ceph: record 'offset' for each entry of readdir result

This is preparation for using hash value as dentry 'offset'
Signed-off-by: Yan, Zheng <zyan@redhat.com>

fs/ceph/dir.c

@@ -277,12 +277,12 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	struct ceph_mds_client *mdsc = fsc->mdsc;
 	unsigned frag = fpos_frag(ctx->pos);
-	int off = fpos_off(ctx->pos);
+	int i;
 	int err;
 	u32 ftype;
 	struct ceph_mds_reply_info_parsed *rinfo;
 
-	dout("readdir %p file %p frag %u off %u\n", inode, file, frag, off);
+	dout("readdir %p file %p pos %llx\n", inode, file, ctx->pos);
 	if (fi->flags & CEPH_F_ATEND)
 		return 0;
 
@@ -294,7 +294,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 			    inode->i_mode >> 12))
 			return 0;
 		ctx->pos = 1;
-		off = 1;
 	}
 	if (ctx->pos == 1) {
 		ino_t ino = parent_ino(file->f_path.dentry);
@@ -304,7 +303,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 			    inode->i_mode >> 12))
 			return 0;
 		ctx->pos = 2;
-		off = 2;
 	}
 
 	/* can we use the dcache? */
@@ -320,7 +318,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 		if (err != -EAGAIN)
 			return err;
 		frag = fpos_frag(ctx->pos);
-		off = fpos_off(ctx->pos);
 	} else {
 		spin_unlock(&ci->i_ceph_lock);
 	}
@@ -386,12 +383,12 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 		rinfo = &req->r_reply_info;
 		if (le32_to_cpu(rinfo->dir_dir->frag) != frag) {
 			frag = le32_to_cpu(rinfo->dir_dir->frag);
-			off = req->r_readdir_offset;
-			fi->next_offset = off;
+			fi->next_offset = req->r_readdir_offset;
+			/* adjust ctx->pos to beginning of frag */
+			ctx->pos = ceph_make_fpos(frag, fi->next_offset);
 		}
 
 		fi->frag = frag;
-		fi->offset = fi->next_offset;
 		fi->last_readdir = req;
 
 		if (req->r_did_prepopulate) {
@@ -399,7 +396,8 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 			if (fi->readdir_cache_idx < 0) {
 				/* preclude from marking dir ordered */
 				fi->dir_ordered_count = 0;
-			} else if (ceph_frag_is_leftmost(frag) && off == 2) {
+			} else if (ceph_frag_is_leftmost(frag) &&
+				   fi->next_offset == 2) {
 				/* note dir version at start of readdir so
 				 * we can tell if any dentries get dropped */
 				fi->dir_release_count = req->r_dir_release_cnt;
@@ -421,37 +419,54 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 			struct ceph_mds_reply_dir_entry *rde =
 					rinfo->dir_entries + (rinfo->dir_nr-1);
 			err = note_last_dentry(fi, rde->name, rde->name_len,
-				       fi->next_offset + rinfo->dir_nr);
+					       fpos_off(rde->offset) + 1);
 			if (err)
 				return err;
 		}
 	}
 
 	rinfo = &fi->last_readdir->r_reply_info;
-	dout("readdir frag %x num %d off %d chunkoff %d\n", frag,
-	     rinfo->dir_nr, off, fi->offset);
+	dout("readdir frag %x num %d pos %llx chunk first %llx\n",
+	     frag, rinfo->dir_nr, ctx->pos,
+	     rinfo->dir_nr ? rinfo->dir_entries[0].offset : 0LL);
 
-	ctx->pos = ceph_make_fpos(frag, off);
-	while (off >= fi->offset && off - fi->offset < rinfo->dir_nr) {
-		struct ceph_mds_reply_dir_entry *rde =
-			rinfo->dir_entries + (off - fi->offset);
+	i = 0;
+	/* search start position */
+	if (rinfo->dir_nr > 0) {
+		int step, nr = rinfo->dir_nr;
+		while (nr > 0) {
+			step = nr >> 1;
+			if (rinfo->dir_entries[i + step].offset < ctx->pos) {
+				i +=  step + 1;
+				nr -= step + 1;
+			} else {
+				nr = step;
+			}
+		}
+	}
+	for (; i < rinfo->dir_nr; i++) {
+		struct ceph_mds_reply_dir_entry *rde = rinfo->dir_entries + i;
 		struct ceph_vino vino;
 		ino_t ino;
 
