fs/aufs/file.c

   1 /*
   2  * Copyright (C) 2005-2017 Junjiro R. Okajima
   3  *
   4  * This program, aufs is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * handling file/dir, and address_space operation
  20  */
  21
  22 #ifdef CONFIG_AUFS_DEBUG
  23 #include <linux/migrate.h>
  24 #endif
  25 #include <linux/pagemap.h>
  26 #include "aufs.h"
  27
  28 /* drop flags for writing */
  29 unsigned int au_file_roflags(unsigned int flags)
  30 {
  31         flags &= ~(O_WRONLY | O_RDWR | O_APPEND | O_CREAT | O_TRUNC);
  32         flags |= O_RDONLY | O_NOATIME;
  33         return flags;
  34 }
  35
  36 /* common functions to regular file and dir */
  37 struct file *au_h_open(struct dentry *dentry, aufs_bindex_t bindex, int flags,
  38                        struct file *file, int force_wr)
  39 {
  40         struct file *h_file;
  41         struct dentry *h_dentry;
  42         struct inode *h_inode;
  43         struct super_block *sb;
  44         struct au_branch *br;
  45         struct path h_path;
  46         int err;
  47
  48         /* a race condition can happen between open and unlink/rmdir */
  49         h_file = ERR_PTR(-ENOENT);
  50         h_dentry = au_h_dptr(dentry, bindex);
  51         if (au_test_nfsd() && (!h_dentry || d_is_negative(h_dentry)))
  52                 goto out;
  53         h_inode = d_inode(h_dentry);
  54         spin_lock(&h_dentry->d_lock);
  55         err = (!d_unhashed(dentry) && d_unlinked(h_dentry))
  56                 /* || !d_inode(dentry)->i_nlink */
  57                 ;
  58         spin_unlock(&h_dentry->d_lock);
  59         if (unlikely(err))
  60                 goto out;
  61
  62         sb = dentry->d_sb;
  63         br = au_sbr(sb, bindex);
  64         err = au_br_test_oflag(flags, br);
  65         h_file = ERR_PTR(err);
  66         if (unlikely(err))
  67                 goto out;
  68
  69         /* drop flags for writing */
  70         if (au_test_ro(sb, bindex, d_inode(dentry))) {
  71                 if (force_wr && !(flags & O_WRONLY))
  72                         force_wr = 0;
  73                 flags = au_file_roflags(flags);
  74                 if (force_wr) {
  75                         h_file = ERR_PTR(-EROFS);
  76                         flags = au_file_roflags(flags);
  77                         if (unlikely(vfsub_native_ro(h_inode)
  78                                      || IS_APPEND(h_inode)))
  79                                 goto out;
  80                         flags &= ~O_ACCMODE;
  81                         flags |= O_WRONLY;
  82                 }
  83         }
  84         flags &= ~O_CREAT;
  85         au_br_get(br);
  86         h_path.dentry = h_dentry;
  87         h_path.mnt = au_br_mnt(br);
  88         h_file = vfsub_dentry_open(&h_path, flags);
  89         if (IS_ERR(h_file))
  90                 goto out_br;
  91
  92         if (flags & __FMODE_EXEC) {
  93                 err = deny_write_access(h_file);
  94                 if (unlikely(err)) {
  95                         fput(h_file);
  96                         h_file = ERR_PTR(err);
  97                         goto out_br;
  98                 }
  99         }
 100         fsnotify_open(h_file);
 101         goto out; /* success */
 102
 103 out_br:
 104         au_br_put(br);
 105 out:
 106         return h_file;
 107 }
 108
 109 static int au_cmoo(struct dentry *dentry)
 110 {
 111         int err, cmoo;
 112         unsigned int udba;
 113         struct path h_path;
 114         struct au_pin pin;
 115         struct au_cp_generic cpg = {
 116                 .dentry = dentry,
 117                 .bdst   = -1,
 118                 .bsrc   = -1,
 119                 .len    = -1,
 120                 .pin    = &pin,
 121                 .flags  = AuCpup_DTIME | AuCpup_HOPEN
 122         };
 123         struct inode *delegated;
 124         struct super_block *sb;
 125         struct au_sbinfo *sbinfo;
 126         struct au_fhsm *fhsm;
 127         pid_t pid;
 128         struct au_branch *br;
 129         struct dentry *parent;
 130         struct au_hinode *hdir;
 131
 132         DiMustWriteLock(dentry);
 133         IiMustWriteLock(d_inode(dentry));
 134
 135         err = 0;
 136         if (IS_ROOT(dentry))
 137                 goto out;
 138         cpg.bsrc = au_dbtop(dentry);
 139         if (!cpg.bsrc)
