text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Device operations for the pnfs nfs4 file layout driver.
   *
   * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
   *
   * Tao Peng <bergwolf@primarydata.com>
   */
  
  #include <linux/nfs_fs.h>
  #include <linux/vmalloc.h>
  #include <linux/module.h>
  #include <linux/sunrpc/addr.h>
  
  #include "../internal.h"
  #include "../nfs4session.h"
  #include "flexfilelayout.h"
  
  #define NFSDBG_FACILITY		NFSDBG_PNFS_LD
  
  static unsigned int dataserver_timeo = NFS_DEF_TCP_RETRANS;
  static unsigned int dataserver_retrans;
  
  static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);
  
  void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
  {
  	if (!IS_ERR_OR_NULL(mirror_ds))
  		nfs4_put_deviceid_node(&mirror_ds->id_node);
  }
  
  void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
  {
  	nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
  	nfs4_pnfs_ds_put(mirror_ds->ds);
  	kfree(mirror_ds->ds_versions);
  	kfree_rcu(mirror_ds, id_node.rcu);
  }
  
  /* Decode opaque device data and construct new_ds using it */
  struct nfs4_ff_layout_ds *
  nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
  			    gfp_t gfp_flags)
  {
  	struct xdr_stream stream;
  	struct xdr_buf buf;
  	struct page *scratch;
  	struct list_head dsaddrs;
  	struct nfs4_pnfs_ds_addr *da;
  	struct nfs4_ff_layout_ds *new_ds = NULL;
  	struct nfs4_ff_ds_version *ds_versions = NULL;
  	u32 mp_count;
  	u32 version_count;
  	__be32 *p;
  	int i, ret = -ENOMEM;
  
  	/* set up xdr stream */
  	scratch = alloc_page(gfp_flags);
  	if (!scratch)
  		goto out_err;
  
  	new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
  	if (!new_ds)
  		goto out_scratch;
  
  	nfs4_init_deviceid_node(&new_ds->id_node,
  				server,
  				&pdev->dev_id);
  	INIT_LIST_HEAD(&dsaddrs);
  
  	xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
  	xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
  
  	/* multipath count */
  	p = xdr_inline_decode(&stream, 4);
  	if (unlikely(!p))
  		goto out_err_drain_dsaddrs;
  	mp_count = be32_to_cpup(p);
  	dprintk("%s: multipath ds count %d\n", __func__, mp_count);
  
  	for (i = 0; i < mp_count; i++) {
  		/* multipath ds */
  		da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
  					    &stream, gfp_flags);
  		if (da)
  			list_add_tail(&da->da_node, &dsaddrs);
  	}
  	if (list_empty(&dsaddrs)) {
  		dprintk("%s: no suitable DS addresses found\n",
  			__func__);
  		ret = -ENOMEDIUM;
  		goto out_err_drain_dsaddrs;
  	}
  
  	/* version count */
  	p = xdr_inline_decode(&stream, 4);
  	if (unlikely(!p))
  		goto out_err_drain_dsaddrs;
  	version_count = be32_to_cpup(p);
  	dprintk("%s: version count %d\n", __func__, version_count);
  
  	ds_versions = kcalloc(version_count,
  			      sizeof(struct nfs4_ff_ds_version),
  			      gfp_flags);
  	if (!ds_versions)
  		goto out_scratch;
  
  	for (i = 0; i < version_count; i++) {
  		/* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
  		 * tightly_coupled(4) */
  		p = xdr_inline_decode(&stream, 20);
  		if (unlikely(!p))
  			goto out_err_drain_dsaddrs;
  		ds_versions[i].version = be32_to_cpup(p++);
  		ds_versions[i].minor_version = be32_to_cpup(p++);
  		ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
  		ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
  		ds_versions[i].tightly_coupled = be32_to_cpup(p);
  
  		if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
  			ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
  		if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
  			ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;
  
