fs/9p/vfs_file.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * This file contians vfs file ops for 9P2000.
   4  *
   5  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   6  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/errno.h>
  11 #include <linux/fs.h>
  12 #include <linux/filelock.h>
  13 #include <linux/sched.h>
  14 #include <linux/file.h>
  15 #include <linux/stat.h>
  16 #include <linux/string.h>
  17 #include <linux/list.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/utsname.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/uio.h>
  22 #include <linux/slab.h>
  23 #include <net/9p/9p.h>
  24 #include <net/9p/client.h>
  25
  26 #include "v9fs.h"
  27 #include "v9fs_vfs.h"
  28 #include "fid.h"
  29 #include "cache.h"
  30
  31 static const struct vm_operations_struct v9fs_mmap_file_vm_ops;
  32
  33 /**
  34  * v9fs_file_open - open a file (or directory)
  35  * @inode: inode to be opened
  36  * @file: file being opened
  37  *
  38  */
  39
  40 int v9fs_file_open(struct inode *inode, struct file *file)
  41 {
  42         int err;
  43         struct v9fs_session_info *v9ses;
  44         struct p9_fid *fid;
  45         int omode;
  46
  47         p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, file);
  48         v9ses = v9fs_inode2v9ses(inode);
  49         if (v9fs_proto_dotl(v9ses))
  50                 omode = v9fs_open_to_dotl_flags(file->f_flags);
  51         else
  52                 omode = v9fs_uflags2omode(file->f_flags,
  53                                         v9fs_proto_dotu(v9ses));
  54         fid = file->private_data;
  55         if (!fid) {
  56                 fid = v9fs_fid_clone(file_dentry(file));
  57                 if (IS_ERR(fid))
  58                         return PTR_ERR(fid);
  59
  60                 if ((v9ses->cache & CACHE_WRITEBACK) && (omode & P9_OWRITE)) {
  61                         int writeback_omode = (omode & ~P9_OWRITE) | P9_ORDWR;
  62
  63                         p9_debug(P9_DEBUG_CACHE, "write-only file with writeback enabled, try opening O_RDWR\n");
  64                         err = p9_client_open(fid, writeback_omode);
  65                         if (err < 0) {
  66                                 p9_debug(P9_DEBUG_CACHE, "could not open O_RDWR, disabling caches\n");
  67                                 err = p9_client_open(fid, omode);
  68                                 fid->mode |= P9L_DIRECT;
  69                         }
  70                 } else {
  71                         err = p9_client_open(fid, omode);
  72                 }
  73                 if (err < 0) {
  74                         p9_fid_put(fid);
  75                         return err;
  76                 }
  77                 if ((file->f_flags & O_APPEND) &&
  78                         (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)))
  79                         generic_file_llseek(file, 0, SEEK_END);
  80
  81                 file->private_data = fid;
  82         }
  83
  84 #ifdef CONFIG_9P_FSCACHE
  85         if (v9ses->cache & CACHE_FSCACHE)
  86                 fscache_use_cookie(v9fs_inode_cookie(V9FS_I(inode)),
  87                                    file->f_mode & FMODE_WRITE);
  88 #endif
  89         v9fs_fid_add_modes(fid, v9ses->flags, v9ses->cache, file->f_flags);
  90         v9fs_open_fid_add(inode, &fid);
  91         return 0;
  92 }
  93
  94 /**
  95  * v9fs_file_lock - lock a file (or directory)
  96  * @filp: file to be locked
  97  * @cmd: lock command
  98  * @fl: file lock structure
  99  *
 100  * Bugs: this looks like a local only lock, we should extend into 9P
 101  *       by using open exclusive
 102  */
 103
 104 static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 105 {
 106         struct inode *inode = file_inode(filp);
 107
 108         p9_debug(P9_DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
 109
 110         if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->c.flc_type != F_UNLCK) {
 111                 filemap_write_and_wait(inode->i_mapping);
 112                 invalidate_mapping_pages(&inode->i_data, 0, -1);
 113         }
 114
 115         return 0;
 116 }
 117
 118 static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 119 {
 120         struct p9_flock flock;
 121         struct p9_fid *fid;
 122         uint8_t status = P9_LOCK_ERROR;
 123         int res = 0;
 124         struct v9fs_session_info *v9ses;
 125
 126         fid = filp->private_data;
 127         BUG_ON(fid == NULL);
 128
 129         BUG_ON((fl->c.flc_flags & FL_POSIX) != FL_POSIX);
 130
 131         res = locks_lock_file_wait(filp, fl);
 132         if (res < 0)
