Re: [PATCH 11/12] nfsd: use (un)lock_inode instead of fh_(un)lock

From: Chuck Lever III
Date: Fri Jun 24 2022 - 10:49:20 EST

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> On Jun 13, 2022, at 7:18 PM, NeilBrown <neilb@xxxxxxx> wrote:
>
> Except for the xattr changes, these callers don't need to save pre/post
> attrs, so use a simple lock/unlock.
>
> For the xattr changes, make the saving of pre/post explicit rather than
> requiring a comment.
>
> Also many fh_unlock() are not needed.

This patch does three different (though related) things. I prefer to
instead see three patches:

- One that changes the xattr code, as described
- One that cleans up unneeded fh_unlock calls, with an explanation of
why that is safe to do
- One that replaces fh_lock() with inode_lock (or inode_lock_nested,
see below).

> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> fs/nfsd/nfs2acl.c | 6 +++---
> fs/nfsd/nfs3acl.c | 4 ++--
> fs/nfsd/nfs3proc.c | 4 ----
> fs/nfsd/nfs4acl.c | 7 +++----
> fs/nfsd/nfs4proc.c | 2 --
> fs/nfsd/nfs4state.c | 8 ++++----
> fs/nfsd/nfsfh.c | 1 -
> fs/nfsd/nfsfh.h | 8 --------
> fs/nfsd/vfs.c | 26 ++++++++++++--------------
> 9 files changed, 24 insertions(+), 42 deletions(-)
>
> diff --git a/fs/nfsd/nfs2acl.c b/fs/nfsd/nfs2acl.c
> index b5760801d377..9edd3c1a30fb 100644
> --- a/fs/nfsd/nfs2acl.c
> +++ b/fs/nfsd/nfs2acl.c
> @@ -111,7 +111,7 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
> if (error)
> goto out_errno;
>
> - fh_lock(fh);
> + inode_lock(inode);

fh_lock() uses inode_lock_nested(). If the above hunk is the
correct substitution, the patch description should explain why
that is correct. Otherwise, shall we use inode_lock_nested()
here too?

Likewise throughout.