  		/*
  		 * check for valid major/minor combination.
  		 * currently we support dataserver which talk:
  		 *   v3, v4.0, v4.1, v4.2
  		 */
  		if (!((ds_versions[i].version == 3 && ds_versions[i].minor_version == 0) ||
  			(ds_versions[i].version == 4 && ds_versions[i].minor_version < 3))) {
  			dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
  				i, ds_versions[i].version,
  				ds_versions[i].minor_version);
  			ret = -EPROTONOSUPPORT;
  			goto out_err_drain_dsaddrs;
  		}
  
  		dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
  			__func__, i, ds_versions[i].version,
  			ds_versions[i].minor_version,
  			ds_versions[i].rsize,
  			ds_versions[i].wsize,
  			ds_versions[i].tightly_coupled);
  	}
  
  	new_ds->ds_versions = ds_versions;
  	new_ds->ds_versions_cnt = version_count;
  
  	new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
  	if (!new_ds->ds)
  		goto out_err_drain_dsaddrs;
  
  	/* If DS was already in cache, free ds addrs */
  	while (!list_empty(&dsaddrs)) {
  		da = list_first_entry(&dsaddrs,
  				      struct nfs4_pnfs_ds_addr,
  				      da_node);
  		list_del_init(&da->da_node);
  		kfree(da->da_remotestr);
  		kfree(da);
  	}
  
  	__free_page(scratch);
  	return new_ds;
  
  out_err_drain_dsaddrs:
  	while (!list_empty(&dsaddrs)) {
  		da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
  				      da_node);
  		list_del_init(&da->da_node);
  		kfree(da->da_remotestr);
  		kfree(da);
  	}
  
  	kfree(ds_versions);
  out_scratch:
  	__free_page(scratch);
  out_err:
  	kfree(new_ds);
  
  	dprintk("%s ERROR: returning %d\n", __func__, ret);
  	return NULL;
  }
  
  static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
  			    u64 offset, u64 length)
  {
  	u64 end;
  
  	end = max_t(u64, pnfs_end_offset(err->offset, err->length),
  		    pnfs_end_offset(offset, length));
  	err->offset = min_t(u64, err->offset, offset);
  	err->length = end - err->offset;
  }
  
  static int
  ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1,
  		const struct nfs4_ff_layout_ds_err *e2)
  {
  	int ret;
  
  	if (e1->opnum != e2->opnum)
  		return e1->opnum < e2->opnum ? -1 : 1;
  	if (e1->status != e2->status)
  		return e1->status < e2->status ? -1 : 1;
  	ret = memcmp(e1->stateid.data, e2->stateid.data,
  			sizeof(e1->stateid.data));
  	if (ret != 0)
  		return ret;
  	ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid));
  	if (ret != 0)
  		return ret;
  	if (pnfs_end_offset(e1->offset, e1->length) < e2->offset)
  		return -1;
  	if (e1->offset > pnfs_end_offset(e2->offset, e2->length))
  		return 1;
  	/* If ranges overlap or are contiguous, they are the same */
  	return 0;
  }
  
  static void
  ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
  			      struct nfs4_ff_layout_ds_err *dserr)
  {
  	struct nfs4_ff_layout_ds_err *err, *tmp;
  	struct list_head *head = &flo->error_list;
  	int match;
  
  	/* Do insertion sort w/ merges */
  	list_for_each_entry_safe(err, tmp, &flo->error_list, list) {
  		match = ff_ds_error_match(err, dserr);
  		if (match < 0)
  			continue;
  		if (match > 0) {
  			/* Add entry "dserr" _before_ entry "err" */
  			head = &err->list;
  			break;
  		}
  		/* Entries match, so merge "err" into "dserr" */
  		extend_ds_error(dserr, err->offset, err->length);
  		list_replace(&err->list, &dserr->list);
  		kfree(err);
  		return;
  	}
  
