linux/fs/xfs/xfs_iget.c
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   1/*
   2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would 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, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include "xfs_fs.h"
  20#include "xfs_types.h"
  21#include "xfs_acl.h"
  22#include "xfs_log.h"
  23#include "xfs_inum.h"
  24#include "xfs_trans.h"
  25#include "xfs_sb.h"
  26#include "xfs_ag.h"
  27#include "xfs_mount.h"
  28#include "xfs_bmap_btree.h"
  29#include "xfs_alloc_btree.h"
  30#include "xfs_ialloc_btree.h"
  31#include "xfs_dinode.h"
  32#include "xfs_inode.h"
  33#include "xfs_btree.h"
  34#include "xfs_ialloc.h"
  35#include "xfs_quota.h"
  36#include "xfs_utils.h"
  37#include "xfs_trans_priv.h"
  38#include "xfs_inode_item.h"
  39#include "xfs_bmap.h"
  40#include "xfs_trace.h"
  41
  42
  43/*
  44 * Allocate and initialise an xfs_inode.
  45 */
  46STATIC struct xfs_inode *
  47xfs_inode_alloc(
  48        struct xfs_mount        *mp,
  49        xfs_ino_t               ino)
  50{
  51        struct xfs_inode        *ip;
  52
  53        /*
  54         * if this didn't occur in transactions, we could use
  55         * KM_MAYFAIL and return NULL here on ENOMEM. Set the
  56         * code up to do this anyway.
  57         */
  58        ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
  59        if (!ip)
  60                return NULL;
  61        if (inode_init_always(mp->m_super, VFS_I(ip))) {
  62                kmem_zone_free(xfs_inode_zone, ip);
  63                return NULL;
  64        }
  65
  66        ASSERT(atomic_read(&ip->i_pincount) == 0);
  67        ASSERT(!spin_is_locked(&ip->i_flags_lock));
  68        ASSERT(!xfs_isiflocked(ip));
  69        ASSERT(ip->i_ino == 0);
  70
  71        mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
  72
  73        /* initialise the xfs inode */
  74        ip->i_ino = ino;
  75        ip->i_mount = mp;
  76        memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
  77        ip->i_afp = NULL;
  78        memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
  79        ip->i_flags = 0;
  80        ip->i_delayed_blks = 0;
  81        memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));
  82
  83        return ip;
  84}
  85
  86STATIC void
  87xfs_inode_free_callback(
  88        struct rcu_head         *head)
  89{
  90        struct inode            *inode = container_of(head, struct inode, i_rcu);
  91        struct xfs_inode        *ip = XFS_I(inode);
  92
  93        kmem_zone_free(xfs_inode_zone, ip);
  94}
  95
  96void
  97xfs_inode_free(
  98        struct xfs_inode        *ip)
  99{
 100        switch (ip->i_d.di_mode & S_IFMT) {
 101        case S_IFREG:
 102        case S_IFDIR:
 103        case S_IFLNK:
 104                xfs_idestroy_fork(ip, XFS_DATA_FORK);
 105                break;
 106        }
 107
 108        if (ip->i_afp)
 109                xfs_idestroy_fork(ip, XFS_ATTR_FORK);
 110
 111        if (ip->i_itemp) {
 112                ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
 113                xfs_inode_item_destroy(ip);
 114                ip->i_itemp = NULL;
 115        }
 116
 117        /* asserts to verify all state is correct here */
 118        ASSERT(atomic_read(&ip->i_pincount) == 0);
 119        ASSERT(!spin_is_locked(&ip->i_flags_lock));
 120        ASSERT(!xfs_isiflocked(ip));
 121
 122        /*
 123         * Because we use RCU freeing we need to ensure the inode always
 124         * appears to be reclaimed with an invalid inode number when in the
 125         * free state. The ip->i_flags_lock provides the barrier against lookup
 126         * races.
