1 files changed, 404 insertions, 0 deletions

diff --git a/fs/orangefs/dir.c b/fs/orangefs/dir.c
new file mode 100644
index 000000000..e2c2699d8
--- /dev/null
+++ b/fs/orangefs/dir.c
@@ -0,0 +1,404 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2017 Omnibond Systems, L.L.C.
+ */
+
+#include "protocol.h"
+#include "orangefs-kernel.h"
+#include "orangefs-bufmap.h"
+
+struct orangefs_dir_part {
+	struct orangefs_dir_part *next;
+	size_t len;
+};
+
+struct orangefs_dir {
+	__u64 token;
+	struct orangefs_dir_part *part;
+	loff_t end;
+	int error;
+};
+
+#define PART_SHIFT (24)
+#define PART_SIZE (1<<24)
+#define PART_MASK (~(PART_SIZE - 1))
+
+/*
+ * There can be up to 512 directory entries.  Each entry is encoded as
+ * follows:
+ * 4 bytes: string size (n)
+ * n bytes: string
+ * 1 byte: trailing zero
+ * padding to 8 bytes
+ * 16 bytes: khandle
+ * padding to 8 bytes
+ *
+ * The trailer_buf starts with a struct orangefs_readdir_response_s
+ * which must be skipped to get to the directory data.
+ *
+ * The data which is received from the userspace daemon is termed a
+ * part and is stored in a linked list in case more than one part is
+ * needed for a large directory.
+ *
+ * The position pointer (ctx->pos) encodes the part and offset on which
+ * to begin reading at.  Bits above PART_SHIFT encode the part and bits
+ * below PART_SHIFT encode the offset.  Parts are stored in a linked
+ * list which grows as data is received from the server.  The overhead
+ * associated with managing the list is presumed to be small compared to
+ * the overhead of communicating with the server.
+ *
+ * As data is received from the server, it is placed at the end of the
+ * part list.  Data is parsed from the current position as it is needed.
+ * When data is determined to be corrupt, it is either because the
+ * userspace component has sent back corrupt data or because the file
+ * pointer has been moved to an invalid location.  Since the two cannot
+ * be differentiated, return EIO.
+ *
+ * Part zero is synthesized to contains `.' and `..'.  Part one is the
+ * first part of the part list.
+ */
+
+static int do_readdir(struct orangefs_inode_s *oi,
+    struct orangefs_dir *od, struct dentry *dentry,
+    struct orangefs_kernel_op_s *op)
+{
+	struct orangefs_readdir_response_s *resp;
+	int bufi, r;
+
+	/*
+	 * Despite the badly named field, readdir does not use shared
+	 * memory.  However, there are a limited number of readdir
+	 * slots, which must be allocated here.  This flag simply tells
+	 * the op scheduler to return the op here for retry.
+	 */
+	op->uses_shared_memory = 1;
+	op->upcall.req.readdir.refn = oi->refn;
+	op->upcall.req.readdir.token = od->token;
+	op->upcall.req.readdir.max_dirent_count =
+	    ORANGEFS_MAX_DIRENT_COUNT_READDIR;
+
+again:
+	bufi = orangefs_readdir_index_get();
+	if (bufi < 0) {
+		od->error = bufi;
+		return bufi;
+	}
+
+	op->upcall.req.readdir.buf_index = bufi;
+
+	r = service_operation(op, "orangefs_readdir",
+	    get_interruptible_flag(dentry->d_inode));
+
+	orangefs_readdir_index_put(bufi);
+
+	if (op_state_purged(op)) {
+		if (r == -EAGAIN) {
+			vfree(op->downcall.trailer_buf);
+			goto again;
+		} else if (r == -EIO) {
+			vfree(op->downcall.trailer_buf);
+			od->error = r;
+			return r;
+		}
+	}
+
+	if (r < 0) {
+		vfree(op->downcall.trailer_buf);
+		od->error = r;
+		return r;
+	} else if (op->downcall.status) {
+		vfree(op->downcall.trailer_buf);
+		od->error = op->downcall.status;
+		return op->downcall.status;
+	}
+
+	/*
+	 * The maximum size is size per entry times the 512 entries plus
+	 * the header.  This is well under the limit.