 133                 goto out;
 134
 135         /* convert posix lock to p9 tlock args */
 136         memset(&flock, 0, sizeof(flock));
 137         /* map the lock type */
 138         switch (fl->c.flc_type) {
 139         case F_RDLCK:
 140                 flock.type = P9_LOCK_TYPE_RDLCK;
 141                 break;
 142         case F_WRLCK:
 143                 flock.type = P9_LOCK_TYPE_WRLCK;
 144                 break;
 145         case F_UNLCK:
 146                 flock.type = P9_LOCK_TYPE_UNLCK;
 147                 break;
 148         }
 149         flock.start = fl->fl_start;
 150         if (fl->fl_end == OFFSET_MAX)
 151                 flock.length = 0;
 152         else
 153                 flock.length = fl->fl_end - fl->fl_start + 1;
 154         flock.proc_id = fl->c.flc_pid;
 155         flock.client_id = fid->clnt->name;
 156         if (IS_SETLKW(cmd))
 157                 flock.flags = P9_LOCK_FLAGS_BLOCK;
 158
 159         v9ses = v9fs_inode2v9ses(file_inode(filp));
 160
 161         /*
 162          * if its a blocked request and we get P9_LOCK_BLOCKED as the status
 163          * for lock request, keep on trying
 164          */
 165         for (;;) {
 166                 res = p9_client_lock_dotl(fid, &flock, &status);
 167                 if (res < 0)
 168                         goto out_unlock;
 169
 170                 if (status != P9_LOCK_BLOCKED)
 171                         break;
 172                 if (status == P9_LOCK_BLOCKED && !IS_SETLKW(cmd))
 173                         break;
 174                 if (schedule_timeout_interruptible(v9ses->session_lock_timeout)
 175                                 != 0)
 176                         break;
 177                 /*
 178                  * p9_client_lock_dotl overwrites flock.client_id with the
 179                  * server message, free and reuse the client name
 180                  */
 181                 if (flock.client_id != fid->clnt->name) {
 182                         kfree(flock.client_id);
 183                         flock.client_id = fid->clnt->name;
 184                 }
 185         }
 186
 187         /* map 9p status to VFS status */
 188         switch (status) {
 189         case P9_LOCK_SUCCESS:
 190                 res = 0;
 191                 break;
 192         case P9_LOCK_BLOCKED:
 193                 res = -EAGAIN;
 194                 break;
 195         default:
 196                 WARN_ONCE(1, "unknown lock status code: %d\n", status);
 197                 fallthrough;
 198         case P9_LOCK_ERROR:
 199         case P9_LOCK_GRACE:
 200                 res = -ENOLCK;
 201                 break;
 202         }
 203
 204 out_unlock:
 205         /*
 206          * incase server returned error for lock request, revert
 207          * it locally
 208          */
 209         if (res < 0 && fl->c.flc_type != F_UNLCK) {
 210                 unsigned char type = fl->c.flc_type;
 211
 212                 fl->c.flc_type = F_UNLCK;
 213                 /* Even if this fails we want to return the remote error */
 214                 locks_lock_file_wait(filp, fl);
 215                 fl->c.flc_type = type;
 216         }
 217         if (flock.client_id != fid->clnt->name)
 218                 kfree(flock.client_id);
 219 out:
 220         return res;
 221 }
 222
 223 static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
 224 {
 225         struct p9_getlock glock;
 226         struct p9_fid *fid;
 227         int res = 0;
 228
 229         fid = filp->private_data;
 230         BUG_ON(fid == NULL);
 231
 232         posix_test_lock(filp, fl);
 233         /*
 234          * if we have a conflicting lock locally, no need to validate
 235          * with server
 236          */
 237         if (fl->c.flc_type != F_UNLCK)
 238                 return res;
 239
 240         /* convert posix lock to p9 tgetlock args */
 241         memset(&glock, 0, sizeof(glock));
 242         glock.type  = P9_LOCK_TYPE_UNLCK;
 243         glock.start = fl->fl_start;
 244         if (fl->fl_end == OFFSET_MAX)
 245                 glock.length = 0;
 246         else
 247                 glock.length = fl->fl_end - fl->fl_start + 1;
 248         glock.proc_id = fl->c.flc_pid;
 249         glock.client_id = fid->clnt->name;
 250
 251         res = p9_client_getlock_dotl(fid, &glock);
 252         if (res < 0)
 253                 goto out;
 254         /* map 9p lock type to os lock type */
 255         switch (glock.type) {
 256         case P9_LOCK_TYPE_RDLCK:
 257                 fl->c.flc_type = F_RDLCK;
 258                 break;
 259         case P9_LOCK_TYPE_WRLCK:
 260                 fl->c.flc_type = F_WRLCK;