 127         */
 128        spin_lock(&ip->i_flags_lock);
 129        ip->i_flags = XFS_IRECLAIM;
 130        ip->i_ino = 0;
 131        spin_unlock(&ip->i_flags_lock);
 132
 133        call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
 134}
 135
 136/*
 137 * Check the validity of the inode we just found it the cache
 138 */
 139static int
 140xfs_iget_cache_hit(
 141        struct xfs_perag        *pag,
 142        struct xfs_inode        *ip,
 143        xfs_ino_t               ino,
 144        int                     flags,
 145        int                     lock_flags) __releases(RCU)
 146{
 147        struct inode            *inode = VFS_I(ip);
 148        struct xfs_mount        *mp = ip->i_mount;
 149        int                     error;
 150
 151        /*
 152         * check for re-use of an inode within an RCU grace period due to the
 153         * radix tree nodes not being updated yet. We monitor for this by
 154         * setting the inode number to zero before freeing the inode structure.
 155         * If the inode has been reallocated and set up, then the inode number
 156         * will not match, so check for that, too.
 157         */
 158        spin_lock(&ip->i_flags_lock);
 159        if (ip->i_ino != ino) {
 160                trace_xfs_iget_skip(ip);
 161                XFS_STATS_INC(xs_ig_frecycle);
 162                error = EAGAIN;
 163                goto out_error;
 164        }
 165
 166
 167        /*
 168         * If we are racing with another cache hit that is currently
 169         * instantiating this inode or currently recycling it out of
 170         * reclaimabe state, wait for the initialisation to complete
 171         * before continuing.
 172         *
 173         * XXX(hch): eventually we should do something equivalent to
 174         *           wait_on_inode to wait for these flags to be cleared
 175         *           instead of polling for it.
 176         */
 177        if (ip->i_flags & (XFS_INEW|XFS_IRECLAIM)) {
 178                trace_xfs_iget_skip(ip);
 179                XFS_STATS_INC(xs_ig_frecycle);
 180                error = EAGAIN;
 181                goto out_error;
 182        }
 183
 184        /*
 185         * If lookup is racing with unlink return an error immediately.
 186         */
 187        if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
 188                error = ENOENT;
 189                goto out_error;
 190        }
 191
 192        /*
 193         * If IRECLAIMABLE is set, we've torn down the VFS inode already.
 194         * Need to carefully get it back into useable state.
 195         */
 196        if (ip->i_flags & XFS_IRECLAIMABLE) {
 197                trace_xfs_iget_reclaim(ip);
 198
 199                /*
 200                 * We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
 201                 * from stomping over us while we recycle the inode.  We can't
 202                 * clear the radix tree reclaimable tag yet as it requires
 203                 * pag_ici_lock to be held exclusive.
 204                 */
 205                ip->i_flags |= XFS_IRECLAIM;
 206
 207                spin_unlock(&ip->i_flags_lock);
 208                rcu_read_unlock();
 209
 210                error = -inode_init_always(mp->m_super, inode);
 211                if (error) {
 212                        /*
 213                         * Re-initializing the inode failed, and we are in deep
 214                         * trouble.  Try to re-add it to the reclaim list.
 215                         */
 216                        rcu_read_lock();
 217                        spin_lock(&ip->i_flags_lock);
 218
 219                        ip->i_flags &= ~(XFS_INEW | XFS_IRECLAIM);
 220                        ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
 221                        trace_xfs_iget_reclaim_fail(ip);
 222                        goto out_error;
 223                }
 224
 225                spin_lock(&pag->pag_ici_lock);
 226                spin_lock(&ip->i_flags_lock);
 227
 228                /*
 229                 * Clear the per-lifetime state in the inode as we are now
 230                 * effectively a new inode and need to return to the initial
 231                 * state before reuse occurs.
