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Commit 81c6aea5 authored by Yan, Zheng's avatar Yan, Zheng Committed by Sage Weil
Browse files

ceph: handle frag mismatch between readdir request and reply 



If client has outdated directory fragments information, it may request
readdir an non-existent directory fragment. In this case, the MDS finds
an approximate directory fragment and sends its contents back to the
client. When receiving a reply with fragment that is different than the
requested one, the client need to reset the 'readdir offset'.

Signed-off-by: default avatarYan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent 53e879a4

fs/ceph/dir.c

+10 −1
Original line number Diff line number Diff line
@@ -352,8 +352,18 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx) 
		}



		/* note next offset and last dentry name */

		rinfo = &req->r_reply_info;

		if (le32_to_cpu(rinfo->dir_dir->frag) != frag) {

			frag = le32_to_cpu(rinfo->dir_dir->frag);

			if (ceph_frag_is_leftmost(frag))

				fi->next_offset = 2;

			else

				fi->next_offset = 0;

			off = fi->next_offset;

		}

		fi->offset = fi->next_offset;

		fi->last_readdir = req;

		fi->frag = frag;



		if (req->r_reply_info.dir_end) {

			kfree(fi->last_name);
@@ -363,7 +373,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx) 
			else

				fi->next_offset = 0;

		} else {

			rinfo = &req->r_reply_info;

			err = note_last_dentry(fi,

				       rinfo->dir_dname[rinfo->dir_nr-1],

				       rinfo->dir_dname_len[rinfo->dir_nr-1]);

fs/ceph/inode.c

+14 −2
Original line number Diff line number Diff line
@@ -1275,8 +1275,20 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req, 
	int err = 0, i;

	struct inode *snapdir = NULL;

	struct ceph_mds_request_head *rhead = req->r_request->front.iov_base;

	u64 frag = le32_to_cpu(rhead->args.readdir.frag);

	struct ceph_dentry_info *di;

	u64 r_readdir_offset = req->r_readdir_offset;

	u32 frag = le32_to_cpu(rhead->args.readdir.frag);



	if (rinfo->dir_dir &&

	    le32_to_cpu(rinfo->dir_dir->frag) != frag) {

		dout("readdir_prepopulate got new frag %x -> %x\n",

		     frag, le32_to_cpu(rinfo->dir_dir->frag));

		frag = le32_to_cpu(rinfo->dir_dir->frag);

		if (ceph_frag_is_leftmost(frag))

			r_readdir_offset = 2;

		else

			r_readdir_offset = 0;

	}



	if (req->r_aborted)

		return readdir_prepopulate_inodes_only(req, session);
@@ -1340,7 +1352,7 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req, 
		}



		di = dn->d_fsdata;

		di->offset = ceph_make_fpos(frag, i + req->r_readdir_offset);

		di->offset = ceph_make_fpos(frag, i + r_readdir_offset);



		/* inode */

		if (dn->d_inode) {

fs/ceph/mds_client.c

+1 −2
Original line number Diff line number Diff line
@@ -2238,8 +2238,7 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg) 
	err = ceph_fill_trace(mdsc->fsc->sb, req, req->r_session);

	if (err == 0) {

		if (result == 0 && (req->r_op == CEPH_MDS_OP_READDIR ||

				    req->r_op == CEPH_MDS_OP_LSSNAP) &&

		    rinfo->dir_nr)

				    req->r_op == CEPH_MDS_OP_LSSNAP))

			ceph_readdir_prepopulate(req, req->r_session);

		ceph_unreserve_caps(mdsc, &req->r_caps_reservation);

	}