Re: [RFC PATCH 19/35] libceph, ceph: Convert users of ceph_pagelist to ceph_databuf

[Viacheslav Dubeyko]

On Thu, 2025-03-13 at 23:33 +0000, David Howells wrote:
> Convert users of ceph_pagelist to use ceph_databuf instead.  ceph_pagelist
> is then unused and can be removed.
> 
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Viacheslav Dubeyko <slava@xxxxxxxxxxx>
> cc: Alex Markuze <amarkuze@xxxxxxxxxx>
> cc: Ilya Dryomov <idryomov@xxxxxxxxx>
> cc: ceph-devel@xxxxxxxxxxxxxxx
> cc: linux-fsdevel@xxxxxxxxxxxxxxx
> ---
>  fs/ceph/locks.c                 |  22 +++---
>  fs/ceph/mds_client.c            | 122 +++++++++++++++-----------------
>  fs/ceph/super.h                 |   6 +-
>  include/linux/ceph/osd_client.h |   2 +-
>  net/ceph/osd_client.c           |  61 ++++++++--------
>  5 files changed, 104 insertions(+), 109 deletions(-)
> 
> diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
> index ebf4ac0055dd..32c7b0f0d61f 100644
> --- a/fs/ceph/locks.c
> +++ b/fs/ceph/locks.c
> @@ -371,8 +371,8 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
>  }
>  
>  /*
> - * Fills in the passed counter variables, so you can prepare pagelist metadata
> - * before calling ceph_encode_locks.
> + * Fills in the passed counter variables, so you can prepare metadata before
> + * calling ceph_encode_locks.
>   */
>  void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
>  {
> @@ -483,38 +483,38 @@ int ceph_encode_locks_to_buffer(struct inode *inode,
>  }
>  
>  /*
> - * Copy the encoded flock and fcntl locks into the pagelist.
> + * Copy the encoded flock and fcntl locks into the data buffer.
>   * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
>   * sequential flock locks.
>   * Returns zero on success.
>   */
> -int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
> -			   struct ceph_pagelist *pagelist,
> +int ceph_locks_to_databuf(struct ceph_filelock *flocks,
> +			   struct ceph_databuf *dbuf,
>  			   int num_fcntl_locks, int num_flock_locks)
>  {
>  	int err = 0;
>  	__le32 nlocks;
>  
>  	nlocks = cpu_to_le32(num_fcntl_locks);
> -	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
> +	err = ceph_databuf_append(dbuf, &nlocks, sizeof(nlocks));
>  	if (err)
>  		goto out_fail;
>  
>  	if (num_fcntl_locks > 0) {
> -		err = ceph_pagelist_append(pagelist, flocks,
> -					   num_fcntl_locks * sizeof(*flocks));
> +		err = ceph_databuf_append(dbuf, flocks,
> +					  num_fcntl_locks * sizeof(*flocks));
>  		if (err)
>  			goto out_fail;
>  	}
>  
>  	nlocks = cpu_to_le32(num_flock_locks);
> -	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
> +	err = ceph_databuf_append(dbuf, &nlocks, sizeof(nlocks));
>  	if (err)
>  		goto out_fail;
>  
>  	if (num_flock_locks > 0) {
> -		err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
> -					   num_flock_locks * sizeof(*flocks));
> +		err = ceph_databuf_append(dbuf, &flocks[num_fcntl_locks],
> +					  num_flock_locks * sizeof(*flocks));
>  	}
>  out_fail:
>  	return err;
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 09661a34f287..f1c6d0ebf548 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -55,7 +55,7 @@
>  struct ceph_reconnect_state {
>  	struct ceph_mds_session *session;
>  	int nr_caps, nr_realms;
> -	struct ceph_pagelist *pagelist;
> +	struct ceph_databuf *dbuf;
>  	unsigned msg_version;
>  	bool allow_multi;
>  };
> @@ -4456,8 +4456,7 @@ static void replay_unsafe_requests(struct ceph_mds_client *mdsc,