 261                 break;
 262         case P9_LOCK_TYPE_UNLCK:
 263                 fl->c.flc_type = F_UNLCK;
 264                 break;
 265         }
 266         if (glock.type != P9_LOCK_TYPE_UNLCK) {
 267                 fl->fl_start = glock.start;
 268                 if (glock.length == 0)
 269                         fl->fl_end = OFFSET_MAX;
 270                 else
 271                         fl->fl_end = glock.start + glock.length - 1;
 272                 fl->c.flc_pid = -glock.proc_id;
 273         }
 274 out:
 275         if (glock.client_id != fid->clnt->name)
 276                 kfree(glock.client_id);
 277         return res;
 278 }
 279
 280 /**
 281  * v9fs_file_lock_dotl - lock a file (or directory)
 282  * @filp: file to be locked
 283  * @cmd: lock command
 284  * @fl: file lock structure
 285  *
 286  */
 287
 288 static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
 289 {
 290         struct inode *inode = file_inode(filp);
 291         int ret = -ENOLCK;
 292
 293         p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %pD\n",
 294                  filp, cmd, fl, filp);
 295
 296         if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->c.flc_type != F_UNLCK) {
 297                 filemap_write_and_wait(inode->i_mapping);
 298                 invalidate_mapping_pages(&inode->i_data, 0, -1);
 299         }
 300
 301         if (IS_SETLK(cmd) || IS_SETLKW(cmd))
 302                 ret = v9fs_file_do_lock(filp, cmd, fl);
 303         else if (IS_GETLK(cmd))
 304                 ret = v9fs_file_getlock(filp, fl);
 305         else
 306                 ret = -EINVAL;
 307         return ret;
 308 }
 309
 310 /**
 311  * v9fs_file_flock_dotl - lock a file
 312  * @filp: file to be locked
 313  * @cmd: lock command
 314  * @fl: file lock structure
 315  *
 316  */
 317
 318 static int v9fs_file_flock_dotl(struct file *filp, int cmd,
 319         struct file_lock *fl)
 320 {
 321         struct inode *inode = file_inode(filp);
 322         int ret = -ENOLCK;
 323
 324         p9_debug(P9_DEBUG_VFS, "filp: %p cmd:%d lock: %p name: %pD\n",
 325                  filp, cmd, fl, filp);
 326
 327         if (!(fl->c.flc_flags & FL_FLOCK))
 328                 goto out_err;
 329
 330         if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->c.flc_type != F_UNLCK) {
 331                 filemap_write_and_wait(inode->i_mapping);
 332                 invalidate_mapping_pages(&inode->i_data, 0, -1);
 333         }
 334         /* Convert flock to posix lock */
 335         fl->c.flc_flags |= FL_POSIX;
 336         fl->c.flc_flags ^= FL_FLOCK;
 337
 338         if (IS_SETLK(cmd) | IS_SETLKW(cmd))
 339                 ret = v9fs_file_do_lock(filp, cmd, fl);
 340         else
 341                 ret = -EINVAL;
 342 out_err:
 343         return ret;
 344 }
 345
 346 /**
 347  * v9fs_file_read_iter - read from a file
 348  * @iocb: The operation parameters
 349  * @to: The buffer to read into
 350  *
 351  */
 352 static ssize_t
 353 v9fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 354 {
 355         struct p9_fid *fid = iocb->ki_filp->private_data;
 356
 357         p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
 358                  fid->fid, iov_iter_count(to), iocb->ki_pos);
 359
 360         if (fid->mode & P9L_DIRECT)
 361                 return netfs_unbuffered_read_iter(iocb, to);
 362
 363         p9_debug(P9_DEBUG_VFS, "(cached)\n");
 364         return netfs_file_read_iter(iocb, to);
 365 }
 366
 367 /*
 368  * v9fs_file_splice_read - splice-read from a file
 369  * @in: The 9p file to read from
 370  * @ppos: Where to find/update the file position
 371  * @pipe: The pipe to splice into
 372  * @len: The maximum amount of data to splice
 373  * @flags: SPLICE_F_* flags
 374  */
 375 static ssize_t v9fs_file_splice_read(struct file *in, loff_t *ppos,
 376                                      struct pipe_inode_info *pipe,
 377                                      size_t len, unsigned int flags)
 378 {
 379         struct p9_fid *fid = in->private_data;
 380
 381         p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
 382                  fid->fid, len, *ppos);
 383
 384         if (fid->mode & P9L_DIRECT)
 385                 return copy_splice_read(in, ppos, pipe, len, flags);
 386         return filemap_splice_read(in, ppos, pipe, len, flags);
 387 }
 388
 389 /**
 390  * v9fs_file_write_iter - write to a file
 391  * @iocb: The operation parameters
 392  * @from: The data to write
 393  *
 394  */
 395 static ssize_t
 396 v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 397 {
 398         struct file *file = iocb->ki_filp;