 140                 goto out;
 141
 142         sb = dentry->d_sb;
 143         sbinfo = au_sbi(sb);
 144         fhsm = &sbinfo->si_fhsm;
 145         pid = au_fhsm_pid(fhsm);
 146         if (pid
 147             && (current->pid == pid
 148                 || current->real_parent->pid == pid))
 149                 goto out;
 150
 151         br = au_sbr(sb, cpg.bsrc);
 152         cmoo = au_br_cmoo(br->br_perm);
 153         if (!cmoo)
 154                 goto out;
 155         if (!d_is_reg(dentry))
 156                 cmoo &= AuBrAttr_COO_ALL;
 157         if (!cmoo)
 158                 goto out;
 159
 160         parent = dget_parent(dentry);
 161         di_write_lock_parent(parent);
 162         err = au_wbr_do_copyup_bu(dentry, cpg.bsrc - 1);
 163         cpg.bdst = err;
 164         if (unlikely(err < 0)) {
 165                 err = 0;        /* there is no upper writable branch */
 166                 goto out_dgrade;
 167         }
 168         AuDbg("bsrc %d, bdst %d\n", cpg.bsrc, cpg.bdst);
 169
 170         /* do not respect the coo attrib for the target branch */
 171         err = au_cpup_dirs(dentry, cpg.bdst);
 172         if (unlikely(err))
 173                 goto out_dgrade;
 174
 175         di_downgrade_lock(parent, AuLock_IR);
 176         udba = au_opt_udba(sb);
 177         err = au_pin(&pin, dentry, cpg.bdst, udba,
 178                      AuPin_DI_LOCKED | AuPin_MNT_WRITE);
 179         if (unlikely(err))
 180                 goto out_parent;
 181
 182         err = au_sio_cpup_simple(&cpg);
 183         au_unpin(&pin);
 184         if (unlikely(err))
 185                 goto out_parent;
 186         if (!(cmoo & AuBrWAttr_MOO))
 187                 goto out_parent; /* success */
 188
 189         err = au_pin(&pin, dentry, cpg.bsrc, udba,
 190                      AuPin_DI_LOCKED | AuPin_MNT_WRITE);
 191         if (unlikely(err))
 192                 goto out_parent;
 193
 194         h_path.mnt = au_br_mnt(br);
 195         h_path.dentry = au_h_dptr(dentry, cpg.bsrc);
 196         hdir = au_hi(d_inode(parent), cpg.bsrc);
 197         delegated = NULL;
 198         err = vfsub_unlink(hdir->hi_inode, &h_path, &delegated, /*force*/1);
 199         au_unpin(&pin);
 200         /* todo: keep h_dentry or not? */
 201         if (unlikely(err == -EWOULDBLOCK)) {
 202                 pr_warn("cannot retry for NFSv4 delegation"
 203                         " for an internal unlink\n");
 204                 iput(delegated);
 205         }
 206         if (unlikely(err)) {
 207                 pr_err("unlink %pd after coo failed (%d), ignored\n",
 208                        dentry, err);
 209                 err = 0;
 210         }
 211         goto out_parent; /* success */
 212
 213 out_dgrade:
 214         di_downgrade_lock(parent, AuLock_IR);
 215 out_parent:
 216         di_read_unlock(parent, AuLock_IR);
 217         dput(parent);
 218 out:
 219         AuTraceErr(err);
 220         return err;
 221 }
 222
 223 int au_do_open(struct file *file, struct au_do_open_args *args)
 224 {
 225         int err, no_lock = args->no_lock;
 226         struct dentry *dentry;
 227         struct au_finfo *finfo;
 228
 229         if (!no_lock)
 230                 err = au_finfo_init(file, args->fidir);
 231         else {
 232                 lockdep_off();
 233                 err = au_finfo_init(file, args->fidir);
 234                 lockdep_on();
 235         }
 236         if (unlikely(err))
 237                 goto out;
 238
 239         dentry = file->f_path.dentry;
 240         AuDebugOn(IS_ERR_OR_NULL(dentry));
 241         if (!no_lock) {
 242                 di_write_lock_child(dentry);
 243                 err = au_cmoo(dentry);
 244                 di_downgrade_lock(dentry, AuLock_IR);
 245                 if (!err)
 246                         err = args->open(file, vfsub_file_flags(file), NULL);
 247                 di_read_unlock(dentry, AuLock_IR);
 248         } else {
 249                 err = au_cmoo(dentry);
 250                 if (!err)
 251                         err = args->open(file, vfsub_file_flags(file),
 252                                          args->h_file);
 253                 if (!err && au_fbtop(file) != au_dbtop(dentry))
 254                         /*
 255                          * cmoo happens after h_file was opened.