>  static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
>  {
>  	struct ceph_msg *reply;
> -	struct ceph_pagelist *_pagelist;
> -	struct page *page;
> +	struct ceph_databuf *_dbuf;
>  	__le32 *addr;
>  	int err = -ENOMEM;
>  
> @@ -4467,9 +4466,9 @@ static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
>  	/* can't handle message that contains both caps and realm */
>  	BUG_ON(!recon_state->nr_caps == !recon_state->nr_realms);
>  
> -	/* pre-allocate new pagelist */
> -	_pagelist = ceph_pagelist_alloc(GFP_NOFS);
> -	if (!_pagelist)
> +	/* pre-allocate new databuf */
> +	_dbuf = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_NOFS);
> +	if (!_dbuf)
>  		return -ENOMEM;
>  
>  	reply = ceph_msg_new2(CEPH_MSG_CLIENT_RECONNECT, 0, 1, GFP_NOFS, false);
> @@ -4477,28 +4476,27 @@ static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
>  		goto fail_msg;
>  
>  	/* placeholder for nr_caps */
> -	err = ceph_pagelist_encode_32(_pagelist, 0);
> +	err = ceph_databuf_encode_32(_dbuf, 0);
>  	if (err < 0)
>  		goto fail;
>  
>  	if (recon_state->nr_caps) {
>  		/* currently encoding caps */
> -		err = ceph_pagelist_encode_32(recon_state->pagelist, 0);
> +		err = ceph_databuf_encode_32(recon_state->dbuf, 0);
>  		if (err)
>  			goto fail;
>  	} else {
>  		/* placeholder for nr_realms (currently encoding relams) */
> -		err = ceph_pagelist_encode_32(_pagelist, 0);
> +		err = ceph_databuf_encode_32(_dbuf, 0);
>  		if (err < 0)
>  			goto fail;
>  	}
>  
> -	err = ceph_pagelist_encode_8(recon_state->pagelist, 1);
> +	err = ceph_databuf_encode_8(recon_state->dbuf, 1);
>  	if (err)
>  		goto fail;
>  
> -	page = list_first_entry(&recon_state->pagelist->head, struct page, lru);
> -	addr = kmap_atomic(page);
> +	addr = kmap_ceph_databuf_page(recon_state->dbuf, 0);
>  	if (recon_state->nr_caps) {
>  		/* currently encoding caps */
>  		*addr = cpu_to_le32(recon_state->nr_caps);
> @@ -4506,18 +4504,18 @@ static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
>  		/* currently encoding relams */
>  		*(addr + 1) = cpu_to_le32(recon_state->nr_realms);
>  	}
> -	kunmap_atomic(addr);
> +	kunmap_local(addr);
>  
>  	reply->hdr.version = cpu_to_le16(5);
>  	reply->hdr.compat_version = cpu_to_le16(4);
>  
> -	reply->hdr.data_len = cpu_to_le32(recon_state->pagelist->length);
> -	ceph_msg_data_add_pagelist(reply, recon_state->pagelist);
> +	reply->hdr.data_len = cpu_to_le32(ceph_databuf_len(recon_state->dbuf));
> +	ceph_msg_data_add_databuf(reply, recon_state->dbuf);
>  
>  	ceph_con_send(&recon_state->session->s_con, reply);
> -	ceph_pagelist_release(recon_state->pagelist);
> +	ceph_databuf_release(recon_state->dbuf);
>  
> -	recon_state->pagelist = _pagelist;
> +	recon_state->dbuf = _dbuf;
>  	recon_state->nr_caps = 0;
>  	recon_state->nr_realms = 0;
>  	recon_state->msg_version = 5;
> @@ -4525,7 +4523,7 @@ static int send_reconnect_partial(struct ceph_reconnect_state *recon_state)
>  fail:
>  	ceph_msg_put(reply);
>  fail_msg:
> -	ceph_pagelist_release(_pagelist);
> +	ceph_databuf_release(_dbuf);
>  	return err;
>  }
>  
> @@ -4575,7 +4573,7 @@ static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
>  	} rec;
>  	struct ceph_inode_info *ci = ceph_inode(inode);
>  	struct ceph_reconnect_state *recon_state = arg;
> -	struct ceph_pagelist *pagelist = recon_state->pagelist;
> +	struct ceph_databuf *dbuf = recon_state->dbuf;
>  	struct dentry *dentry;
>  	struct ceph_cap *cap;
>  	char *path;
> @@ -4698,7 +4696,7 @@ static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