 232                 */
 233                ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
 234                ip->i_flags |= XFS_INEW;
 235                __xfs_inode_clear_reclaim_tag(mp, pag, ip);
 236                inode->i_state = I_NEW;
 237
 238                ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
 239                mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
 240
 241                spin_unlock(&ip->i_flags_lock);
 242                spin_unlock(&pag->pag_ici_lock);
 243        } else {
 244                /* If the VFS inode is being torn down, pause and try again. */
 245                if (!igrab(inode)) {
 246                        trace_xfs_iget_skip(ip);
 247                        error = EAGAIN;
 248                        goto out_error;
 249                }
 250
 251                /* We've got a live one. */
 252                spin_unlock(&ip->i_flags_lock);
 253                rcu_read_unlock();
 254                trace_xfs_iget_hit(ip);
 255        }
 256
 257        if (lock_flags != 0)
 258                xfs_ilock(ip, lock_flags);
 259
 260        xfs_iflags_clear(ip, XFS_ISTALE | XFS_IDONTCACHE);
 261        XFS_STATS_INC(xs_ig_found);
 262
 263        return 0;
 264
 265out_error:
 266        spin_unlock(&ip->i_flags_lock);
 267        rcu_read_unlock();
 268        return error;
 269}
 270
 271
 272static int
 273xfs_iget_cache_miss(
 274        struct xfs_mount        *mp,
 275        struct xfs_perag        *pag,
 276        xfs_trans_t             *tp,
 277        xfs_ino_t               ino,
 278        struct xfs_inode        **ipp,
 279        int                     flags,
 280        int                     lock_flags)
 281{
 282        struct xfs_inode        *ip;
 283        int                     error;
 284        xfs_agino_t             agino = XFS_INO_TO_AGINO(mp, ino);
 285        int                     iflags;
 286
 287        ip = xfs_inode_alloc(mp, ino);
 288        if (!ip)
 289                return ENOMEM;
 290
 291        error = xfs_iread(mp, tp, ip, flags);
 292        if (error)
 293                goto out_destroy;
 294
 295        trace_xfs_iget_miss(ip);
 296
 297        if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
 298                error = ENOENT;
 299                goto out_destroy;
 300        }
 301
 302        /*
 303         * Preload the radix tree so we can insert safely under the
 304         * write spinlock. Note that we cannot sleep inside the preload
 305         * region. Since we can be called from transaction context, don't
 306         * recurse into the file system.
 307         */
 308        if (radix_tree_preload(GFP_NOFS)) {
 309                error = EAGAIN;
 310                goto out_destroy;
 311        }
 312
 313        /*
 314         * Because the inode hasn't been added to the radix-tree yet it can't
 315         * be found by another thread, so we can do the non-sleeping lock here.
 316         */
 317        if (lock_flags) {
 318                if (!xfs_ilock_nowait(ip, lock_flags))
 319                        BUG();
 320        }
 321
 322        /*
 323         * These values must be set before inserting the inode into the radix
 324         * tree as the moment it is inserted a concurrent lookup (allowed by the
 325         * RCU locking mechanism) can find it and that lookup must see that this
 326         * is an inode currently under construction (i.e. that XFS_INEW is set).
 327         * The ip->i_flags_lock that protects the XFS_INEW flag forms the
 328         * memory barrier that ensures this detection works correctly at lookup
 329         * time.
 330         */
 331        iflags = XFS_INEW;
 332        if (flags & XFS_IGET_DONTCACHE)
 333                iflags |= XFS_IDONTCACHE;
 334        ip->i_udquot = ip->i_gdquot = NULL;
 335        xfs_iflags_set(ip, iflags);
 336
 337        /* insert the new inode */
 338        spin_lock(&pag->pag_ici_lock);
 339        error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
 340        if (unlikely(error)) {
 341                WARN_ON(error != -EEXIST);
 342                XFS_STATS_INC(xs_ig_dup);
 343                error = EAGAIN;
 344                goto out_preload_end;
 345        }
 346        spin_unlock(&pag->pag_ici_lock);
 347        radix_tree_preload_end();
 348
 349        *ipp = ip;
 350        return 0;
 351
 352out_preload_end:
 353        spin_unlock(&pag->pag_ici_lock);
 354        radix_tree_preload_end();
 355        if (lock_flags)
 356                xfs_iunlock(ip, lock_flags);
 357out_destroy:
 358        __destroy_inode(VFS_I(ip));
 359        xfs_inode_free(ip);
 360        return error;
 361}
 362
 363/*
 364 * Look up an inode by number in the given file system.