 256                          * need to refresh file later.
 257                          */
 258                         atomic_dec(&au_fi(file)->fi_generation);
 259         }
 260
 261         finfo = au_fi(file);
 262         if (!err) {
 263                 finfo->fi_file = file;
 264                 au_sphl_add(&finfo->fi_hlist,
 265                             &au_sbi(file->f_path.dentry->d_sb)->si_files);
 266         }
 267         if (!no_lock)
 268                 fi_write_unlock(file);
 269         else {
 270                 lockdep_off();
 271                 fi_write_unlock(file);
 272                 lockdep_on();
 273         }
 274         if (unlikely(err)) {
 275                 finfo->fi_hdir = NULL;
 276                 au_finfo_fin(file);
 277         }
 278
 279 out:
 280         return err;
 281 }
 282
 283 int au_reopen_nondir(struct file *file)
 284 {
 285         int err;
 286         aufs_bindex_t btop;
 287         struct dentry *dentry;
 288         struct file *h_file, *h_file_tmp;
 289
 290         dentry = file->f_path.dentry;
 291         btop = au_dbtop(dentry);
 292         h_file_tmp = NULL;
 293         if (au_fbtop(file) == btop) {
 294                 h_file = au_hf_top(file);
 295                 if (file->f_mode == h_file->f_mode)
 296                         return 0; /* success */
 297                 h_file_tmp = h_file;
 298                 get_file(h_file_tmp);
 299                 au_set_h_fptr(file, btop, NULL);
 300         }
 301         AuDebugOn(au_fi(file)->fi_hdir);
 302         /*
 303          * it can happen
 304          * file exists on both of rw and ro
 305          * open --> dbtop and fbtop are both 0
 306          * prepend a branch as rw, "rw" become ro
 307          * remove rw/file
 308          * delete the top branch, "rw" becomes rw again
 309          *      --> dbtop is 1, fbtop is still 0
 310          * write --> fbtop is 0 but dbtop is 1
 311          */
 312         /* AuDebugOn(au_fbtop(file) < btop); */
 313
 314         h_file = au_h_open(dentry, btop, vfsub_file_flags(file) & ~O_TRUNC,
 315                            file, /*force_wr*/0);
 316         err = PTR_ERR(h_file);
 317         if (IS_ERR(h_file)) {
 318                 if (h_file_tmp) {
 319                         au_sbr_get(dentry->d_sb, btop);
 320                         au_set_h_fptr(file, btop, h_file_tmp);
 321                         h_file_tmp = NULL;
 322                 }
 323                 goto out; /* todo: close all? */
 324         }
 325
 326         err = 0;
 327         au_set_fbtop(file, btop);
 328         au_set_h_fptr(file, btop, h_file);
 329         au_update_figen(file);
 330         /* todo: necessary? */
 331         /* file->f_ra = h_file->f_ra; */
 332
 333 out:
 334         if (h_file_tmp)
 335                 fput(h_file_tmp);
 336         return err;
 337 }
 338
 339 /* ---------------------------------------------------------------------- */
 340
 341 static int au_reopen_wh(struct file *file, aufs_bindex_t btgt,
 342                         struct dentry *hi_wh)
 343 {
 344         int err;
 345         aufs_bindex_t btop;
 346         struct au_dinfo *dinfo;
 347         struct dentry *h_dentry;
 348         struct au_hdentry *hdp;
 349
 350         dinfo = au_di(file->f_path.dentry);
 351         AuRwMustWriteLock(&dinfo->di_rwsem);
 352
 353         btop = dinfo->di_btop;
 354         dinfo->di_btop = btgt;
 355         hdp = au_hdentry(dinfo, btgt);
 356         h_dentry = hdp->hd_dentry;
 357         hdp->hd_dentry = hi_wh;
 358         err = au_reopen_nondir(file);
 359         hdp->hd_dentry = h_dentry;
 360         dinfo->di_btop = btop;
 361
 362         return err;
 363 }
 364