> error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS,
> argp->acl_access);
> @@ -122,7 +122,7 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
> if (error)
> goto out_drop_lock;
>
> - fh_unlock(fh);
> + inode_unlock(inode);
>
> fh_drop_write(fh);
>
> @@ -136,7 +136,7 @@ static __be32 nfsacld_proc_setacl(struct svc_rqst *rqstp)
> return rpc_success;
>
> out_drop_lock:
> - fh_unlock(fh);
> + inode_unlock(inode);
> fh_drop_write(fh);
> out_errno:
> resp->status = nfserrno(error);
> diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
> index 35b2ebda14da..9446c6743664 100644
> --- a/fs/nfsd/nfs3acl.c
> +++ b/fs/nfsd/nfs3acl.c
> @@ -101,7 +101,7 @@ static __be32 nfsd3_proc_setacl(struct svc_rqst *rqstp)
> if (error)
> goto out_errno;
>
> - fh_lock(fh);
> + inode_lock(inode);
>
> error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS,
> argp->acl_access);
> @@ -111,7 +111,7 @@ static __be32 nfsd3_proc_setacl(struct svc_rqst *rqstp)
> argp->acl_default);
>
> out_drop_lock:
> - fh_unlock(fh);
> + inode_unlock(inode);
> fh_drop_write(fh);
> out_errno:
> resp->status = nfserrno(error);
> diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> index d85b110d58dd..7bb07c7e6ee8 100644
> --- a/fs/nfsd/nfs3proc.c
> +++ b/fs/nfsd/nfs3proc.c
> @@ -374,7 +374,6 @@ nfsd3_proc_mkdir(struct svc_rqst *rqstp)
> fh_init(&resp->fh, NFS3_FHSIZE);
> resp->status = nfsd_create(rqstp, &resp->dirfh, argp->name, argp->len,
> &argp->attrs, S_IFDIR, 0, &resp->fh);
> - fh_unlock(&resp->dirfh);
> return rpc_success;
> }
>
> @@ -449,7 +448,6 @@ nfsd3_proc_mknod(struct svc_rqst *rqstp)
> type = nfs3_ftypes[argp->ftype];
> resp->status = nfsd_create(rqstp, &resp->dirfh, argp->name, argp->len,
> &argp->attrs, type, rdev, &resp->fh);
> - fh_unlock(&resp->dirfh);
> out:
> return rpc_success;
> }
> @@ -472,7 +470,6 @@ nfsd3_proc_remove(struct svc_rqst *rqstp)
> fh_copy(&resp->fh, &argp->fh);
> resp->status = nfsd_unlink(rqstp, &resp->fh, -S_IFDIR,
> argp->name, argp->len);
> - fh_unlock(&resp->fh);
> return rpc_success;
> }
>
> @@ -493,7 +490,6 @@ nfsd3_proc_rmdir(struct svc_rqst *rqstp)
> fh_copy(&resp->fh, &argp->fh);
> resp->status = nfsd_unlink(rqstp, &resp->fh, S_IFDIR,
> argp->name, argp->len);
> - fh_unlock(&resp->fh);
> return rpc_success;
> }
>
> diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c
> index eaa3a0cf38f1..7bcc6dc0f762 100644
> --- a/fs/nfsd/nfs4acl.c
> +++ b/fs/nfsd/nfs4acl.c
> @@ -779,19 +779,18 @@ nfsd4_set_nfs4_acl(struct svc_rqst *rqstp, struct svc_fh *fhp,
> if (host_error < 0)
> goto out_nfserr;
>
> - fh_lock(fhp);
> + inode_lock(inode);
>
> host_error = set_posix_acl(&init_user_ns, inode, ACL_TYPE_ACCESS, pacl);
> if (host_error < 0)
> goto out_drop_lock;
>
> - if (S_ISDIR(inode->i_mode)) {
> + if (S_ISDIR(inode->i_mode))
> host_error = set_posix_acl(&init_user_ns, inode,
> ACL_TYPE_DEFAULT, dpacl);
> - }
>
> out_drop_lock:
> - fh_unlock(fhp);
> + inode_unlock(inode);
>
> posix_acl_release(pacl);
> posix_acl_release(dpacl);
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 79434e29b63f..d6defaf5a77a 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -860,7 +860,6 @@ nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> do_set_nfs4_acl(rqstp, &resfh, create->cr_acl,
> create->cr_bmval);
>
> - fh_unlock(&cstate->current_fh);
> set_change_info(&create->cr_cinfo, &cstate->current_fh);
> fh_dup2(&cstate->current_fh, &resfh);
> out:
> @@ -1040,7 +1039,6 @@ nfsd4_remove(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> status = nfsd_unlink(rqstp, &cstate->current_fh, 0,
> remove->rm_name, remove->rm_namelen);
> if (!status) {
> - fh_unlock(&cstate->current_fh);
> set_change_info(&remove->rm_cinfo, &cstate->current_fh);
> }
> return status;
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 9409a0dc1b76..cb664c61b546 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7321,21 +7321,21 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> static __be32 nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
> {
> struct nfsd_file *nf;
> + struct inode *inode = fhp->fh_dentry->d_inode;
> __be32 err;
>
> err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
> if (err)