>  			struct_v = 2;
>  		}
>  		/*
> -		 * number of encoded locks is stable, so copy to pagelist
> +		 * number of encoded locks is stable, so copy to databuf
>  		 */
>  		struct_len = 2 * sizeof(u32) +
>  			    (num_fcntl_locks + num_flock_locks) *

I think we have too many mysterious equations in CephFS code. :)

> @@ -4712,41 +4710,42 @@ static int reconnect_caps_cb(struct inode *inode, int mds, void *arg)
>  
>  		total_len += struct_len;
>  
> -		if (pagelist->length + total_len > RECONNECT_MAX_SIZE) {
> +		if (ceph_databuf_len(dbuf) + total_len > RECONNECT_MAX_SIZE) {
>  			err = send_reconnect_partial(recon_state);
>  			if (err)
>  				goto out_freeflocks;
> -			pagelist = recon_state->pagelist;
> +			dbuf = recon_state->dbuf;
>  		}
>  
> -		err = ceph_pagelist_reserve(pagelist, total_len);
> +		err = ceph_databuf_reserve(dbuf, total_len, GFP_NOFS);
>  		if (err)
>  			goto out_freeflocks;
>  
> -		ceph_pagelist_encode_64(pagelist, ceph_ino(inode));
> +		ceph_databuf_encode_64(dbuf, ceph_ino(inode));
>  		if (recon_state->msg_version >= 3) {
> -			ceph_pagelist_encode_8(pagelist, struct_v);
> -			ceph_pagelist_encode_8(pagelist, 1);
> -			ceph_pagelist_encode_32(pagelist, struct_len);
> +			ceph_databuf_encode_8(dbuf, struct_v);
> +			ceph_databuf_encode_8(dbuf, 1);
> +			ceph_databuf_encode_32(dbuf, struct_len);
>  		}
> -		ceph_pagelist_encode_string(pagelist, path, pathlen);
> -		ceph_pagelist_append(pagelist, &rec, sizeof(rec.v2));
> -		ceph_locks_to_pagelist(flocks, pagelist,
> -				       num_fcntl_locks, num_flock_locks);
> +		ceph_databuf_encode_string(dbuf, path, pathlen);
> +		ceph_databuf_append(dbuf, &rec, sizeof(rec.v2));
> +		ceph_locks_to_databuf(flocks, dbuf,
> +				      num_fcntl_locks, num_flock_locks);
>  		if (struct_v >= 2)
> -			ceph_pagelist_encode_64(pagelist, snap_follows);
> +			ceph_databuf_encode_64(dbuf, snap_follows);
>  out_freeflocks:
>  		kfree(flocks);
>  	} else {
> -		err = ceph_pagelist_reserve(pagelist,
> -					    sizeof(u64) + sizeof(u32) +
> -					    pathlen + sizeof(rec.v1));
> +		err = ceph_databuf_reserve(dbuf,
> +					   sizeof(u64) + sizeof(u32) +
> +					   pathlen + sizeof(rec.v1),
> +					   GFP_NOFS);

Yeah, another mysterious calculation. Why do we add sizeof(u64) and sizeof(u32)
here?

Thanks,
Slava.

>  		if (err)
>  			goto out_err;
>  
> -		ceph_pagelist_encode_64(pagelist, ceph_ino(inode));
> -		ceph_pagelist_encode_string(pagelist, path, pathlen);
> -		ceph_pagelist_append(pagelist, &rec, sizeof(rec.v1));
> +		ceph_databuf_encode_64(dbuf, ceph_ino(inode));
> +		ceph_databuf_encode_string(dbuf, path, pathlen);
> +		ceph_databuf_append(dbuf, &rec, sizeof(rec.v1));
>  	}
>  
>  out_err:
> @@ -4760,12 +4759,12 @@ static int encode_snap_realms(struct ceph_mds_client *mdsc,
>  			      struct ceph_reconnect_state *recon_state)
>  {
>  	struct rb_node *p;
> -	struct ceph_pagelist *pagelist = recon_state->pagelist;
>  	struct ceph_client *cl = mdsc->fsc->client;
> +	struct ceph_databuf *dbuf = recon_state->dbuf;
>  	int err = 0;
>  
>  	if (recon_state->msg_version >= 4) {
> -		err = ceph_pagelist_encode_32(pagelist, mdsc->num_snap_realms);
> +		err = ceph_databuf_encode_32(dbuf, mdsc->num_snap_realms);
>  		if (err < 0)
>  			goto fail;
>  	}
> @@ -4784,20 +4783,20 @@ static int encode_snap_realms(struct ceph_mds_client *mdsc,
>  			size_t need = sizeof(u8) * 2 + sizeof(u32) +
>  				      sizeof(sr_rec);
>  
