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Message-ID: <8708e2e4-b9e9-45a7-8aa5-2f06234d3ae2@oracle.com>
Date: Mon, 26 Aug 2024 08:31:07 -0700
From: Dai Ngo <dai.ngo@...cle.com>
To: Jeff Layton <jlayton@...nel.org>, Chuck Lever <chuck.lever@...cle.com>,
        Neil Brown <neilb@...e.de>, Olga Kornievskaia <kolga@...app.com>,
        Tom Talpey <tom@...pey.com>, Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] fs/nfsd: fix update of inode attrs in CB_GETATTR


On 8/24/24 5:46 AM, Jeff Layton wrote:
> Currently, we copy the mtime and ctime to the in-core inode and then
> mark the inode dirty. This is fine for certain types of filesystems, but
> not all. Some require a real setattr to properly change these values
> (e.g. ceph or reexported NFS).
>
> Fix this code to call notify_change() instead, which is the proper way
> to effect a setattr. There is one problem though:
>
> In this case, the client is holding a write delegation and has sent us
> attributes to update our cache. We don't want to break the delegation
> for this since that would defeat the purpose.

I think this won't happen with NFS since nfsd_breaker_owns_lease detects
its own lease and won't break the delegation.

-Dai

>   Add a new ATTR_DELEG flag
> that makes notify_change bypass the try_break_deleg call.
>
> Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
> ---
> One more CB_GETATTR fix. This one involves a little change at the VFS
> layer to avoid breaking the delegation.
>
> Christian, unless you have objections, this should probably go in
> via Chuck's tree as this patch depends on a nfsd patch [1] that I sent
> yesterday. An A-b or R-b would be welcome though.
>
> [1]: https://lore.kernel.org/linux-nfs/20240823-nfsd-fixes-v1-1-fc99aa16f6a0@kernel.org/T/#u
> ---
>   fs/attr.c           |  9 ++++++---
>   fs/nfsd/nfs4state.c | 18 +++++++++++++-----
>   fs/nfsd/nfs4xdr.c   |  2 +-
>   fs/nfsd/state.h     |  2 +-
>   include/linux/fs.h  |  1 +
>   5 files changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/fs/attr.c b/fs/attr.c
> index 960a310581eb..a40a2fb406f0 100644
> --- a/fs/attr.c
> +++ b/fs/attr.c
> @@ -489,9 +489,12 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
>   	error = security_inode_setattr(idmap, dentry, attr);
>   	if (error)
>   		return error;
> -	error = try_break_deleg(inode, delegated_inode);
> -	if (error)
> -		return error;
> +
> +	if (!(ia_valid & ATTR_DELEG)) {
> +		error = try_break_deleg(inode, delegated_inode);
> +		if (error)
> +			return error;
> +	}
>   
>   	if (inode->i_op->setattr)
>   		error = inode->i_op->setattr(idmap, dentry, attr);
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index dafff707e23a..e0e3d3ca0d45 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -8815,7 +8815,7 @@ nfsd4_get_writestateid(struct nfsd4_compound_state *cstate,
>   /**
>    * nfsd4_deleg_getattr_conflict - Recall if GETATTR causes conflict
>    * @rqstp: RPC transaction context
> - * @inode: file to be checked for a conflict
> + * @dentry: dentry of inode to be checked for a conflict
>    * @modified: return true if file was modified
>    * @size: new size of file if modified is true
>    *
> @@ -8830,7 +8830,7 @@ nfsd4_get_writestateid(struct nfsd4_compound_state *cstate,
>    * code is returned.
>    */
>   __be32
> -nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
> +nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
>   				bool *modified, u64 *size)
>   {
>   	__be32 status;
> @@ -8840,6 +8840,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
>   	struct nfs4_delegation *dp;
>   	struct iattr attrs;
>   	struct nfs4_cb_fattr *ncf;
> +	struct inode *inode = d_inode(dentry);
>   
>   	*modified = false;
>   	ctx = locks_inode_context(inode);
> @@ -8887,15 +8888,22 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
>   					ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
>   				ncf->ncf_file_modified = true;
>   			if (ncf->ncf_file_modified) {
> +				int err;
> +
>   				/*
>   				 * Per section 10.4.3 of RFC 8881, the server would
>   				 * not update the file's metadata with the client's
>   				 * modified size
>   				 */
>   				attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
> -				attrs.ia_valid = ATTR_MTIME | ATTR_CTIME;
> -				setattr_copy(&nop_mnt_idmap, inode, &attrs);
> -				mark_inode_dirty(inode);
> +				attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
> +				inode_lock(inode);
> +				err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
> +				inode_unlock(inode);
> +				if (err) {
> +					nfs4_put_stid(&dp->dl_stid);
> +					return nfserrno(err);
> +				}
>   				ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
>   				*size = ncf->ncf_cur_fsize;
>   				*modified = true;
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 43ccf6119cf1..97f583777972 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3565,7 +3565,7 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
>   	}
>   	args.size = 0;
>   	if (attrmask[0] & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
> -		status = nfsd4_deleg_getattr_conflict(rqstp, d_inode(dentry),
> +		status = nfsd4_deleg_getattr_conflict(rqstp, dentry,
>   					&file_modified, &size);
>   		if (status)
>   			goto out;
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index ffc217099d19..ec4559ecd193 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -781,5 +781,5 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
>   }
>   
>   extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
> -		struct inode *inode, bool *file_modified, u64 *size);
> +		struct dentry *dentry, bool *file_modified, u64 *size);
>   #endif   /* NFSD4_STATE_H */
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 0283cf366c2a..3fe289c74869 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -208,6 +208,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
>   #define ATTR_OPEN	(1 << 15) /* Truncating from open(O_TRUNC) */
>   #define ATTR_TIMES_SET	(1 << 16)
>   #define ATTR_TOUCH	(1 << 17)
> +#define ATTR_DELEG	(1 << 18) /* Delegated attrs (don't break) */
>   
>   /*
>    * Whiteout is represented by a char device.  The following constants define the
>
> ---
> base-commit: a204501e1743d695ca2930ed25a2be9f8ced96d3
> change-id: 20240823-nfsd-fixes-61f0c785d125
>
> Best regards,

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