// 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_dir *od, struct inode *inode,
struct orangefs_kernel_op_s *op)
{
struct orangefs_inode_s *oi = ORANGEFS_I(inode);
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(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_dir *od, struct inode *inode)
{
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(od, inode, 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_dir *od, 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_dir *od = file->private_data;
struct inode *inode = file_inode(file);
int r;
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(od, inode);
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(od, ctx);
if (r)
return r;
}
/* Finally get some more and try to fill. */
if (od->token != ORANGEFS_ITERATE_END) {
r = orangefs_dir_more(od, inode);
if (r)
return r;
r = orangefs_dir_fill(od, 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
};
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