> -			if (pagelist->length + need > RECONNECT_MAX_SIZE) {
> +			if (ceph_databuf_len(dbuf) + need > RECONNECT_MAX_SIZE) {
>  				err = send_reconnect_partial(recon_state);
>  				if (err)
>  					goto fail;
> -				pagelist = recon_state->pagelist;
> +				dbuf = recon_state->dbuf;
>  			}
>  
> -			err = ceph_pagelist_reserve(pagelist, need);
> +			err = ceph_databuf_reserve(dbuf, need, GFP_NOFS);
>  			if (err)
>  				goto fail;
>  
> -			ceph_pagelist_encode_8(pagelist, 1);
> -			ceph_pagelist_encode_8(pagelist, 1);
> -			ceph_pagelist_encode_32(pagelist, sizeof(sr_rec));
> +			ceph_databuf_encode_8(dbuf, 1);
> +			ceph_databuf_encode_8(dbuf, 1);
> +			ceph_databuf_encode_32(dbuf, sizeof(sr_rec));
>  		}
>  
>  		doutc(cl, " adding snap realm %llx seq %lld parent %llx\n",
> @@ -4806,7 +4805,7 @@ static int encode_snap_realms(struct ceph_mds_client *mdsc,
>  		sr_rec.seq = cpu_to_le64(realm->seq);
>  		sr_rec.parent = cpu_to_le64(realm->parent_ino);
>  
> -		err = ceph_pagelist_append(pagelist, &sr_rec, sizeof(sr_rec));
> +		err = ceph_databuf_append(dbuf, &sr_rec, sizeof(sr_rec));
>  		if (err)
>  			goto fail;
>  
> @@ -4841,9 +4840,9 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
>  
>  	pr_info_client(cl, "mds%d reconnect start\n", mds);
>  
> -	recon_state.pagelist = ceph_pagelist_alloc(GFP_NOFS);
> -	if (!recon_state.pagelist)
> -		goto fail_nopagelist;
> +	recon_state.dbuf = ceph_databuf_req_alloc(1, 0, GFP_NOFS);
> +	if (!recon_state.dbuf)
> +		goto fail_nodatabuf;
>  
>  	reply = ceph_msg_new2(CEPH_MSG_CLIENT_RECONNECT, 0, 1, GFP_NOFS, false);
>  	if (!reply)
> @@ -4891,7 +4890,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
>  	down_read(&mdsc->snap_rwsem);
>  
>  	/* placeholder for nr_caps */
> -	err = ceph_pagelist_encode_32(recon_state.pagelist, 0);
> +	err = ceph_databuf_encode_32(recon_state.dbuf, 0);
>  	if (err)
>  		goto fail;
>  
> @@ -4916,7 +4915,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
>  	/* check if all realms can be encoded into current message */
>  	if (mdsc->num_snap_realms) {
>  		size_t total_len =
> -			recon_state.pagelist->length +
> +			ceph_databuf_len(recon_state.dbuf) +
>  			mdsc->num_snap_realms *
>  			sizeof(struct ceph_mds_snaprealm_reconnect);
>  		if (recon_state.msg_version >= 4) {
> @@ -4945,31 +4944,28 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
>  		goto fail;
>  
>  	if (recon_state.msg_version >= 5) {
> -		err = ceph_pagelist_encode_8(recon_state.pagelist, 0);
> +		err = ceph_databuf_encode_8(recon_state.dbuf, 0);
>  		if (err < 0)
>  			goto fail;
>  	}
>  
>  	if (recon_state.nr_caps || recon_state.nr_realms) {
> -		struct page *page =
> -			list_first_entry(&recon_state.pagelist->head,
> -					struct page, lru);
> -		__le32 *addr = kmap_atomic(page);
> +		__le32 *addr = kmap_ceph_databuf_page(recon_state.dbuf, 0);
>  		if (recon_state.nr_caps) {
>  			WARN_ON(recon_state.nr_realms != mdsc->num_snap_realms);
>  			*addr = cpu_to_le32(recon_state.nr_caps);
>  		} else if (recon_state.msg_version >= 4) {
>  			*(addr + 1) = cpu_to_le32(recon_state.nr_realms);
>  		}
> -		kunmap_atomic(addr);
> +		kunmap_local(addr);
>  	}
>  
>  	reply->hdr.version = cpu_to_le16(recon_state.msg_version);
>  	if (recon_state.msg_version >= 4)
>  		reply->hdr.compat_version = cpu_to_le16(4);
>  
> -	reply->hdr.data_len = cpu_to_le32(recon_state.pagelist->length);
> -	ceph_msg_data_add_pagelist(reply, recon_state.pagelist);