+	 */
+	if (op->downcall.trailer_size > PART_SIZE) {
+		vfree(op->downcall.trailer_buf);
+		od->error = -EIO;
+		return -EIO;
+	}
+
+	resp = (struct orangefs_readdir_response_s *)
+	    op->downcall.trailer_buf;
+	od->token = resp->token;
+	return 0;
+}
+
+static int parse_readdir(struct orangefs_dir *od,
+    struct orangefs_kernel_op_s *op)
+{
+	struct orangefs_dir_part *part, *new;
+	size_t count;
+
+	count = 1;
+	part = od->part;
+	while (part) {
+		count++;
+		if (part->next)
+			part = part->next;
+		else
+			break;
+	}
+
+	new = (void *)op->downcall.trailer_buf;
+	new->next = NULL;
+	new->len = op->downcall.trailer_size -
+	    sizeof(struct orangefs_readdir_response_s);
+	if (!od->part)
+		od->part = new;
+	else
+		part->next = new;
+	count++;
+	od->end = count << PART_SHIFT;
+
+	return 0;
+}
+
+static int orangefs_dir_more(struct orangefs_inode_s *oi,
+    struct orangefs_dir *od, struct dentry *dentry)
+{
+	struct orangefs_kernel_op_s *op;
+	int r;
+
+	op = op_alloc(ORANGEFS_VFS_OP_READDIR);
+	if (!op) {
+		od->error = -ENOMEM;
+		return -ENOMEM;
+	}
+	r = do_readdir(oi, od, dentry, op);
+	if (r) {
+		od->error = r;
+		goto out;
+	}
+	r = parse_readdir(od, op);
+	if (r) {
+		od->error = r;
+		goto out;
+	}
+
+	od->error = 0;
+out:
+	op_release(op);
+	return od->error;
+}
+
+static int fill_from_part(struct orangefs_dir_part *part,
+    struct dir_context *ctx)
+{
+	const int offset = sizeof(struct orangefs_readdir_response_s);
+	struct orangefs_khandle *khandle;
+	__u32 *len, padlen;
+	loff_t i;
+	char *s;
+	i = ctx->pos & ~PART_MASK;
+
+	/* The file offset from userspace is too large. */
+	if (i > part->len)
+		return 1;
+
+	/*
+	 * If the seek pointer is positioned just before an entry it
+	 * should find the next entry.
+	 */
+	if (i % 8)
+		i = i + (8 - i%8)%8;
+
+	while (i < part->len) {
+		if (part->len < i + sizeof *len)
+			break;
+		len = (void *)part + offset + i;
+		/*
+		 * len is the size of the string itself.  padlen is the
+		 * total size of the encoded string.
+		 */
+		padlen = (sizeof *len + *len + 1) +
+		    (8 - (sizeof *len + *len + 1)%8)%8;
+		if (part->len < i + padlen + sizeof *khandle)
+			goto next;
+		s = (void *)part + offset + i + sizeof *len;
+		if (s[*len] != 0)
+			goto next;
+		khandle = (void *)part + offset + i + padlen;
+		if (!dir_emit(ctx, s, *len,
+		    orangefs_khandle_to_ino(khandle),
+		    DT_UNKNOWN))
+			return 0;
+		i += padlen + sizeof *khandle;
+		i = i + (8 - i%8)%8;
+		BUG_ON(i > part->len);
+		ctx->pos = (ctx->pos & PART_MASK) | i;
+		continue;
+next:
+		i += 8;
+	}
+	return 1;
+}
+
+static int orangefs_dir_fill(struct orangefs_inode_s *oi,
+    struct orangefs_dir *od, struct dentry *dentry,
+    struct dir_context *ctx)
+{
+	struct orangefs_dir_part *part;
+	size_t count;
+
+	count = ((ctx->pos & PART_MASK) >> PART_SHIFT) - 1;
+
+	part = od->part;
+	while (part->next && count) {
+		count--;
+		part = part->next;
+	}
+	/* This means the userspace file offset is invalid. */
+	if (count) {
+		od->error = -EIO;
+		return -EIO;
+	}
+
+	while (part && part->len) {
+		int r;
+		r = fill_from_part(part, ctx);
+		if (r < 0) {
+			od->error = r;
+			return r;
+		} else if (r == 0) {
+			/* Userspace buffer is full. */
+			break;
+		} else {
+			/*
+			 * The part ran out of data.  Move to the next
+			 * part. */
+			ctx->pos = (ctx->pos & PART_MASK) +
+			    (1 << PART_SHIFT);
+			part = part->next;
+		}
+	}
+	return 0;
+}
+
+static loff_t orangefs_dir_llseek(struct file *file, loff_t offset,
+    int whence)
+{
+	struct orangefs_dir *od = file->private_data;
+	/*
+	 * Delete the stored data so userspace sees new directory
+	 * entries.
