/include/linux/nfs4_pnfs.h
>> @@ -80,6 +80,12 @@ has_layout(struct nfs_inode *nfsi)
>>  	return nfsi->layout.ld_data != NULL;
>>  }
>>  
>> +static inline bool
>> +do_layoutcommit(struct nfs_inode *nfsi)
>> +{
>> +	return nfsi->lo_cred != NULL;
>> +}
>> +
>>  #endif /* CONFIG_NFS_V4_1 */
>>  
>>  struct pnfs_layout_segment {
>> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
>> index 98a8dc0..478b00c 100644
>> --- a/include/linux/nfs_fs.h
>> +++ b/include/linux/nfs_fs.h
>> @@ -203,11 +203,10 @@ struct nfs_inode {
>>  #define NFS_INO_RW_LAYOUT_FAILED 1 	/* get rw layout failed stop trying */
>>  #define NFS_INO_LAYOUT_ALLOC     2	/* bit lock for layout allocation */
>>  	time_t pnfs_layout_suspend;
>> +	struct rpc_cred		*lo_cred; /* layoutcommit credential */
>>  	wait_queue_head_t lo_waitq;
>>  	spinlock_t lo_lock;
>>  	struct pnfs_layout_type layout;
>> -	/* use rpc_creds in this open_context to send LAYOUTCOMMIT to MDS */
>> -	struct nfs_open_context *layoutcommit_ctx;
>>  	/* DH: These vars keep track of the maximum write range
>>  	 * so the values can be used for layoutcommit.
>>  	 */
>> diff --git a/include/linux/pnfs_xdr.h b/include/linux/pnfs_xdr.h
>> index a0bf341..154b04e 100644
>> --- a/include/linux/pnfs_xdr.h
>> +++ b/include/linux/pnfs_xdr.h
>> @@ -86,7 +86,6 @@ struct pnfs_layoutcommit_data {
>>  	bool is_sync;
>>  	struct rpc_cred *cred;
>>  	struct nfs_fattr fattr;
>> -	struct nfs_open_context *ctx;
>>  	struct pnfs_layoutcommit_arg args;
>>  	struct pnfs_layoutcommit_res res;
>>  	int status;
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