fs/orangefs/dir.c - linux - Git at Google

 // 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_shared = orangefs_dir_iterate,
 	.open = orangefs_dir_open,
 	.release = orangefs_dir_release
 };
	// 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_shared = orangefs_dir_iterate,
	.open = orangefs_dir_open,
	.release = orangefs_dir_release
	};