-		dout("readdir off %d (%d/%d) -> %lld '%.*s' %p\n",
-		     off, off - fi->offset, rinfo->dir_nr, ctx->pos,
+		BUG_ON(rde->offset < ctx->pos);
+
+		ctx->pos = rde->offset;
+		dout("readdir (%d/%d) -> %llx '%.*s' %p\n",
+		     i, rinfo->dir_nr, ctx->pos,
 		     rde->name_len, rde->name, &rde->inode.in);
+
 		BUG_ON(!rde->inode.in);
 		ftype = le32_to_cpu(rde->inode.in->mode) >> 12;
 		vino.ino = le64_to_cpu(rde->inode.in->ino);
 		vino.snap = le64_to_cpu(rde->inode.in->snapid);
 		ino = ceph_vino_to_ino(vino);
+
 		if (!dir_emit(ctx, rde->name, rde->name_len,
 			      ceph_translate_ino(inode->i_sb, ino), ftype)) {
 			dout("filldir stopping us...\n");
 			return 0;
 		}
-		off++;
 		ctx->pos++;
 	}
 
@@ -464,8 +479,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 	/* more frags? */
 	if (!ceph_frag_is_rightmost(frag)) {
 		frag = ceph_frag_next(frag);
-		off = 2;
-		ctx->pos = ceph_make_fpos(frag, off);
+		ctx->pos = ceph_make_fpos(frag, 2);
 		dout("readdir next frag is %x\n", frag);
 		goto more;
 	}
@@ -497,7 +511,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 	return 0;
 }
 
-static void reset_readdir(struct ceph_file_info *fi, unsigned frag)
+static void reset_readdir(struct ceph_file_info *fi)
 {
 	if (fi->last_readdir) {
 		ceph_mdsc_put_request(fi->last_readdir);
@@ -511,6 +525,23 @@ static void reset_readdir(struct ceph_file_info *fi, unsigned frag)
 	fi->flags &= ~CEPH_F_ATEND;
 }
 
+/*
+ * discard buffered readdir content on seekdir(0), or seek to new frag,
+ * or seek prior to current chunk
+ */
+static bool need_reset_readdir(struct ceph_file_info *fi, loff_t new_pos)
+{
+	struct ceph_mds_reply_info_parsed *rinfo;
+	if (new_pos == 0)
+		return true;
+	if (fpos_frag(new_pos) != fi->frag)
+		return true;
+	rinfo = fi->last_readdir ? &fi->last_readdir->r_reply_info : NULL;
+	if (!rinfo || !rinfo->dir_nr)
+		return true;
+	return new_pos < rinfo->dir_entries[0].offset;;
+}
+
 static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct ceph_file_info *fi = file->private_data;
@@ -539,13 +570,9 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence)
 		}
 		retval = offset;
 
-		if (offset == 0 ||
-		    fpos_frag(offset) != fi->frag ||
-		    fpos_off(offset) < fi->offset) {
-			/* discard buffered readdir content on seekdir(0), or
-			 * seek to new frag, or seek prior to current chunk */
+		if (need_reset_readdir(fi, offset)) {
 			dout("dir_llseek dropping %p content\n", file);
-			reset_readdir(fi, fpos_frag(offset));
+			reset_readdir(fi);
 		} else if (fpos_cmp(offset, old_offset) > 0) {
 			/* reset dir_release_count if we did a forward seek */
 			fi->dir_release_count = 0;

fs/ceph/inode.c

@@ -1523,6 +1523,7 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
 
 		di = dn->d_fsdata;
 		di->offset = ceph_make_fpos(frag, i + req->r_readdir_offset);
+		rde->offset = di->offset;
 
 		update_dentry_lease(dn, rde->lease, req->r_session,
 				    req->r_request_started);

fs/ceph/mds_client.c

@@ -214,6 +214,8 @@ static int parse_reply_info_dir(void **p, void *end,
 		err = parse_reply_info_in(p, end, &rde->inode, features);
 		if (err < 0)
 			goto out_bad;
+		/* ceph_readdir_prepopulate() will update it */
+		rde->offset = 0;
 		i++;
 		num--;
 	}

fs/ceph/mds_client.h

@@ -52,6 +52,7 @@ struct ceph_mds_reply_dir_entry {
 	u32                           name_len;
 	struct ceph_mds_reply_lease   *lease;
 	struct ceph_mds_reply_info_in inode;
+	loff_t			      offset;
 };
 
 /*

fs/ceph/super.h

@@ -635,7 +635,6 @@ struct ceph_file_info {
 	struct ceph_mds_request *last_readdir;
 
 	/* readdir: position within a frag */
-	unsigned offset;       /* offset of last chunk, adjusted for . and .. */
 	unsigned next_offset;  /* offset of next chunk (last_name's + 1) */
 	char *last_name;       /* last entry in previous chunk */
 	long long dir_release_count;