fs/9p/vfs_dir.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/9p/vfs_dir.c
   4  *
   5  * This file contains vfs directory ops for the 9P2000 protocol.
   6  *
   7  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   8  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/errno.h>
  13 #include <linux/fs.h>
  14 #include <linux/file.h>
  15 #include <linux/stat.h>
  16 #include <linux/string.h>
  17 #include <linux/sched.h>
  18 #include <linux/inet.h>
  19 #include <linux/idr.h>
  20 #include <linux/slab.h>
  21 #include <linux/uio.h>
  22 #include <net/9p/9p.h>
  23 #include <net/9p/client.h>
  24
  25 #include "v9fs.h"
  26 #include "v9fs_vfs.h"
  27 #include "fid.h"
  28
  29 /**
  30  * struct p9_rdir - readdir accounting
  31  * @head: start offset of current dirread buffer
  32  * @tail: end offset of current dirread buffer
  33  * @buf: dirread buffer
  34  *
  35  * private structure for keeping track of readdir
  36  * allocated on demand
  37  */
  38
  39 struct p9_rdir {
  40         int head;
  41         int tail;
  42         uint8_t buf[];
  43 };
  44
  45 /**
  46  * dt_type - return file type
  47  * @mistat: mistat structure
  48  *
  49  */
  50
  51 static inline int dt_type(struct p9_wstat *mistat)
  52 {
  53         unsigned long perm = mistat->mode;
  54         int rettype = DT_REG;
  55
  56         if (perm & P9_DMDIR)
  57                 rettype = DT_DIR;
  58         if (perm & P9_DMSYMLINK)
  59                 rettype = DT_LNK;
  60
  61         return rettype;
  62 }
  63
  64 /**
  65  * v9fs_alloc_rdir_buf - Allocate buffer used for read and readdir
  66  * @filp: opened file structure
  67  * @buflen: Length in bytes of buffer to allocate
  68  *
  69  */
  70
  71 static struct p9_rdir *v9fs_alloc_rdir_buf(struct file *filp, int buflen)
  72 {
  73         struct p9_fid *fid = filp->private_data;
  74         if (!fid->rdir)
  75                 fid->rdir = kzalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);
  76         return fid->rdir;
  77 }
  78
  79 /**
  80  * v9fs_dir_readdir - iterate through a directory
  81  * @file: opened file structure
  82  * @ctx: actor we feed the entries to
  83  *
  84  */
  85
  86 static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
  87 {
  88         bool over;
  89         struct p9_wstat st;
  90         int err = 0;
  91         struct p9_fid *fid;
  92         int buflen;
  93         struct p9_rdir *rdir;
  94         struct kvec kvec;
  95
  96         p9_debug(P9_DEBUG_VFS, "name %pD\n", file);
  97         fid = file->private_data;
  98
  99         buflen = fid->clnt->msize - P9_IOHDRSZ;
 100
 101         rdir = v9fs_alloc_rdir_buf(file, buflen);
 102         if (!rdir)
 103                 return -ENOMEM;
 104         kvec.iov_base = rdir->buf;
 105         kvec.iov_len = buflen;
 106
 107         while (1) {
 108                 if (rdir->tail == rdir->head) {
 109                         struct iov_iter to;
 110                         int n;
 111                         iov_iter_kvec(&to, READ, &kvec, 1, buflen);
 112                         n = p9_client_read(file->private_data, ctx->pos, &to,
 113                                            &err);
 114                         if (err)
 115                                 return err;
 116                         if (n == 0)
 117                                 return 0;
 118
 119                         rdir->head = 0;
 120                         rdir->tail = n;
 121                 }
 122                 while (rdir->head < rdir->tail) {
 123                         err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
 124                                           rdir->tail - rdir->head, &st);
 125                         if (err <= 0) {
 126                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
 127                                 return -EIO;
 128                         }
 129
 130                         over = !dir_emit(ctx, st.name, strlen(st.name),
 131                                          v9fs_qid2ino(&st.qid), dt_type(&st));
 132                         p9stat_free(&st);
 133                         if (over)
 134                                 return 0;
 135
 136                         rdir->head += err;
 137                         ctx->pos += err;
 138                 }
 139         }
 140 }
 141
 142 /**
 143  * v9fs_dir_readdir_dotl - iterate through a directory
 144  * @file: opened file structure
 145  * @ctx: actor we feed the entries to
 146  *
 147  */
 148 static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 149 {
 150         int err = 0;
 151         struct p9_fid *fid;
 152         int buflen;
 153         struct p9_rdir *rdir;
 154         struct p9_dirent curdirent;
 155
 156         p9_debug(P9_DEBUG_VFS, "name %pD\n", file);
 157         fid = file->private_data;
 158
 159         buflen = fid->clnt->msize - P9_READDIRHDRSZ;
 160
 161         rdir = v9fs_alloc_rdir_buf(file, buflen);
 162         if (!rdir)
 163                 return -ENOMEM;
 164
 165         while (1) {
 166                 if (rdir->tail == rdir->head) {
 167                         err = p9_client_readdir(fid, rdir->buf, buflen,
 168                                                 ctx->pos);
 169                         if (err <= 0)
 170                                 return err;
 171
 172                         rdir->head = 0;
 173                         rdir->tail = err;
 174                 }
 175
 176                 while (rdir->head < rdir->tail) {
 177
 178                         err = p9dirent_read(fid->clnt, rdir->buf + rdir->head,
 179                                             rdir->tail - rdir->head,
 180                                             &curdirent);
 181                         if (err < 0) {
 182                                 p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
 183                                 return -EIO;
 184                         }
 185
 186                         if (!dir_emit(ctx, curdirent.d_name,
 187                                       strlen(curdirent.d_name),
 188                                       v9fs_qid2ino(&curdirent.qid),
 189                                       curdirent.d_type))
 190                                 return 0;
 191
 192                         ctx->pos = curdirent.d_off;
 193                         rdir->head += err;
 194                 }
 195         }
 196 }
 197
 198
 199 /**
 200  * v9fs_dir_release - close a directory
 201  * @inode: inode of the directory
 202  * @filp: file pointer to a directory
 203  *
 204  */
 205
 206 int v9fs_dir_release(struct inode *inode, struct file *filp)
 207 {
 208         struct p9_fid *fid;
 209
 210         fid = filp->private_data;
 211         p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
 212                  inode, filp, fid ? fid->fid : -1);
 213         if (fid) {
 214                 spin_lock(&inode->i_lock);
 215                 hlist_del(&fid->ilist);
 216                 spin_unlock(&inode->i_lock);
 217                 p9_client_clunk(fid);
 218         }
 219         return 0;
 220 }
 221
 222 const struct file_operations v9fs_dir_operations = {
 223         .read = generic_read_dir,
 224         .llseek = generic_file_llseek,
 225         .iterate_shared = v9fs_dir_readdir,
 226         .open = v9fs_file_open,
 227         .release = v9fs_dir_release,
 228 };
 229
 230 const struct file_operations v9fs_dir_operations_dotl = {
 231         .read = generic_read_dir,
 232         .llseek = generic_file_llseek,
 233         .iterate_shared = v9fs_dir_readdir_dotl,
 234         .open = v9fs_file_open,
 235         .release = v9fs_dir_release,
 236         .fsync = v9fs_file_fsync_dotl,
 237 };