nfsd: add support for delegated timestamps

Add support for the delegated timestamps on write delegations. This
allows the server to proxy timestamps from the delegation holder to
other clients that are doing GETATTRs vs. the same inode.

When OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS bit is set in the OPEN
call, set the dl_type to the *_ATTRS_DELEG flavor of delegation.

Add timespec64 fields to nfs4_cb_fattr and decode the timestamps into
those. Vet those timestamps according to the delstid spec and update
the inode attrs if necessary.

Signed-off-by: Jeff Layton <[e-mail]>
Signed-off-by: Chuck Lever <[e-mail]>

fs/nfsd/nfs4callback.c

···
 #include "trace.h"
 #include "xdr4cb.h"
 #include "xdr4.h"
+#include "nfs4xdr_gen.h"
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
···
 {
 	fattr->ncf_cb_change = 0;
 	fattr->ncf_cb_fsize = 0;
+	fattr->ncf_cb_atime.tv_sec = 0;
+	fattr->ncf_cb_atime.tv_nsec = 0;
+	fattr->ncf_cb_mtime.tv_sec = 0;
+	fattr->ncf_cb_mtime.tv_nsec = 0;
+
 	if (bitmap[0] & FATTR4_WORD0_CHANGE)
 		if (xdr_stream_decode_u64(xdr, &fattr->ncf_cb_change) < 0)
 			return -NFSERR_BAD_XDR;
 	if (bitmap[0] & FATTR4_WORD0_SIZE)
 		if (xdr_stream_decode_u64(xdr, &fattr->ncf_cb_fsize) < 0)
 			return -NFSERR_BAD_XDR;
+	if (bitmap[2] & FATTR4_WORD2_TIME_DELEG_ACCESS) {
+		fattr4_time_deleg_access access;
+
+		if (!xdrgen_decode_fattr4_time_deleg_access(xdr, &access))
+			return -NFSERR_BAD_XDR;
+		fattr->ncf_cb_atime.tv_sec = access.seconds;
+		fattr->ncf_cb_atime.tv_nsec = access.nseconds;
+
+	}
+	if (bitmap[2] & FATTR4_WORD2_TIME_DELEG_MODIFY) {
+		fattr4_time_deleg_modify modify;
+
+		if (!xdrgen_decode_fattr4_time_deleg_modify(xdr, &modify))
+			return -NFSERR_BAD_XDR;
+		fattr->ncf_cb_mtime.tv_sec = modify.seconds;
+		fattr->ncf_cb_mtime.tv_nsec = modify.nseconds;
+
+	}
 	return 0;
 }
 
···
 	struct nfs4_delegation *dp = container_of(fattr, struct nfs4_delegation, dl_cb_fattr);
 	struct knfsd_fh *fh = &dp->dl_stid.sc_file->fi_fhandle;
 	struct nfs4_cb_fattr *ncf = &dp->dl_cb_fattr;
-	u32 bmap[1];
+	u32 bmap_size = 1;
+	u32 bmap[3];
 
 	bmap[0] = FATTR4_WORD0_SIZE;
 	if (!ncf->ncf_file_modified)
 		bmap[0] |= FATTR4_WORD0_CHANGE;
 
+	if (deleg_attrs_deleg(dp->dl_type)) {
+		bmap[1] = 0;
+		bmap[2] = FATTR4_WORD2_TIME_DELEG_ACCESS | FATTR4_WORD2_TIME_DELEG_MODIFY;
+		bmap_size = 3;
+	}
 	encode_nfs_cb_opnum4(xdr, OP_CB_GETATTR);
 	encode_nfs_fh4(xdr, fh);
-	encode_bitmap4(xdr, bmap, ARRAY_SIZE(bmap));
+	encode_bitmap4(xdr, bmap, bmap_size);
 	hdr->nops++;
 }
 
···
 	struct nfs4_cb_compound_hdr hdr;
 	int status;
 	u32 bitmap[3] = {0};
-	u32 attrlen;
+	u32 attrlen, maxlen;
 	struct nfs4_cb_fattr *ncf =
 		container_of(cb, struct nfs4_cb_fattr, ncf_getattr);
 