 365 static int au_ready_to_write_wh(struct file *file, loff_t len,
 366                                 aufs_bindex_t bcpup, struct au_pin *pin)
 367 {
 368         int err;
 369         struct inode *inode, *h_inode;
 370         struct dentry *h_dentry, *hi_wh;
 371         struct au_cp_generic cpg = {
 372                 .dentry = file->f_path.dentry,
 373                 .bdst   = bcpup,
 374                 .bsrc   = -1,
 375                 .len    = len,
 376                 .pin    = pin
 377         };
 378
 379         au_update_dbtop(cpg.dentry);
 380         inode = d_inode(cpg.dentry);
 381         h_inode = NULL;
 382         if (au_dbtop(cpg.dentry) <= bcpup
 383             && au_dbbot(cpg.dentry) >= bcpup) {
 384                 h_dentry = au_h_dptr(cpg.dentry, bcpup);
 385                 if (h_dentry && d_is_positive(h_dentry))
 386                         h_inode = d_inode(h_dentry);
 387         }
 388         hi_wh = au_hi_wh(inode, bcpup);
 389         if (!hi_wh && !h_inode)
 390                 err = au_sio_cpup_wh(&cpg, file);
 391         else
 392                 /* already copied-up after unlink */
 393                 err = au_reopen_wh(file, bcpup, hi_wh);
 394
 395         if (!err
 396             && (inode->i_nlink > 1
 397                 || (inode->i_state & I_LINKABLE))
 398             && au_opt_test(au_mntflags(cpg.dentry->d_sb), PLINK))
 399                 au_plink_append(inode, bcpup, au_h_dptr(cpg.dentry, bcpup));
 400
 401         return err;
 402 }
 403
 404 /*
 405  * prepare the @file for writing.
 406  */
 407 int au_ready_to_write(struct file *file, loff_t len, struct au_pin *pin)
 408 {
 409         int err;
 410         aufs_bindex_t dbtop;
 411         struct dentry *parent;
 412         struct inode *inode;
 413         struct super_block *sb;
 414         struct file *h_file;
 415         struct au_cp_generic cpg = {
 416                 .dentry = file->f_path.dentry,
 417                 .bdst   = -1,
 418                 .bsrc   = -1,
 419                 .len    = len,
 420                 .pin    = pin,
 421                 .flags  = AuCpup_DTIME
 422         };
 423
 424         sb = cpg.dentry->d_sb;
 425         inode = d_inode(cpg.dentry);
 426         cpg.bsrc = au_fbtop(file);
 427         err = au_test_ro(sb, cpg.bsrc, inode);
 428         if (!err && (au_hf_top(file)->f_mode & FMODE_WRITE)) {
 429                 err = au_pin(pin, cpg.dentry, cpg.bsrc, AuOpt_UDBA_NONE,
 430                              /*flags*/0);
 431                 goto out;
 432         }
 433
 434         /* need to cpup or reopen */
 435         parent = dget_parent(cpg.dentry);
 436         di_write_lock_parent(parent);
 437         err = AuWbrCopyup(au_sbi(sb), cpg.dentry);
 438         cpg.bdst = err;
 439         if (unlikely(err < 0))
 440                 goto out_dgrade;
 441         err = 0;
 442
 443         if (!d_unhashed(cpg.dentry) && !au_h_dptr(parent, cpg.bdst)) {
 444                 err = au_cpup_dirs(cpg.dentry, cpg.bdst);
 445                 if (unlikely(err))
 446                         goto out_dgrade;
 447         }
 448
 449         err = au_pin(pin, cpg.dentry, cpg.bdst, AuOpt_UDBA_NONE,
 450                      AuPin_DI_LOCKED | AuPin_MNT_WRITE);
 451         if (unlikely(err))
 452                 goto out_dgrade;
 453
 454         dbtop = au_dbtop(cpg.dentry);
 455         if (dbtop <= cpg.bdst)
 456                 cpg.bsrc = cpg.bdst;
 457
 458         if (dbtop <= cpg.bdst           /* just reopen */
 459             || !d_unhashed(cpg.dentry)  /* copyup and reopen */
 460                 ) {
 461                 h_file = au_h_open_pre(cpg.dentry, cpg.bsrc, /*force_wr*/0);
 462                 if (IS_ERR(h_file))
 463                         err = PTR_ERR(h_file);