  	list_add_tail(&dserr->list, head);
  }
  
  int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
  			     struct nfs4_ff_layout_mirror *mirror, u64 offset,
  			     u64 length, int status, enum nfs_opnum4 opnum,
  			     gfp_t gfp_flags)
  {
  	struct nfs4_ff_layout_ds_err *dserr;
  
  	if (status == 0)
  		return 0;
  
  	if (mirror->mirror_ds == NULL)
  		return -EINVAL;
  
  	dserr = kmalloc(sizeof(*dserr), gfp_flags);
  	if (!dserr)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&dserr->list);
  	dserr->offset = offset;
  	dserr->length = length;
  	dserr->status = status;
  	dserr->opnum = opnum;
  	nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
  	memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
  	       NFS4_DEVICEID4_SIZE);
  
  	spin_lock(&flo->generic_hdr.plh_inode->i_lock);
  	ff_layout_add_ds_error_locked(flo, dserr);
  	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
  	return 0;
  }
  
  static const struct cred *
  ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode)
  {
  	const struct cred *cred, __rcu **pcred;
  
  	if (iomode == IOMODE_READ)
  		pcred = &mirror->ro_cred;
  	else
  		pcred = &mirror->rw_cred;
  
  	rcu_read_lock();
  	do {
  		cred = rcu_dereference(*pcred);
  		if (!cred)
  			break;
  
  		cred = get_cred_rcu(cred);
  	} while(!cred);
  	rcu_read_unlock();
  	return cred;
  }
  
  struct nfs_fh *
  nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror)
  {
  	/* FIXME: For now assume there is only 1 version available for the DS */
  	return &mirror->fh_versions[0];
  }
  
  void
  nfs4_ff_layout_select_ds_stateid(const struct nfs4_ff_layout_mirror *mirror,
  		nfs4_stateid *stateid)
  {
  	if (nfs4_ff_layout_ds_version(mirror) == 4)
  		nfs4_stateid_copy(stateid, &mirror->stateid);
  }
  
  static bool
  ff_layout_init_mirror_ds(struct pnfs_layout_hdr *lo,
  			 struct nfs4_ff_layout_mirror *mirror)
  {
  	if (mirror == NULL)
  		goto outerr;
  	if (mirror->mirror_ds == NULL) {
  		struct nfs4_deviceid_node *node;
  		struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV);
  
  		node = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode),
  				&mirror->devid, lo->plh_lc_cred,
  				GFP_KERNEL);
  		if (node)
  			mirror_ds = FF_LAYOUT_MIRROR_DS(node);
  
  		/* check for race with another call to this function */
  		if (cmpxchg(&mirror->mirror_ds, NULL, mirror_ds) &&
  		    mirror_ds != ERR_PTR(-ENODEV))
  			nfs4_put_deviceid_node(node);
  	}
  
  	if (IS_ERR(mirror->mirror_ds))
  		goto outerr;
  
  	return true;
  outerr:
  	return false;
  }
  
  /**
   * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call
   * @lseg: the layout segment we're operating on
   * @mirror: layout mirror describing the DS to use
   * @fail_return: return layout on connect failure?
   *
   * Try to prepare a DS connection to accept an RPC call. This involves
   * selecting a mirror to use and connecting the client to it if it's not
   * already connected.
   *
   * Since we only need a single functioning mirror to satisfy a read, we don't
   * want to return the layout if there is one. For writes though, any down
   * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish
   * between the two cases.
   *
   * Returns a pointer to a connected DS object on success or NULL on failure.
   */
  struct nfs4_pnfs_ds *
  nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
  			  struct nfs4_ff_layout_mirror *mirror,
  			  bool fail_return)
  {
  	struct nfs4_pnfs_ds *ds = NULL;
  	struct inode *ino = lseg->pls_layout->plh_inode;
  	struct nfs_server *s = NFS_SERVER(ino);
  	unsigned int max_payload;
  	int status;
  
  	if (!ff_layout_init_mirror_ds(lseg->pls_layout, mirror))
  		goto noconnect;
  
  	ds = mirror->mirror_ds->ds;
  	/* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
  	smp_rmb();
  	if (ds->ds_clp)
  		goto out;
  
