/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_acl.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_quota.h"
#include "xfs_utils.h"
#include "xfs_trans_priv.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_trace.h"
/*
* Define xfs inode iolock lockdep classes. We need to ensure that all active
* inodes are considered the same for lockdep purposes, including inodes that
* are recycled through the XFS_IRECLAIMABLE state. This is the the only way to
* guarantee the locks are considered the same when there are multiple lock
* initialisation siteѕ. Also, define a reclaimable inode class so it is
* obvious in lockdep reports which class the report is against.
*/
static struct lock_class_key xfs_iolock_active;
struct lock_class_key xfs_iolock_reclaimable;
/*
* Allocate and initialise an xfs_inode.
*/
STATIC struct xfs_inode *
xfs_inode_alloc(
struct xfs_mount *mp,
xfs_ino_t ino)
{
struct xfs_inode *ip;
/*
* if this didn't occur in transactions, we could use
* KM_MAYFAIL and return NULL here on ENOMEM. Set the
* code up to do this anyway.
*/
ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
if (!ip)
return NULL;
if (inode_init_always(mp->m_super, VFS_I(ip))) {
kmem_zone_free(xfs_inode_zone, ip);
return NULL;
}
ASSERT(atomic_read(&ip->i_pincount) == 0);
ASSERT(!spin_is_locked(&ip->i_flags_lock));
ASSERT(!xfs_isiflocked(ip));
ASSERT(ip->i_ino == 0);
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
lockdep_set_class_and_name(&ip->i_iolock.mr_lock,
&xfs_iolock_active, "xfs_iolock_active");
/* initialise the xfs inode */
ip->i_ino = ino;
ip->i_mount = mp;
memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
ip->i_afp = NULL;
memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
ip->i_flags = 0;
ip->i_delayed_blks = 0;
memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));
return ip;
}
STATIC void
xfs_inode_free_callback(
struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
struct xfs_inode *ip = XFS_I(inode);
kmem_zone_free(xfs_inode_zone, ip);
}
void
xfs_inode_free(
struct xfs_inode *ip)
{
switch (ip->i_d.di_mode & S_IFMT) {
case S_IFREG:
case S_IFDIR:
case S_IFLNK:
xfs_idestroy_fork(ip, XFS_DATA_FORK);
break;
}
if (ip->i_afp)
xfs_idestroy_fork(ip, XFS_ATTR_FORK);
if (ip->i_itemp) {
/*
* Only if we are shutting down the fs will we see an
* inode still in the AIL. If it is there, we should remove
* it to prevent a use-after-free from occurring.
*/
xfs_log_item_t *lip = &ip->i_itemp->ili_item;
struct xfs_ail *ailp = lip->li_ailp;
ASSERT(((lip->li_flags & XFS_LI_IN_AIL) == 0) ||
XFS_FORCED_SHUTDOWN(ip->i_mount));
if (lip->li_flags & XFS_LI_IN_AIL) {
spin_lock(&ailp->xa_lock);
if (lip->li_flags & XFS_LI_IN_AIL)
xfs_trans_ail_delete(ailp, lip);
else
spin_unlock(&ailp->xa_lock);
}
xfs_inode_item_destroy(ip);
ip->i_itemp = NULL;
}
/* asserts to verify all state is correct here */
ASSERT(atomic_read(&ip->i_pincount) == 0);
ASSERT(!spin_is_locked(&ip->i_flags_lock));
ASSERT(!xfs_isiflocked(ip));
/*
* Because we use RCU freeing we need to ensure the inode always
* appears to be reclaimed with an invalid inode number when in the
* free state. The ip->i_flags_lock provides the barrier against lookup
* races.
*/
spin_lock(&ip->i_flags_lock);
ip->i_flags = XFS_IRECLAIM;
ip->i_ino = 0;
spin_unlock(&ip->i_flags_lock);
call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
}
/*
* Check the validity of the inode we just found it the cache
*/
static int
xfs_iget_cache_hit(
struct xfs_perag *pag,
struct xfs_inode *ip,
xfs_ino_t ino,
int flags,
int lock_flags) __releases(RCU)
{
struct inode *inode = VFS_I(ip);
struct xfs_mount *mp = ip->i_mount;
int error;
/*
* check for re-use of an inode within an RCU grace period due to the
* radix tree nodes not being updated yet. We monitor for this by
* setting the inode number to zero before freeing the inode structure.