> return err;
> - fh_lock(fhp); /* to block new leases till after test_lock: */
> - err = nfserrno(nfsd_open_break_lease(fhp->fh_dentry->d_inode,
> - NFSD_MAY_READ));
> + inode_lock(inode); /* to block new leases till after test_lock: */
> + err = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
> if (err)
> goto out;
> lock->fl_file = nf->nf_file;
> err = nfserrno(vfs_test_lock(nf->nf_file, lock));
> lock->fl_file = NULL;
> out:
> - fh_unlock(fhp);
> + inode_unlock(inode);
> nfsd_file_put(nf);
> return err;
> }
> diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
> index a50db688c60d..ae270e4f921f 100644
> --- a/fs/nfsd/nfsfh.c
> +++ b/fs/nfsd/nfsfh.c
> @@ -685,7 +685,6 @@ fh_put(struct svc_fh *fhp)
> struct dentry * dentry = fhp->fh_dentry;
> struct svc_export * exp = fhp->fh_export;
> if (dentry) {
> - fh_unlock(fhp);
> fhp->fh_dentry = NULL;
> dput(dentry);
> fh_clear_pre_post_attrs(fhp);
> diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
> index ecc57fd3fd67..c5061cdb1016 100644
> --- a/fs/nfsd/nfsfh.h
> +++ b/fs/nfsd/nfsfh.h
> @@ -323,14 +323,6 @@ static inline u64 nfsd4_change_attribute(struct kstat *stat,
> extern void fh_fill_pre_attrs(struct svc_fh *fhp, bool atomic);
> extern void fh_fill_post_attrs(struct svc_fh *fhp);
>
> -
> -/*
> - * Lock a file handle/inode
> - * NOTE: both fh_lock and fh_unlock are done "by hand" in
> - * vfs.c:nfsd_rename as it needs to grab 2 i_mutex's at once
> - * so, any changes here should be reflected there.
> - */
> -
> static inline void
> fh_lock_nested(struct svc_fh *fhp, unsigned int subclass)
> {
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 4c2e431100ba..f2f4868618bb 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -253,7 +253,6 @@ nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
> * returned. Otherwise the covered directory is returned.
> * NOTE: this mountpoint crossing is not supported properly by all
> * clients and is explicitly disallowed for NFSv3
> - * NeilBrown <neilb@xxxxxxxxxxxxxxx>
> */
> __be32
> nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
> @@ -434,7 +433,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
> return err;
> }
>
> - fh_lock(fhp);
> + inode_lock(inode);
> if (size_change) {
> /*
> * RFC5661, Section 18.30.4:
> @@ -470,7 +469,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
> host_err = notify_change(&init_user_ns, dentry, iap, NULL);
>
> out_unlock:
> - fh_unlock(fhp);
> + inode_unlock(inode);
> if (size_change)
> put_write_access(inode);
> out:
> @@ -2123,12 +2122,8 @@ nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
> }
>
> /*
> - * Removexattr and setxattr need to call fh_lock to both lock the inode
> - * and set the change attribute. Since the top-level vfs_removexattr
> - * and vfs_setxattr calls already do their own inode_lock calls, call
> - * the _locked variant. Pass in a NULL pointer for delegated_inode,
> - * and let the client deal with NFS4ERR_DELAY (same as with e.g.
> - * setattr and remove).
> + * Pass in a NULL pointer for delegated_inode, and let the client deal
> + * with NFS4ERR_DELAY (same as with e.g. setattr and remove).
> */
> __be32
> nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
> @@ -2144,12 +2139,14 @@ nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
> if (ret)
> return nfserrno(ret);
>
> - fh_lock(fhp);
> + inode_lock(fhp->fh_dentry->d_inode);
> + fh_fill_pre_attrs(fhp, true);
>
> ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
> name, NULL);
>
> - fh_unlock(fhp);
> + fh_fill_post_attrs(fhp);
> + inode_unlock(fhp->fh_dentry->d_inode);
> fh_drop_write(fhp);
>
> return nfsd_xattr_errno(ret);
> @@ -2169,12 +2166,13 @@ nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
> ret = fh_want_write(fhp);
> if (ret)
> return nfserrno(ret);
> - fh_lock(fhp);
> + inode_lock(fhp->fh_dentry->d_inode);
> + fh_fill_pre_attrs(fhp, true);
>
> ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
> len, flags, NULL);
> -
> - fh_unlock(fhp);
> + fh_fill_post_attrs(fhp);
> + inode_unlock(fhp->fh_dentry->d_inode);
> fh_drop_write(fhp);
>
> return nfsd_xattr_errno(ret);
>
>

--
Chuck Lever

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