+	 */
+	if (!whence && offset < od->end) {
+		struct orangefs_dir_part *part = od->part;
+		while (part) {
+			struct orangefs_dir_part *next = part->next;
+			vfree(part);
+			part = next;
+		}
+		od->token = ORANGEFS_ITERATE_START;
+		od->part = NULL;
+		od->end = 1 << PART_SHIFT;
+	}
+	return default_llseek(file, offset, whence);
+}
+
+static int orangefs_dir_iterate(struct file *file,
+    struct dir_context *ctx)
+{
+	struct orangefs_inode_s *oi;
+	struct orangefs_dir *od;
+	struct dentry *dentry;
+	int r;
+
+	dentry = file->f_path.dentry;
+	oi = ORANGEFS_I(dentry->d_inode);
+	od = file->private_data;
+
+	if (od->error)
+		return od->error;
+
+	if (ctx->pos == 0) {
+		if (!dir_emit_dot(file, ctx))
+			return 0;
+		ctx->pos++;
+	}
+	if (ctx->pos == 1) {
+		if (!dir_emit_dotdot(file, ctx))
+			return 0;
+		ctx->pos = 1 << PART_SHIFT;
+	}
+
+	/*
+	 * The seek position is in the first synthesized part but is not
+	 * valid.
+	 */
+	if ((ctx->pos & PART_MASK) == 0)
+		return -EIO;
+
+	r = 0;
+
+	/*
+	 * Must read more if the user has sought past what has been read
+	 * so far.  Stop a user who has sought past the end.
+	 */
+	while (od->token != ORANGEFS_ITERATE_END &&
+	    ctx->pos > od->end) {
+		r = orangefs_dir_more(oi, od, dentry);
+		if (r)
+			return r;
+	}
+	if (od->token == ORANGEFS_ITERATE_END && ctx->pos > od->end)
+		return -EIO;
+
+	/* Then try to fill if there's any left in the buffer. */
+	if (ctx->pos < od->end) {
+		r = orangefs_dir_fill(oi, od, dentry, ctx);
+		if (r)
+			return r;
+	}
+
+	/* Finally get some more and try to fill. */
+	if (od->token != ORANGEFS_ITERATE_END) {
+		r = orangefs_dir_more(oi, od, dentry);
+		if (r)
+			return r;
+		r = orangefs_dir_fill(oi, od, dentry, ctx);
+	}
+
+	return r;
+}
+
+static int orangefs_dir_open(struct inode *inode, struct file *file)
+{
+	struct orangefs_dir *od;
+	file->private_data = kmalloc(sizeof(struct orangefs_dir),
+	    GFP_KERNEL);
+	if (!file->private_data)
+		return -ENOMEM;
+	od = file->private_data;
+	od->token = ORANGEFS_ITERATE_START;
+	od->part = NULL;
+	od->end = 1 << PART_SHIFT;
+	od->error = 0;
+	return 0;
+}
+
+static int orangefs_dir_release(struct inode *inode, struct file *file)
+{
+	struct orangefs_dir *od = file->private_data;
+	struct orangefs_dir_part *part = od->part;
+	while (part) {
+		struct orangefs_dir_part *next = part->next;
+		vfree(part);
+		part = next;
+	}
+	kfree(od);
+	return 0;
+}
+
+const struct file_operations orangefs_dir_operations = {
+	.llseek = orangefs_dir_llseek,
+	.read = generic_read_dir,
+	.iterate = orangefs_dir_iterate,
+	.open = orangefs_dir_open,
+	.release = orangefs_dir_release
+};