  	/* FIXME: For now we assume the server sent only one version of NFS
  	 * to use for the DS.
  	 */
  	status = nfs4_pnfs_ds_connect(s, ds, &mirror->mirror_ds->id_node,
  			     dataserver_timeo, dataserver_retrans,
  			     mirror->mirror_ds->ds_versions[0].version,
  			     mirror->mirror_ds->ds_versions[0].minor_version);
  
  	/* connect success, check rsize/wsize limit */
  	if (!status) {
  		max_payload =
  			nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
  				       NULL);
  		if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
  			mirror->mirror_ds->ds_versions[0].rsize = max_payload;
  		if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
  			mirror->mirror_ds->ds_versions[0].wsize = max_payload;
  		goto out;
  	}
  noconnect:
  	ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
  				 mirror, lseg->pls_range.offset,
  				 lseg->pls_range.length, NFS4ERR_NXIO,
  				 OP_ILLEGAL, GFP_NOIO);
  	ff_layout_send_layouterror(lseg);
  	if (fail_return || !ff_layout_has_available_ds(lseg))
  		pnfs_error_mark_layout_for_return(ino, lseg);
  	ds = NULL;
  out:
  	return ds;
  }
  
  const struct cred *
  ff_layout_get_ds_cred(struct nfs4_ff_layout_mirror *mirror,
  		      const struct pnfs_layout_range *range,
  		      const struct cred *mdscred)
  {
  	const struct cred *cred;
  
  	if (mirror && !mirror->mirror_ds->ds_versions[0].tightly_coupled) {
  		cred = ff_layout_get_mirror_cred(mirror, range->iomode);
  		if (!cred)
  			cred = get_cred(mdscred);
  	} else {
  		cred = get_cred(mdscred);
  	}
  	return cred;
  }
  
  /**
   * nfs4_ff_find_or_create_ds_client - Find or create a DS rpc client
   * @mirror: pointer to the mirror
   * @ds_clp: nfs_client for the DS
   * @inode: pointer to inode
   *
   * Find or create a DS rpc client with th MDS server rpc client auth flavor
   * in the nfs_client cl_ds_clients list.
   */
  struct rpc_clnt *
  nfs4_ff_find_or_create_ds_client(struct nfs4_ff_layout_mirror *mirror,
  				 struct nfs_client *ds_clp, struct inode *inode)
  {
  	switch (mirror->mirror_ds->ds_versions[0].version) {
  	case 3:
  		/* For NFSv3 DS, flavor is set when creating DS connections */
  		return ds_clp->cl_rpcclient;
  	case 4:
  		return nfs4_find_or_create_ds_client(ds_clp, inode);
  	default:
  		BUG();
  	}
  }
  
  void ff_layout_free_ds_ioerr(struct list_head *head)
  {
  	struct nfs4_ff_layout_ds_err *err;
  
  	while (!list_empty(head)) {
  		err = list_first_entry(head,
  				struct nfs4_ff_layout_ds_err,
  				list);
  		list_del(&err->list);
  		kfree(err);
  	}
  }
  
  /* called with inode i_lock held */
  int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head)
  {
  	struct nfs4_ff_layout_ds_err *err;
  	__be32 *p;
  
  	list_for_each_entry(err, head, list) {
  		/* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
  		 * + array length + deviceid(NFS4_DEVICEID4_SIZE)
  		 * + status(4) + opnum(4)
  		 */
  		p = xdr_reserve_space(xdr,
  				28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
  		if (unlikely(!p))
  			return -ENOBUFS;
  		p = xdr_encode_hyper(p, err->offset);
  		p = xdr_encode_hyper(p, err->length);
  		p = xdr_encode_opaque_fixed(p, &err->stateid,
  					    NFS4_STATEID_SIZE);
  		/* Encode 1 error */
  		*p++ = cpu_to_be32(1);
  		p = xdr_encode_opaque_fixed(p, &err->deviceid,
  					    NFS4_DEVICEID4_SIZE);
  		*p++ = cpu_to_be32(err->status);
  		*p++ = cpu_to_be32(err->opnum);
  		dprintk("%s: offset %llu length %llu status %d op %d\n",
  			__func__, err->offset, err->length, err->status,
  			err->opnum);
  	}
  