 365 * The inode is looked up in the cache held in each AG.
 366 * If the inode is found in the cache, initialise the vfs inode
 367 * if necessary.
 368 *
 369 * If it is not in core, read it in from the file system's device,
 370 * add it to the cache and initialise the vfs inode.
 371 *
 372 * The inode is locked according to the value of the lock_flags parameter.
 373 * This flag parameter indicates how and if the inode's IO lock and inode lock
 374 * should be taken.
 375 *
 376 * mp -- the mount point structure for the current file system.  It points
 377 *       to the inode hash table.
 378 * tp -- a pointer to the current transaction if there is one.  This is
 379 *       simply passed through to the xfs_iread() call.
 380 * ino -- the number of the inode desired.  This is the unique identifier
 381 *        within the file system for the inode being requested.
 382 * lock_flags -- flags indicating how to lock the inode.  See the comment
 383 *               for xfs_ilock() for a list of valid values.
 384 */
 385int
 386xfs_iget(
 387        xfs_mount_t     *mp,
 388        xfs_trans_t     *tp,
 389        xfs_ino_t       ino,
 390        uint            flags,
 391        uint            lock_flags,
 392        xfs_inode_t     **ipp)
 393{
 394        xfs_inode_t     *ip;
 395        int             error;
 396        xfs_perag_t     *pag;
 397        xfs_agino_t     agino;
 398
 399        /*
 400         * xfs_reclaim_inode() uses the ILOCK to ensure an inode
 401         * doesn't get freed while it's being referenced during a
 402         * radix tree traversal here.  It assumes this function
 403         * aqcuires only the ILOCK (and therefore it has no need to
 404         * involve the IOLOCK in this synchronization).
 405         */
 406        ASSERT((lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) == 0);
 407
 408        /* reject inode numbers outside existing AGs */
 409        if (!ino || XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
 410                return EINVAL;
 411
 412        /* get the perag structure and ensure that it's inode capable */
 413        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
 414        agino = XFS_INO_TO_AGINO(mp, ino);
 415
 416again:
 417        error = 0;
 418        rcu_read_lock();
 419        ip = radix_tree_lookup(&pag->pag_ici_root, agino);
 420
 421        if (ip) {
 422                error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
 423                if (error)
 424                        goto out_error_or_again;
 425        } else {
 426                rcu_read_unlock();
 427                XFS_STATS_INC(xs_ig_missed);
 428
 429                error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
 430                                                        flags, lock_flags);
 431                if (error)
 432                        goto out_error_or_again;
 433        }
 434        xfs_perag_put(pag);
 435
 436        *ipp = ip;
 437
 438        /*
 439         * If we have a real type for an on-disk inode, we can set ops(&unlock)
 440         * now.  If it's a new inode being created, xfs_ialloc will handle it.
 441         */
 442        if (xfs_iflags_test(ip, XFS_INEW) && ip->i_d.di_mode != 0)
 443                xfs_setup_inode(ip);
 444        return 0;
 445
 446out_error_or_again:
 447        if (error == EAGAIN) {
 448                delay(1);
 449                goto again;
 450        }
 451        xfs_perag_put(pag);
 452        return error;
 453}
 454
 455/*
 456 * This is a wrapper routine around the xfs_ilock() routine
 457 * used to centralize some grungy code.  It is used in places
 458 * that wish to lock the inode solely for reading the extents.
 459 * The reason these places can't just call xfs_ilock(SHARED)
 460 * is that the inode lock also guards to bringing in of the
 461 * extents from disk for a file in b-tree format.  If the inode
 462 * is in b-tree format, then we need to lock the inode exclusively
 463 * until the extents are read in.  Locking it exclusively all
 464 * the time would limit our parallelism unnecessarily, though.
 465 * What we do instead is check to see if the extents have been
 466 * read in yet, and only lock the inode exclusively if they
 467 * have not.