 399         struct p9_fid *fid = file->private_data;
 400
 401         p9_debug(P9_DEBUG_VFS, "fid %d\n", fid->fid);
 402
 403         if (fid->mode & (P9L_DIRECT | P9L_NOWRITECACHE))
 404                 return netfs_unbuffered_write_iter(iocb, from);
 405
 406         p9_debug(P9_DEBUG_CACHE, "(cached)\n");
 407         return netfs_file_write_iter(iocb, from);
 408 }
 409
 410 static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
 411                            int datasync)
 412 {
 413         struct p9_fid *fid;
 414         struct inode *inode = filp->f_mapping->host;
 415         struct p9_wstat wstat;
 416         int retval;
 417
 418         retval = file_write_and_wait_range(filp, start, end);
 419         if (retval)
 420                 return retval;
 421
 422         inode_lock(inode);
 423         p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
 424
 425         fid = filp->private_data;
 426         v9fs_blank_wstat(&wstat);
 427
 428         retval = p9_client_wstat(fid, &wstat);
 429         inode_unlock(inode);
 430
 431         return retval;
 432 }
 433
 434 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
 435                          int datasync)
 436 {
 437         struct p9_fid *fid;
 438         struct inode *inode = filp->f_mapping->host;
 439         int retval;
 440
 441         retval = file_write_and_wait_range(filp, start, end);
 442         if (retval)
 443                 return retval;
 444
 445         inode_lock(inode);
 446         p9_debug(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
 447
 448         fid = filp->private_data;
 449
 450         retval = p9_client_fsync(fid, datasync);
 451         inode_unlock(inode);
 452
 453         return retval;
 454 }
 455
 456 static int
 457 v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 458 {
 459         int retval;
 460         struct inode *inode = file_inode(filp);
 461         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
 462
 463         p9_debug(P9_DEBUG_MMAP, "filp :%p\n", filp);
 464
 465         if (!(v9ses->cache & CACHE_WRITEBACK)) {
 466                 p9_debug(P9_DEBUG_CACHE, "(read-only mmap mode)");
 467                 return generic_file_readonly_mmap(filp, vma);
 468         }
 469
 470         retval = generic_file_mmap(filp, vma);
 471         if (!retval)
 472                 vma->vm_ops = &v9fs_mmap_file_vm_ops;
 473
 474         return retval;
 475 }
 476
 477 static vm_fault_t
 478 v9fs_vm_page_mkwrite(struct vm_fault *vmf)
 479 {
 480         return netfs_page_mkwrite(vmf, NULL);
 481 }
 482
 483 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
 484 {
 485         struct inode *inode;
 486
 487         struct writeback_control wbc = {
 488                 .nr_to_write = LONG_MAX,
 489                 .sync_mode = WB_SYNC_ALL,
 490                 .range_start = (loff_t)vma->vm_pgoff * PAGE_SIZE,
 491                  /* absolute end, byte at end included */
 492                 .range_end = (loff_t)vma->vm_pgoff * PAGE_SIZE +
 493                         (vma->vm_end - vma->vm_start - 1),
 494         };
 495
 496         if (!(vma->vm_flags & VM_SHARED))
 497                 return;
 498
 499         p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma);
 500
 501         inode = file_inode(vma->vm_file);
 502         filemap_fdatawrite_wbc(inode->i_mapping, &wbc);
 503 }
 504
 505 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
 506         .close = v9fs_mmap_vm_close,
 507         .fault = filemap_fault,
 508         .map_pages = filemap_map_pages,
 509         .page_mkwrite = v9fs_vm_page_mkwrite,
 510 };
 511
 512 const struct file_operations v9fs_file_operations = {
 513         .llseek = generic_file_llseek,
 514         .read_iter = v9fs_file_read_iter,
 515         .write_iter = v9fs_file_write_iter,
 516         .open = v9fs_file_open,
 517         .release = v9fs_dir_release,
 518         .lock = v9fs_file_lock,
 519         .mmap = generic_file_readonly_mmap,
 520         .splice_read = v9fs_file_splice_read,
 521         .splice_write = iter_file_splice_write,
 522         .fsync = v9fs_file_fsync,
 523 };
 524
 525 const struct file_operations v9fs_file_operations_dotl = {
 526         .llseek = generic_file_llseek,
 527         .read_iter = v9fs_file_read_iter,
 528         .write_iter = v9fs_file_write_iter,
 529         .open = v9fs_file_open,
 530         .release = v9fs_dir_release,
 531         .lock = v9fs_file_lock_dotl,
 532         .flock = v9fs_file_flock_dotl,
 533         .mmap = v9fs_file_mmap,
 534         .splice_read = v9fs_file_splice_read,
 535         .splice_write = iter_file_splice_write,
 536         .fsync = v9fs_file_fsync_dotl,
 537 };