[RFC PATCH v2 3/8] NFSD: filecache: add STATX_DIOALIGN and STATX_DIO_READ_ALIGN support

[Mike Snitzer <snitzer@kernel.org>]

Use STATX_DIOALIGN and STATX_DIO_READ_ALIGN to get and store DIO
alignment attributes from underlying filesystem in associated
nfsd_file.  This is done when the nfsd_file is first opened for
a regular file.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
 fs/nfsd/filecache.c | 32 ++++++++++++++++++++++++++++++++
 fs/nfsd/filecache.h |  4 ++++
 fs/nfsd/nfsfh.c     |  4 ++++
 3 files changed, 40 insertions(+)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 905034fd8c34..e8a9336b42f5 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -231,6 +231,9 @@ nfsd_file_alloc(struct net *net, struct inode *inode, unsigned char need,
 	refcount_set(&nf->nf_ref, 1);
 	nf->nf_may = need;
 	nf->nf_mark = NULL;
+	nf->nf_dio_mem_align = 0;
+	nf->nf_dio_offset_align = 0;
+	nf->nf_dio_read_offset_align = 0;
 	return nf;
 }
 
@@ -1064,6 +1067,33 @@ nfsd_file_is_cached(struct inode *inode)
 	return ret;
 }
 
+static __be32
+nfsd_file_getattr(const struct svc_fh *fhp, struct nfsd_file *nf)
+{
+	struct inode *inode = file_inode(nf->nf_file);
+	struct kstat stat;
+	__be32 status;
+
+	/* Currently only need to get DIO alignment info for regular files */
+	if (!S_ISREG(inode->i_mode))
+		return nfs_ok;
+
+	status = fh_getattr(fhp, &stat);
+	if (status != nfs_ok)
+		return status;
+
+	if (stat.result_mask & STATX_DIOALIGN) {
+		nf->nf_dio_mem_align = stat.dio_mem_align;
+		nf->nf_dio_offset_align = stat.dio_offset_align;
+	}
+	if (stat.result_mask & STATX_DIO_READ_ALIGN)
+		nf->nf_dio_read_offset_align = stat.dio_read_offset_align;
+	else
+		nf->nf_dio_read_offset_align = nf->nf_dio_offset_align;
+
+	return status;
+}
+
 static __be32
 nfsd_file_do_acquire(struct svc_rqst *rqstp, struct net *net,
 		     struct svc_cred *cred,
@@ -1182,6 +1212,8 @@ nfsd_file_do_acquire(struct svc_rqst *rqstp, struct net *net,
 			}
 			status = nfserrno(ret);
 			trace_nfsd_file_open(nf, status);
+			if (status == nfs_ok)
+				status = nfsd_file_getattr(fhp, nf);
 		}
 	} else
 		status = nfserr_jukebox;
diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h
index cd02f91aaef1..d41428ce8a11 100644
--- a/fs/nfsd/filecache.h
+++ b/fs/nfsd/filecache.h
@@ -54,6 +54,10 @@ struct nfsd_file {
 	struct list_head	nf_gc;
 	struct rcu_head		nf_rcu;
 	ktime_t			nf_birthtime;
+
+	u32			nf_dio_mem_align;
+	u32			nf_dio_offset_align;
+	u32			nf_dio_read_offset_align;
 };
 
 int nfsd_file_cache_init(void);
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index f4a3cc9e31e0..bdba2ba828a6 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -677,8 +677,12 @@ __be32 fh_getattr(const struct svc_fh *fhp, struct kstat *stat)
 		.mnt		= fhp->fh_export->ex_path.mnt,
 		.dentry		= fhp->fh_dentry,
 	};
+	struct inode *inode = d_inode(p.dentry);
 	u32 request_mask = STATX_BASIC_STATS;
 
+	if (S_ISREG(inode->i_mode))
+		request_mask |= (STATX_DIOALIGN | STATX_DIO_READ_ALIGN);
+
 	if (fhp->fh_maxsize == NFS4_FHSIZE)
 		request_mask |= (STATX_BTIME | STATX_CHANGE_COOKIE);
 
-- 
2.44.0