 468 *
 469 * The function returns a value which should be given to the
 470 * corresponding xfs_iunlock_map_shared().  This value is
 471 * the mode in which the lock was actually taken.
 472 */
 473uint
 474xfs_ilock_map_shared(
 475        xfs_inode_t     *ip)
 476{
 477        uint    lock_mode;
 478
 479        if ((ip->i_d.di_format == XFS_DINODE_FMT_BTREE) &&
 480            ((ip->i_df.if_flags & XFS_IFEXTENTS) == 0)) {
 481                lock_mode = XFS_ILOCK_EXCL;
 482        } else {
 483                lock_mode = XFS_ILOCK_SHARED;
 484        }
 485
 486        xfs_ilock(ip, lock_mode);
 487
 488        return lock_mode;
 489}
 490
 491/*
 492 * This is simply the unlock routine to go with xfs_ilock_map_shared().
 493 * All it does is call xfs_iunlock() with the given lock_mode.
 494 */
 495void
 496xfs_iunlock_map_shared(
 497        xfs_inode_t     *ip,
 498        unsigned int    lock_mode)
 499{
 500        xfs_iunlock(ip, lock_mode);
 501}
 502
 503/*
 504 * The xfs inode contains 2 locks: a multi-reader lock called the
 505 * i_iolock and a multi-reader lock called the i_lock.  This routine
 506 * allows either or both of the locks to be obtained.
 507 *
 508 * The 2 locks should always be ordered so that the IO lock is
 509 * obtained first in order to prevent deadlock.
 510 *
 511 * ip -- the inode being locked
 512 * lock_flags -- this parameter indicates the inode's locks
 513 *       to be locked.  It can be:
 514 *              XFS_IOLOCK_SHARED,
 515 *              XFS_IOLOCK_EXCL,
 516 *              XFS_ILOCK_SHARED,
 517 *              XFS_ILOCK_EXCL,
 518 *              XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
 519 *              XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
 520 *              XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
 521 *              XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
 522 */
 523void
 524xfs_ilock(
 525        xfs_inode_t             *ip,
 526        uint                    lock_flags)
 527{
 528        /*
 529         * You can't set both SHARED and EXCL for the same lock,
 530         * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
 531         * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
 532         */
 533        ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
 534               (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
 535        ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
 536               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
 537        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
 538
 539        if (lock_flags & XFS_IOLOCK_EXCL)
 540                mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
 541        else if (lock_flags & XFS_IOLOCK_SHARED)
 542                mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
 543
 544        if (lock_flags & XFS_ILOCK_EXCL)
 545                mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
 546        else if (lock_flags & XFS_ILOCK_SHARED)
 547                mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
 548
 549        trace_xfs_ilock(ip, lock_flags, _RET_IP_);
 550}
 551
 552/*
 553 * This is just like xfs_ilock(), except that the caller
 554 * is guaranteed not to sleep.  It returns 1 if it gets
 555 * the requested locks and 0 otherwise.  If the IO lock is
 556 * obtained but the inode lock cannot be, then the IO lock
 557 * is dropped before returning.
 558 *
 559 * ip -- the inode being locked
 560 * lock_flags -- this parameter indicates the inode's locks to be
 561 *       to be locked.  See the comment for xfs_ilock() for a list
 562 *       of valid values.