  	return 0;
  }
  
  static
  unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
  				      const struct pnfs_layout_range *range,
  				      struct list_head *head,
  				      unsigned int maxnum)
  {
  	struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo);
  	struct inode *inode = lo->plh_inode;
  	struct nfs4_ff_layout_ds_err *err, *n;
  	unsigned int ret = 0;
  
  	spin_lock(&inode->i_lock);
  	list_for_each_entry_safe(err, n, &flo->error_list, list) {
  		if (!pnfs_is_range_intersecting(err->offset,
  				pnfs_end_offset(err->offset, err->length),
  				range->offset,
  				pnfs_end_offset(range->offset, range->length)))
  			continue;
  		if (!maxnum)
  			break;
  		list_move(&err->list, head);
  		maxnum--;
  		ret++;
  	}
  	spin_unlock(&inode->i_lock);
  	return ret;
  }
  
  unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
  				      const struct pnfs_layout_range *range,
  				      struct list_head *head,
  				      unsigned int maxnum)
  {
  	unsigned int ret;
  
  	ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum);
  	/* If we're over the max, discard all remaining entries */
  	if (ret == maxnum) {
  		LIST_HEAD(discard);
  		do_layout_fetch_ds_ioerr(lo, range, &discard, -1);
  		ff_layout_free_ds_ioerr(&discard);
  	}
  	return ret;
  }
  
  static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg)
  {
  	struct nfs4_ff_layout_mirror *mirror;
  	struct nfs4_deviceid_node *devid;
  	u32 idx;
  
  	for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
  		mirror = FF_LAYOUT_COMP(lseg, idx);
  		if (mirror) {
  			if (!mirror->mirror_ds)
  				return true;
  			if (IS_ERR(mirror->mirror_ds))
  				continue;
  			devid = &mirror->mirror_ds->id_node;
  			if (!nfs4_test_deviceid_unavailable(devid))
  				return true;
  		}
  	}
  
  	return false;
  }
  
  static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
  {
  	struct nfs4_ff_layout_mirror *mirror;
  	struct nfs4_deviceid_node *devid;
  	u32 idx;
  
  	for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
  		mirror = FF_LAYOUT_COMP(lseg, idx);
  		if (!mirror || IS_ERR(mirror->mirror_ds))
  			return false;
  		if (!mirror->mirror_ds)
  			continue;
  		devid = &mirror->mirror_ds->id_node;
  		if (nfs4_test_deviceid_unavailable(devid))
  			return false;
  	}
  
  	return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
  }
  
  static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
  {
  	if (lseg->pls_range.iomode == IOMODE_READ)
  		return  ff_read_layout_has_available_ds(lseg);
  	/* Note: RW layout needs all mirrors available */
  	return ff_rw_layout_has_available_ds(lseg);
  }
  
  bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg)
  {
  	return ff_layout_no_fallback_to_mds(lseg) ||
  	       ff_layout_has_available_ds(lseg);
  }
  
  bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg)
  {
  	return lseg->pls_range.iomode == IOMODE_RW &&
  	       ff_layout_no_read_on_rw(lseg);
  }
  
  module_param(dataserver_retrans, uint, 0644);
  MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
  			"retries a request before it attempts further "
  			" recovery  action.");
  module_param(dataserver_timeo, uint, 0644);
  MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
  			"NFSv4.1  client  waits for a response from a "
  			" data server before it retries an NFS request.");
  