 464                 else {
 465                         di_downgrade_lock(parent, AuLock_IR);
 466                         if (dbtop > cpg.bdst)
 467                                 err = au_sio_cpup_simple(&cpg);
 468                         if (!err)
 469                                 err = au_reopen_nondir(file);
 470                         au_h_open_post(cpg.dentry, cpg.bsrc, h_file);
 471                 }
 472         } else {                        /* copyup as wh and reopen */
 473                 /*
 474                  * since writable hfsplus branch is not supported,
 475                  * h_open_pre/post() are unnecessary.
 476                  */
 477                 err = au_ready_to_write_wh(file, len, cpg.bdst, pin);
 478                 di_downgrade_lock(parent, AuLock_IR);
 479         }
 480
 481         if (!err) {
 482                 au_pin_set_parent_lflag(pin, /*lflag*/0);
 483                 goto out_dput; /* success */
 484         }
 485         au_unpin(pin);
 486         goto out_unlock;
 487
 488 out_dgrade:
 489         di_downgrade_lock(parent, AuLock_IR);
 490 out_unlock:
 491         di_read_unlock(parent, AuLock_IR);
 492 out_dput:
 493         dput(parent);
 494 out:
 495         return err;
 496 }
 497
 498 /* ---------------------------------------------------------------------- */
 499
 500 int au_do_flush(struct file *file, fl_owner_t id,
 501                 int (*flush)(struct file *file, fl_owner_t id))
 502 {
 503         int err;
 504         struct super_block *sb;
 505         struct inode *inode;
 506
 507         inode = file_inode(file);
 508         sb = inode->i_sb;
 509         si_noflush_read_lock(sb);
 510         fi_read_lock(file);
 511         ii_read_lock_child(inode);
 512
 513         err = flush(file, id);
 514         au_cpup_attr_timesizes(inode);
 515
 516         ii_read_unlock(inode);
 517         fi_read_unlock(file);
 518         si_read_unlock(sb);
 519         return err;
 520 }
 521
 522 /* ---------------------------------------------------------------------- */
 523
 524 static int au_file_refresh_by_inode(struct file *file, int *need_reopen)
 525 {
 526         int err;
 527         struct au_pin pin;
 528         struct au_finfo *finfo;
 529         struct dentry *parent, *hi_wh;
 530         struct inode *inode;
 531         struct super_block *sb;
 532         struct au_cp_generic cpg = {
 533                 .dentry = file->f_path.dentry,
 534                 .bdst   = -1,
 535                 .bsrc   = -1,
 536                 .len    = -1,
 537                 .pin    = &pin,
 538                 .flags  = AuCpup_DTIME
 539         };
 540
 541         FiMustWriteLock(file);
 542
 543         err = 0;
 544         finfo = au_fi(file);
 545         sb = cpg.dentry->d_sb;
 546         inode = d_inode(cpg.dentry);
 547         cpg.bdst = au_ibtop(inode);
 548         if (cpg.bdst == finfo->fi_btop || IS_ROOT(cpg.dentry))
 549                 goto out;
 550
 551         parent = dget_parent(cpg.dentry);
 552         if (au_test_ro(sb, cpg.bdst, inode)) {
 553                 di_read_lock_parent(parent, !AuLock_IR);
 554                 err = AuWbrCopyup(au_sbi(sb), cpg.dentry);
 555                 cpg.bdst = err;
 556                 di_read_unlock(parent, !AuLock_IR);
 557                 if (unlikely(err < 0))
 558                         goto out_parent;
 559                 err = 0;
 560         }
 561
 562         di_read_lock_parent(parent, AuLock_IR);
 563         hi_wh = au_hi_wh(inode, cpg.bdst);
 564         if (!S_ISDIR(inode->i_mode)
 565             && au_opt_test(au_mntflags(sb), PLINK)
 566             && au_plink_test(inode)
 567             && !d_unhashed(cpg.dentry)