 563 */
 564int
 565xfs_ilock_nowait(
 566        xfs_inode_t             *ip,
 567        uint                    lock_flags)
 568{
 569        /*
 570         * You can't set both SHARED and EXCL for the same lock,
 571         * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
 572         * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
 573         */
 574        ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
 575               (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
 576        ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
 577               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
 578        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
 579
 580        if (lock_flags & XFS_IOLOCK_EXCL) {
 581                if (!mrtryupdate(&ip->i_iolock))
 582                        goto out;
 583        } else if (lock_flags & XFS_IOLOCK_SHARED) {
 584                if (!mrtryaccess(&ip->i_iolock))
 585                        goto out;
 586        }
 587        if (lock_flags & XFS_ILOCK_EXCL) {
 588                if (!mrtryupdate(&ip->i_lock))
 589                        goto out_undo_iolock;
 590        } else if (lock_flags & XFS_ILOCK_SHARED) {
 591                if (!mrtryaccess(&ip->i_lock))
 592                        goto out_undo_iolock;
 593        }
 594        trace_xfs_ilock_nowait(ip, lock_flags, _RET_IP_);
 595        return 1;
 596
 597 out_undo_iolock:
 598        if (lock_flags & XFS_IOLOCK_EXCL)
 599                mrunlock_excl(&ip->i_iolock);
 600        else if (lock_flags & XFS_IOLOCK_SHARED)
 601                mrunlock_shared(&ip->i_iolock);
 602 out:
 603        return 0;
 604}
 605
 606/*
 607 * xfs_iunlock() is used to drop the inode locks acquired with
 608 * xfs_ilock() and xfs_ilock_nowait().  The caller must pass
 609 * in the flags given to xfs_ilock() or xfs_ilock_nowait() so
 610 * that we know which locks to drop.
 611 *
 612 * ip -- the inode being unlocked
 613 * lock_flags -- this parameter indicates the inode's locks to be
 614 *       to be unlocked.  See the comment for xfs_ilock() for a list
 615 *       of valid values for this parameter.
 616 *
 617 */
 618void
 619xfs_iunlock(
 620        xfs_inode_t             *ip,
 621        uint                    lock_flags)
 622{
 623        /*
 624         * You can't set both SHARED and EXCL for the same lock,
 625         * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
 626         * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
 627         */
 628        ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
 629               (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
 630        ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
 631               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
 632        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
 633        ASSERT(lock_flags != 0);
 634
 635        if (lock_flags & XFS_IOLOCK_EXCL)
 636                mrunlock_excl(&ip->i_iolock);
 637        else if (lock_flags & XFS_IOLOCK_SHARED)
 638                mrunlock_shared(&ip->i_iolock);
 639
 640        if (lock_flags & XFS_ILOCK_EXCL)
 641                mrunlock_excl(&ip->i_lock);
 642        else if (lock_flags & XFS_ILOCK_SHARED)
 643                mrunlock_shared(&ip->i_lock);
 644
 645        trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
 646}
 647
 648/*
 649 * give up write locks.  the i/o lock cannot be held nested
 650 * if it is being demoted.
 651 */
 652void
 653xfs_ilock_demote(
 654        xfs_inode_t             *ip,
 655        uint                    lock_flags)
 656{
 657        ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL));
 658        ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
 659
 660        if (lock_flags & XFS_ILOCK_EXCL)
 661                mrdemote(&ip->i_lock);
 662        if (lock_flags & XFS_IOLOCK_EXCL)
 663                mrdemote(&ip->i_iolock);
 664
 665        trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
 666}
 667
 668#ifdef DEBUG
 669int
 670xfs_isilocked(
 671        xfs_inode_t             *ip,
 672        uint                    lock_flags)
 673{
 674        if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
 675                if (!(lock_flags & XFS_ILOCK_SHARED))
 676                        return !!ip->i_lock.mr_writer;
 677                return rwsem_is_locked(&ip->i_lock.mr_lock);
 678        }
 679
 680        if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
 681                if (!(lock_flags & XFS_IOLOCK_SHARED))
 682                        return !!ip->i_iolock.mr_writer;
 683                return rwsem_is_locked(&ip->i_iolock.mr_lock);
 684        }
 685
 686        ASSERT(0);
 687        return 0;
 688}
 689#endif
 690
 691void
 692__xfs_iflock(
 693        struct xfs_inode        *ip)
 694{
 695        wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
 696        DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);
 697
 698        do {
 699                prepare_to_wait_exclusive(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
 700                if (xfs_isiflocked(ip))
 701                        io_schedule();
 702        } while (!xfs_iflock_nowait(ip));
 703
 704        finish_wait(wq, &wait.wait);
 705}
 706
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