> +	reply->hdr.data_len = cpu_to_le32(ceph_databuf_len(recon_state.dbuf));
> +	ceph_msg_data_add_databuf(reply, recon_state.dbuf);
>  
>  	ceph_con_send(&session->s_con, reply);
>  
> @@ -4980,7 +4976,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
>  	mutex_unlock(&mdsc->mutex);
>  
>  	up_read(&mdsc->snap_rwsem);
> -	ceph_pagelist_release(recon_state.pagelist);
> +	ceph_databuf_release(recon_state.dbuf);
>  	return;
>  
>  fail:
> @@ -4988,8 +4984,8 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
>  	up_read(&mdsc->snap_rwsem);
>  	mutex_unlock(&session->s_mutex);
>  fail_nomsg:
> -	ceph_pagelist_release(recon_state.pagelist);
> -fail_nopagelist:
> +	ceph_databuf_release(recon_state.dbuf);
> +fail_nodatabuf:
>  	pr_err_client(cl, "error %d preparing reconnect for mds%d\n",
>  		      err, mds);
>  	return;
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 984a6d2a5378..b072572e2cf4 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -1351,9 +1351,9 @@ extern int ceph_encode_locks_to_buffer(struct inode *inode,
>  				       struct ceph_filelock *flocks,
>  				       int num_fcntl_locks,
>  				       int num_flock_locks);
> -extern int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
> -				  struct ceph_pagelist *pagelist,
> -				  int num_fcntl_locks, int num_flock_locks);
> +extern int ceph_locks_to_databuf(struct ceph_filelock *flocks,
> +				 struct ceph_databuf *dbuf,
> +				 int num_fcntl_locks, int num_flock_locks);
>  
>  /* debugfs.c */
>  extern void ceph_fs_debugfs_init(struct ceph_fs_client *client);
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index 6e126e212271..ce04205b8143 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -334,7 +334,7 @@ struct ceph_osd_linger_request {
>  	rados_watcherrcb_t errcb;
>  	void *data;
>  
> -	struct ceph_pagelist *request_pl;
> +	struct ceph_databuf *request_pl;
>  	struct ceph_databuf *notify_id_buf;
>  
>  	struct page ***preply_pages;
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index 64a06267e7b3..a967309d01a7 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -810,37 +810,37 @@ int osd_req_op_xattr_init(struct ceph_osd_request *osd_req, unsigned int which,
>  {
>  	struct ceph_osd_req_op *op = osd_req_op_init(osd_req, which,
>  						     opcode, 0);
> -	struct ceph_pagelist *pagelist;
> +	struct ceph_databuf *dbuf;
>  	size_t payload_len;
>  	int ret;
>  
>  	BUG_ON(opcode != CEPH_OSD_OP_SETXATTR && opcode != CEPH_OSD_OP_CMPXATTR);
>  
> -	pagelist = ceph_pagelist_alloc(GFP_NOFS);
> -	if (!pagelist)
> +	dbuf = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_NOFS);
> +	if (!dbuf)
>  		return -ENOMEM;
>  
>  	payload_len = strlen(name);
>  	op->xattr.name_len = payload_len;
> -	ret = ceph_pagelist_append(pagelist, name, payload_len);
> +	ret = ceph_databuf_append(dbuf, name, payload_len);
>  	if (ret)
> -		goto err_pagelist_free;
> +		goto err_databuf_free;
>  
>  	op->xattr.value_len = size;
> -	ret = ceph_pagelist_append(pagelist, value, size);
> +	ret = ceph_databuf_append(dbuf, value, size);
>  	if (ret)
> -		goto err_pagelist_free;
> +		goto err_databuf_free;
>  	payload_len += size;
>  
>  	op->xattr.cmp_op = cmp_op;
>  	op->xattr.cmp_mode = cmp_mode;
>  
> -	ceph_osd_data_pagelist_init(&op->xattr.osd_data, pagelist);
> +	ceph_osd_databuf_init(&op->xattr.osd_data, dbuf);
>  	op->indata_len = payload_len;
>  	return 0;
>  
> -err_pagelist_free:
> -	ceph_pagelist_release(pagelist);
> +err_databuf_free:
> +	ceph_databuf_release(dbuf);
>  	return ret;