 568             && cpg.bdst < au_dbtop(cpg.dentry)) {
 569                 err = au_test_and_cpup_dirs(cpg.dentry, cpg.bdst);
 570                 if (unlikely(err))
 571                         goto out_unlock;
 572
 573                 /* always superio. */
 574                 err = au_pin(&pin, cpg.dentry, cpg.bdst, AuOpt_UDBA_NONE,
 575                              AuPin_DI_LOCKED | AuPin_MNT_WRITE);
 576                 if (!err) {
 577                         err = au_sio_cpup_simple(&cpg);
 578                         au_unpin(&pin);
 579                 }
 580         } else if (hi_wh) {
 581                 /* already copied-up after unlink */
 582                 err = au_reopen_wh(file, cpg.bdst, hi_wh);
 583                 *need_reopen = 0;
 584         }
 585
 586 out_unlock:
 587         di_read_unlock(parent, AuLock_IR);
 588 out_parent:
 589         dput(parent);
 590 out:
 591         return err;
 592 }
 593
 594 static void au_do_refresh_dir(struct file *file)
 595 {
 596         aufs_bindex_t bindex, bbot, new_bindex, brid;
 597         struct au_hfile *p, tmp, *q;
 598         struct au_finfo *finfo;
 599         struct super_block *sb;
 600         struct au_fidir *fidir;
 601
 602         FiMustWriteLock(file);
 603
 604         sb = file->f_path.dentry->d_sb;
 605         finfo = au_fi(file);
 606         fidir = finfo->fi_hdir;
 607         AuDebugOn(!fidir);
 608         p = fidir->fd_hfile + finfo->fi_btop;
 609         brid = p->hf_br->br_id;
 610         bbot = fidir->fd_bbot;
 611         for (bindex = finfo->fi_btop; bindex <= bbot; bindex++, p++) {
 612                 if (!p->hf_file)
 613                         continue;
 614
 615                 new_bindex = au_br_index(sb, p->hf_br->br_id);
 616                 if (new_bindex == bindex)
 617                         continue;
 618                 if (new_bindex < 0) {
 619                         au_set_h_fptr(file, bindex, NULL);
 620                         continue;
 621                 }
 622
 623                 /* swap two lower inode, and loop again */
 624                 q = fidir->fd_hfile + new_bindex;
 625                 tmp = *q;
 626                 *q = *p;
 627                 *p = tmp;
 628                 if (tmp.hf_file) {
 629                         bindex--;
 630                         p--;
 631                 }
 632         }
 633
 634         p = fidir->fd_hfile;
 635         if (!au_test_mmapped(file) && !d_unlinked(file->f_path.dentry)) {
 636                 bbot = au_sbbot(sb);
 637                 for (finfo->fi_btop = 0; finfo->fi_btop <= bbot;
 638                      finfo->fi_btop++, p++)
 639                         if (p->hf_file) {
 640                                 if (file_inode(p->hf_file))
 641                                         break;
 642                                 au_hfput(p, /*execed*/0);
 643                         }
 644         } else {
 645                 bbot = au_br_index(sb, brid);
 646                 for (finfo->fi_btop = 0; finfo->fi_btop < bbot;
 647                      finfo->fi_btop++, p++)
 648                         if (p->hf_file)
 649                                 au_hfput(p, /*execed*/0);
 650                 bbot = au_sbbot(sb);
 651         }
 652
 653         p = fidir->fd_hfile + bbot;
 654         for (fidir->fd_bbot = bbot; fidir->fd_bbot >= finfo->fi_btop;
 655              fidir->fd_bbot--, p--)
 656                 if (p->hf_file) {
 657                         if (file_inode(p->hf_file))
 658                                 break;
 659                         au_hfput(p, /*execed*/0);
 660                 }
 661         AuDebugOn(fidir->fd_bbot < finfo->fi_btop);
 662 }
 663
 664 /*
 665  * after branch manipulating, refresh the file.