···
 		return -NFSERR_BAD_XDR;
 	if (xdr_stream_decode_u32(xdr, &attrlen) < 0)
 		return -NFSERR_BAD_XDR;
-	if (attrlen > (sizeof(ncf->ncf_cb_change) + sizeof(ncf->ncf_cb_fsize)))
+	maxlen = sizeof(ncf->ncf_cb_change) + sizeof(ncf->ncf_cb_fsize);
+	if (bitmap[2] != 0)
+		maxlen += (sizeof(ncf->ncf_cb_mtime.tv_sec) +
+			   sizeof(ncf->ncf_cb_mtime.tv_nsec)) * 2;
+	if (attrlen > maxlen)
 		return -NFSERR_BAD_XDR;
 	status = decode_cb_fattr4(xdr, bitmap, ncf);
 	return status;

fs/nfsd/nfs4state.c

···
 nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
 		    struct svc_fh *parent)
 {
-	int status = 0;
+	bool deleg_ts = open->op_deleg_want & OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS;
 	struct nfs4_client *clp = stp->st_stid.sc_client;
 	struct nfs4_file *fp = stp->st_stid.sc_file;
 	struct nfs4_clnt_odstate *odstate = stp->st_clnt_odstate;
 	struct nfs4_delegation *dp;
 	struct nfsd_file *nf = NULL;
 	struct file_lease *fl;
+	int status = 0;
 	u32 dl_type;
 
 	/*
···
 	 */
 	if ((open->op_share_access & NFS4_SHARE_ACCESS_BOTH) == NFS4_SHARE_ACCESS_BOTH) {
 		nf = find_rw_file(fp);
-		dl_type = OPEN_DELEGATE_WRITE;
+		dl_type = deleg_ts ? OPEN_DELEGATE_WRITE_ATTRS_DELEG : OPEN_DELEGATE_WRITE;
 	}
 
 	/*
···
 	 */
 	if (!nf && (open->op_share_access & NFS4_SHARE_ACCESS_READ)) {
 		nf = find_readable_file(fp);
-		dl_type = OPEN_DELEGATE_READ;
+		dl_type = deleg_ts ? OPEN_DELEGATE_READ_ATTRS_DELEG : OPEN_DELEGATE_READ;
 	}
 
 	if (!nf)
···
 nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
 		     struct svc_fh *currentfh)
 {
-	struct nfs4_delegation *dp;
+	bool deleg_ts = open->op_deleg_want & OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS;
 	struct nfs4_openowner *oo = openowner(stp->st_stateowner);
 	struct nfs4_client *clp = stp->st_stid.sc_client;
 	struct svc_fh *parent = NULL;
-	int cb_up;
-	int status = 0;
+	struct nfs4_delegation *dp;
 	struct kstat stat;
+	int status = 0;
+	int cb_up;
 
 	cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
 	open->op_recall = false;
···
 			destroy_delegation(dp);
 			goto out_no_deleg;
 		}
-		open->op_delegate_type = OPEN_DELEGATE_WRITE;
+		open->op_delegate_type = deleg_ts ? OPEN_DELEGATE_WRITE_ATTRS_DELEG :
+						    OPEN_DELEGATE_WRITE;
 		dp->dl_cb_fattr.ncf_cur_fsize = stat.size;
 		dp->dl_cb_fattr.ncf_initial_cinfo = nfsd4_change_attribute(&stat);
 		trace_nfsd_deleg_write(&dp->dl_stid.sc_stateid);
 	} else {
-		open->op_delegate_type = OPEN_DELEGATE_READ;
+		open->op_delegate_type = deleg_ts ? OPEN_DELEGATE_READ_ATTRS_DELEG :
+						    OPEN_DELEGATE_READ;
 		trace_nfsd_deleg_read(&dp->dl_stid.sc_stateid);
 	}
 	nfs4_put_stid(&dp->dl_stid);
···
 }
 