>  }
>  EXPORT_SYMBOL(osd_req_op_xattr_init);
> @@ -864,15 +864,15 @@ static void osd_req_op_watch_init(struct ceph_osd_request *req, int which,
>   * encoded in @request_pl
>   */
>  static void osd_req_op_notify_init(struct ceph_osd_request *req, int which,
> -				   u64 cookie, struct ceph_pagelist *request_pl)
> +				   u64 cookie, struct ceph_databuf *request_pl)
>  {
>  	struct ceph_osd_req_op *op;
>  
>  	op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY, 0);
>  	op->notify.cookie = cookie;
>  
> -	ceph_osd_data_pagelist_init(&op->notify.request_data, request_pl);
> -	op->indata_len = request_pl->length;
> +	ceph_osd_databuf_init(&op->notify.request_data, request_pl);
> +	op->indata_len = ceph_databuf_len(request_pl);
>  }
>  
>  /*
> @@ -2730,8 +2730,7 @@ static void linger_release(struct kref *kref)
>  	WARN_ON(!list_empty(&lreq->pending_lworks));
>  	WARN_ON(lreq->osd);
>  
> -	if (lreq->request_pl)
> -		ceph_pagelist_release(lreq->request_pl);
> +	ceph_databuf_release(lreq->request_pl);
>  	ceph_databuf_release(lreq->notify_id_buf);
>  	ceph_osdc_put_request(lreq->reg_req);
>  	ceph_osdc_put_request(lreq->ping_req);
> @@ -4800,30 +4799,30 @@ static int osd_req_op_notify_ack_init(struct ceph_osd_request *req, int which,
>  				      u32 payload_len)
>  {
>  	struct ceph_osd_req_op *op;
> -	struct ceph_pagelist *pl;
> +	struct ceph_databuf *dbuf;
>  	int ret;
>  
>  	op = osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY_ACK, 0);
>  
> -	pl = ceph_pagelist_alloc(GFP_NOIO);
> -	if (!pl)
> +	dbuf = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_NOIO);
> +	if (!dbuf)
>  		return -ENOMEM;
>  
> -	ret = ceph_pagelist_encode_64(pl, notify_id);
> -	ret |= ceph_pagelist_encode_64(pl, cookie);
> +	ret = ceph_databuf_encode_64(dbuf, notify_id);
> +	ret |= ceph_databuf_encode_64(dbuf, cookie);
>  	if (payload) {
> -		ret |= ceph_pagelist_encode_32(pl, payload_len);
> -		ret |= ceph_pagelist_append(pl, payload, payload_len);
> +		ret |= ceph_databuf_encode_32(dbuf, payload_len);
> +		ret |= ceph_databuf_append(dbuf, payload, payload_len);
>  	} else {
> -		ret |= ceph_pagelist_encode_32(pl, 0);
> +		ret |= ceph_databuf_encode_32(dbuf, 0);
>  	}
>  	if (ret) {
> -		ceph_pagelist_release(pl);
> +		ceph_databuf_release(dbuf);
>  		return -ENOMEM;
>  	}
>  
> -	ceph_osd_data_pagelist_init(&op->notify_ack.request_data, pl);
> -	op->indata_len = pl->length;
> +	ceph_osd_databuf_init(&op->notify_ack.request_data, dbuf);
> +	op->indata_len = ceph_databuf_len(dbuf);
>  	return 0;
>  }
>  
> @@ -4894,16 +4893,16 @@ int ceph_osdc_notify(struct ceph_osd_client *osdc,
>  	if (!lreq)
>  		return -ENOMEM;
>  
> -	lreq->request_pl = ceph_pagelist_alloc(GFP_NOIO);
> +	lreq->request_pl = ceph_databuf_req_alloc(1, PAGE_SIZE, GFP_NOIO);
>  	if (!lreq->request_pl) {
>  		ret = -ENOMEM;
>  		goto out_put_lreq;
>  	}
>  
> -	ret = ceph_pagelist_encode_32(lreq->request_pl, 1); /* prot_ver */
> -	ret |= ceph_pagelist_encode_32(lreq->request_pl, timeout);
> -	ret |= ceph_pagelist_encode_32(lreq->request_pl, payload_len);
> -	ret |= ceph_pagelist_append(lreq->request_pl, payload, payload_len);
> +	ret = ceph_databuf_encode_32(lreq->request_pl, 1); /* prot_ver */
> +	ret |= ceph_databuf_encode_32(lreq->request_pl, timeout);
> +	ret |= ceph_databuf_encode_32(lreq->request_pl, payload_len);
> +	ret |= ceph_databuf_append(lreq->request_pl, payload, payload_len);
>  	if (ret) {
>  		ret = -ENOMEM;
>  		goto out_put_lreq;
> 
>