 666  */
 667 static int refresh_file(struct file *file, int (*reopen)(struct file *file))
 668 {
 669         int err, need_reopen, nbr;
 670         aufs_bindex_t bbot, bindex;
 671         struct dentry *dentry;
 672         struct super_block *sb;
 673         struct au_finfo *finfo;
 674         struct au_hfile *hfile;
 675
 676         dentry = file->f_path.dentry;
 677         sb = dentry->d_sb;
 678         nbr = au_sbbot(sb) + 1;
 679         finfo = au_fi(file);
 680         if (!finfo->fi_hdir) {
 681                 hfile = &finfo->fi_htop;
 682                 AuDebugOn(!hfile->hf_file);
 683                 bindex = au_br_index(sb, hfile->hf_br->br_id);
 684                 AuDebugOn(bindex < 0);
 685                 if (bindex != finfo->fi_btop)
 686                         au_set_fbtop(file, bindex);
 687         } else {
 688                 err = au_fidir_realloc(finfo, nbr, /*may_shrink*/0);
 689                 if (unlikely(err))
 690                         goto out;
 691                 au_do_refresh_dir(file);
 692         }
 693
 694         err = 0;
 695         need_reopen = 1;
 696         if (!au_test_mmapped(file))
 697                 err = au_file_refresh_by_inode(file, &need_reopen);
 698         if (finfo->fi_hdir)
 699                 /* harmless if err */
 700                 au_fidir_realloc(finfo, nbr, /*may_shrink*/1);
 701         if (!err && need_reopen && !d_unlinked(dentry))
 702                 err = reopen(file);
 703         if (!err) {
 704                 au_update_figen(file);
 705                 goto out; /* success */
 706         }
 707
 708         /* error, close all lower files */
 709         if (finfo->fi_hdir) {
 710                 bbot = au_fbbot_dir(file);
 711                 for (bindex = au_fbtop(file); bindex <= bbot; bindex++)
 712                         au_set_h_fptr(file, bindex, NULL);
 713         }
 714
 715 out:
 716         return err;
 717 }
 718
 719 /* common function to regular file and dir */
 720 int au_reval_and_lock_fdi(struct file *file, int (*reopen)(struct file *file),
 721                           int wlock, unsigned int fi_lsc)
 722 {
 723         int err;
 724         unsigned int sigen, figen;
 725         aufs_bindex_t btop;
 726         unsigned char pseudo_link;
 727         struct dentry *dentry;
 728         struct inode *inode;
 729
 730         err = 0;
 731         dentry = file->f_path.dentry;
 732         inode = d_inode(dentry);
 733         sigen = au_sigen(dentry->d_sb);
 734         fi_write_lock_nested(file, fi_lsc);
 735         figen = au_figen(file);
 736         if (!fi_lsc)
 737                 di_write_lock_child(dentry);
 738         else
 739                 di_write_lock_child2(dentry);
 740         btop = au_dbtop(dentry);
 741         pseudo_link = (btop != au_ibtop(inode));
 742         if (sigen == figen && !pseudo_link && au_fbtop(file) == btop) {
 743                 if (!wlock) {
 744                         di_downgrade_lock(dentry, AuLock_IR);
 745                         fi_downgrade_lock(file);
 746                 }
 747                 goto out; /* success */
 748         }
 749
 750         AuDbg("sigen %d, figen %d\n", sigen, figen);
 751         if (au_digen_test(dentry, sigen)) {
 752                 err = au_reval_dpath(dentry, sigen);
 753                 AuDebugOn(!err && au_digen_test(dentry, sigen));
 754         }
 755
 756         if (!err)
 757                 err = refresh_file(file, reopen);
 758         if (!err) {
 759                 if (!wlock) {
 760                         di_downgrade_lock(dentry, AuLock_IR);
 761                         fi_downgrade_lock(file);
 762                 }
 763         } else {
 764                 di_write_unlock(dentry);
 765                 fi_write_unlock(file);
 766         }
 767
 768 out:
 769         return err;
 770 }
 771
 772 /* ---------------------------------------------------------------------- */
 773
 774 /* cf. aufs_nopage() */
 775 /* for madvise(2) */