 /**
+ * set_cb_time - vet and set the timespec for a cb_getattr update
+ * @cb: timestamp from the CB_GETATTR response
+ * @orig: original timestamp in the inode
+ * @now: current time
+ *
+ * Given a timestamp in a CB_GETATTR response, check it against the
+ * current timestamp in the inode and the current time. Returns true
+ * if the inode's timestamp needs to be updated, and false otherwise.
+ * @cb may also be changed if the timestamp needs to be clamped.
+ */
+static bool set_cb_time(struct timespec64 *cb, const struct timespec64 *orig,
+			const struct timespec64 *now)
+{
+
+	/*
+	 * "When the time presented is before the original time, then the
+	 *  update is ignored." Also no need to update if there is no change.
+	 */
+	if (timespec64_compare(cb, orig) <= 0)
+		return false;
+
+	/*
+	 * "When the time presented is in the future, the server can either
+	 *  clamp the new time to the current time, or it may
+	 *  return NFS4ERR_DELAY to the client, allowing it to retry."
+	 */
+	if (timespec64_compare(cb, now) > 0) {
+		/* clamp it */
+		*cb = *now;
+	}
+
+	return true;
+}
+
+static int cb_getattr_update_times(struct dentry *dentry, struct nfs4_delegation *dp)
+{
+	struct inode *inode = d_inode(dentry);
+	struct timespec64 now = current_time(inode);
+	struct nfs4_cb_fattr *ncf = &dp->dl_cb_fattr;
+	struct iattr attrs = { };
+	int ret;
+
+	if (deleg_attrs_deleg(dp->dl_type)) {
+		struct timespec64 atime = inode_get_atime(inode);
+		struct timespec64 mtime = inode_get_mtime(inode);
+
+		attrs.ia_atime = ncf->ncf_cb_atime;
+		attrs.ia_mtime = ncf->ncf_cb_mtime;
+
+		if (set_cb_time(&attrs.ia_atime, &atime, &now))
+			attrs.ia_valid |= ATTR_ATIME | ATTR_ATIME_SET;
+
+		if (set_cb_time(&attrs.ia_mtime, &mtime, &now)) {
+			attrs.ia_valid |= ATTR_CTIME | ATTR_MTIME | ATTR_MTIME_SET;
+			attrs.ia_ctime = attrs.ia_mtime;
+		}
+	} else {
+		attrs.ia_valid |= ATTR_MTIME | ATTR_CTIME;
+		attrs.ia_mtime = attrs.ia_ctime = now;
+	}
+
+	if (!attrs.ia_valid)
+		return 0;
+
+	attrs.ia_valid |= ATTR_DELEG;
+	inode_lock(inode);
+	ret = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
+	inode_unlock(inode);
+	return ret;
+}
+
+/**
  * nfsd4_deleg_getattr_conflict - Recall if GETATTR causes conflict
  * @rqstp: RPC transaction context
  * @dentry: dentry of inode to be checked for a conflict
···
 	struct file_lock_context *ctx;
 	struct nfs4_delegation *dp = NULL;
 	struct file_lease *fl;
-	struct iattr attrs;
 	struct nfs4_cb_fattr *ncf;
 	struct inode *inode = d_inode(dentry);
 
···
 		 * 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 | ATTR_DELEG;
-		inode_lock(inode);
-		err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
-		inode_unlock(inode);
+		err = cb_getattr_update_times(dentry, dp);
 		if (err) {
 			status = nfserrno(err);
 			goto out_status;

fs/nfsd/nfs4xdr.c

···
 
 #define NFSD_OA_SHARE_ACCESS_WANT	(BIT(OPEN_ARGS_SHARE_ACCESS_WANT_ANY_DELEG)		| \
 					 BIT(OPEN_ARGS_SHARE_ACCESS_WANT_NO_DELEG)		| \
-					 BIT(OPEN_ARGS_SHARE_ACCESS_WANT_CANCEL))
+					 BIT(OPEN_ARGS_SHARE_ACCESS_WANT_CANCEL)		| \
+					 BIT(OPEN_ARGS_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS))
 