 776 static int aufs_readpage(struct file *file __maybe_unused, struct page *page)
 777 {
 778         unlock_page(page);
 779         return 0;
 780 }
 781
 782 /* it will never be called, but necessary to support O_DIRECT */
 783 static ssize_t aufs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 784 { BUG(); return 0; }
 785
 786 /* they will never be called. */
 787 #ifdef CONFIG_AUFS_DEBUG
 788 static int aufs_write_begin(struct file *file, struct address_space *mapping,
 789                             loff_t pos, unsigned len, unsigned flags,
 790                             struct page **pagep, void **fsdata)
 791 { AuUnsupport(); return 0; }
 792 static int aufs_write_end(struct file *file, struct address_space *mapping,
 793                           loff_t pos, unsigned len, unsigned copied,
 794                           struct page *page, void *fsdata)
 795 { AuUnsupport(); return 0; }
 796 static int aufs_writepage(struct page *page, struct writeback_control *wbc)
 797 { AuUnsupport(); return 0; }
 798
 799 static int aufs_set_page_dirty(struct page *page)
 800 { AuUnsupport(); return 0; }
 801 static void aufs_invalidatepage(struct page *page, unsigned int offset,
 802                                 unsigned int length)
 803 { AuUnsupport(); }
 804 static int aufs_releasepage(struct page *page, gfp_t gfp)
 805 { AuUnsupport(); return 0; }
 806 #if 0 /* called by memory compaction regardless file */
 807 static int aufs_migratepage(struct address_space *mapping, struct page *newpage,
 808                             struct page *page, enum migrate_mode mode)
 809 { AuUnsupport(); return 0; }
 810 #endif
 811 static bool aufs_isolate_page(struct page *page, isolate_mode_t mode)
 812 { AuUnsupport(); return true; }
 813 static void aufs_putback_page(struct page *page)
 814 { AuUnsupport(); }
 815 static int aufs_launder_page(struct page *page)
 816 { AuUnsupport(); return 0; }
 817 static int aufs_is_partially_uptodate(struct page *page,
 818                                       unsigned long from,
 819                                       unsigned long count)
 820 { AuUnsupport(); return 0; }
 821 static void aufs_is_dirty_writeback(struct page *page, bool *dirty,
 822                                     bool *writeback)
 823 { AuUnsupport(); }
 824 static int aufs_error_remove_page(struct address_space *mapping,
 825                                   struct page *page)
 826 { AuUnsupport(); return 0; }
 827 static int aufs_swap_activate(struct swap_info_struct *sis, struct file *file,
 828                               sector_t *span)
 829 { AuUnsupport(); return 0; }
 830 static void aufs_swap_deactivate(struct file *file)
 831 { AuUnsupport(); }
 832 #endif /* CONFIG_AUFS_DEBUG */
 833
 834 const struct address_space_operations aufs_aop = {
 835         .readpage               = aufs_readpage,
 836         .direct_IO              = aufs_direct_IO,
 837 #ifdef CONFIG_AUFS_DEBUG
 838         .writepage              = aufs_writepage,
 839         /* no writepages, because of writepage */
 840         .set_page_dirty         = aufs_set_page_dirty,
 841         /* no readpages, because of readpage */
 842         .write_begin            = aufs_write_begin,
 843         .write_end              = aufs_write_end,
 844         /* no bmap, no block device */
 845         .invalidatepage         = aufs_invalidatepage,
 846         .releasepage            = aufs_releasepage,
 847         /* is fallback_migrate_page ok? */
 848         /* .migratepage         = aufs_migratepage, */
 849         .isolate_page           = aufs_isolate_page,
 850         .putback_page           = aufs_putback_page,
 851         .launder_page           = aufs_launder_page,
 852         .is_partially_uptodate  = aufs_is_partially_uptodate,
 853         .is_dirty_writeback     = aufs_is_dirty_writeback,
 854         .error_remove_page      = aufs_error_remove_page,
 855         .swap_activate          = aufs_swap_activate,
 856         .swap_deactivate        = aufs_swap_deactivate
 857 #endif /* CONFIG_AUFS_DEBUG */
 858 };