 #define NFSD_OA_OPEN_CLAIM	(BIT(OPEN_ARGS_OPEN_CLAIM_NULL)		| \
 				 BIT(OPEN_ARGS_OPEN_CLAIM_PREVIOUS)	| \
···
 		if (status)
 			goto out;
 	}
-	if (attrmask[0] & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
+	if ((attrmask[0] & (FATTR4_WORD0_CHANGE |
+			    FATTR4_WORD0_SIZE)) ||
+	    (attrmask[1] & (FATTR4_WORD1_TIME_ACCESS |
+			    FATTR4_WORD1_TIME_MODIFY |
+			    FATTR4_WORD1_TIME_METADATA))) {
 		status = nfsd4_deleg_getattr_conflict(rqstp, dentry, &dp);
 		if (status)
 			goto out;
···
 		if (ncf->ncf_file_modified) {
 			++ncf->ncf_initial_cinfo;
 			args.stat.size = ncf->ncf_cur_fsize;
+			if (!timespec64_is_epoch(&ncf->ncf_cb_mtime))
+				args.stat.mtime = ncf->ncf_cb_mtime;
 		}
 		args.change_attr = ncf->ncf_initial_cinfo;
+
+		if (!timespec64_is_epoch(&ncf->ncf_cb_atime))
+			args.stat.atime = ncf->ncf_cb_atime;
+
 		nfs4_put_stid(&dp->dl_stid);
 	} else {
 		args.change_attr = nfsd4_change_attribute(&args.stat);

fs/nfsd/nfsd.h

···
 	FATTR4_WORD2_MODE_UMASK | \
 	NFSD4_2_SECURITY_ATTRS | \
 	FATTR4_WORD2_XATTR_SUPPORT | \
+	FATTR4_WORD2_TIME_DELEG_ACCESS | \
+	FATTR4_WORD2_TIME_DELEG_MODIFY | \
 	FATTR4_WORD2_OPEN_ARGUMENTS)
 
 extern const u32 nfsd_suppattrs[3][3];

fs/nfsd/state.h

···
 	/* from CB_GETATTR reply */
 	u64 ncf_cb_change;
 	u64 ncf_cb_fsize;
+	struct timespec64 ncf_cb_mtime;
+	struct timespec64 ncf_cb_atime;
 
 	unsigned long ncf_cb_flags;
 	bool ncf_file_modified;

fs/nfsd/xdr4cb.h

···
  * 1: CB_GETATTR opcode (32-bit)
  * N: file_handle
  * 1: number of entry in attribute array (32-bit)
- * 1: entry 0 in attribute array (32-bit)
+ * 3: entry 0-2 in attribute array (32-bit * 3)
  */
 #define NFS4_enc_cb_getattr_sz		(cb_compound_enc_hdr_sz +       \
 					cb_sequence_enc_sz +            \
-					1 + enc_nfs4_fh_sz + 1 + 1)
+					1 + enc_nfs4_fh_sz + 1 + 3)
 /*
  * 4: fattr_bitmap_maxsz
  * 1: attribute array len
  * 2: change attr (64-bit)
  * 2: size (64-bit)
+ * 2: atime.seconds (64-bit)
+ * 1: atime.nanoseconds (32-bit)
+ * 2: mtime.seconds (64-bit)
+ * 1: mtime.nanoseconds (32-bit)
  */
 #define NFS4_dec_cb_getattr_sz		(cb_compound_dec_hdr_sz  +      \
-			cb_sequence_dec_sz + 4 + 1 + 2 + 2 + op_dec_sz)
+			cb_sequence_dec_sz + 4 + 1 + 2 + 2 + 2 + 1 + 2 + 1 + op_dec_sz)

include/linux/time64.h

···
 	return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec);
 }
 
+static inline bool timespec64_is_epoch(const struct timespec64 *ts)
+{
+	return ts->tv_sec == 0 && ts->tv_nsec == 0;
+}
+
 /*
  * lhs < rhs:  return <0
  * lhs == rhs: return 0