* If the inode has been reallocated and set up, then the inode number
* will not match, so check for that, too.
*/
spin_lock(&ip->i_flags_lock);
if (ip->i_ino != ino) {
trace_xfs_iget_skip(ip);
XFS_STATS_INC(xs_ig_frecycle);
error = EAGAIN;
goto out_error;
}
/*
* If we are racing with another cache hit that is currently
* instantiating this inode or currently recycling it out of
* reclaimabe state, wait for the initialisation to complete
* before continuing.
*
* XXX(hch): eventually we should do something equivalent to
* wait_on_inode to wait for these flags to be cleared
* instead of polling for it.
*/
if (ip->i_flags & (XFS_INEW|XFS_IRECLAIM)) {
trace_xfs_iget_skip(ip);
XFS_STATS_INC(xs_ig_frecycle);
error = EAGAIN;
goto out_error;
}
/*
* If lookup is racing with unlink return an error immediately.
*/
if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
error = ENOENT;
goto out_error;
}
/*
* If IRECLAIMABLE is set, we've torn down the VFS inode already.
* Need to carefully get it back into useable state.
*/
if (ip->i_flags & XFS_IRECLAIMABLE) {
trace_xfs_iget_reclaim(ip);
/*
* We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
* from stomping over us while we recycle the inode. We can't
* clear the radix tree reclaimable tag yet as it requires
* pag_ici_lock to be held exclusive.
*/
ip->i_flags |= XFS_IRECLAIM;
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
error = -inode_init_always(mp->m_super, inode);
if (error) {
/*
* Re-initializing the inode failed, and we are in deep
* trouble. Try to re-add it to the reclaim list.
*/
rcu_read_lock();
spin_lock(&ip->i_flags_lock);
ip->i_flags &= ~(XFS_INEW | XFS_IRECLAIM);
ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
trace_xfs_iget_reclaim_fail(ip);
goto out_error;
}
spin_lock(&pag->pag_ici_lock);
spin_lock(&ip->i_flags_lock);
/*
* Clear the per-lifetime state in the inode as we are now
* effectively a new inode and need to return to the initial
* state before reuse occurs.
*/
ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
ip->i_flags |= XFS_INEW;
__xfs_inode_clear_reclaim_tag(mp, pag, ip);
inode->i_state = I_NEW;
ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
lockdep_set_class_and_name(&ip->i_iolock.mr_lock,
&xfs_iolock_active, "xfs_iolock_active");
spin_unlock(&ip->i_flags_lock);
spin_unlock(&pag->pag_ici_lock);
} else {
/* If the VFS inode is being torn down, pause and try again. */
if (!igrab(inode)) {
trace_xfs_iget_skip(ip);
error = EAGAIN;
goto out_error;
}
/* We've got a live one. */
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
trace_xfs_iget_hit(ip);
}
if (lock_flags != 0)
xfs_ilock(ip, lock_flags);
xfs_iflags_clear(ip, XFS_ISTALE | XFS_IDONTCACHE);
XFS_STATS_INC(xs_ig_found);
return 0;
out_error:
spin_unlock(&ip->i_flags_lock);
rcu_read_unlock();
return error;
}
static int
xfs_iget_cache_miss(
struct xfs_mount *mp,
struct xfs_perag *pag,
xfs_trans_t *tp,
xfs_ino_t ino,
struct xfs_inode **ipp,
int flags,
int lock_flags)
{
struct xfs_inode *ip;
int error;
xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ino);
int iflags;
ip = xfs_inode_alloc(mp, ino);
if (!ip)
return ENOMEM;
error = xfs_iread(mp, tp, ip, flags);
if (error)
goto out_destroy;
trace_xfs_iget_miss(ip);
if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
error = ENOENT;
goto out_destroy;
}
/*
* Preload the radix tree so we can insert safely under the
* write spinlock. Note that we cannot sleep inside the preload
* region.
*/
if (radix_tree_preload(GFP_KERNEL)) {
error = EAGAIN;
goto out_destroy;
}
/*
* Because the inode hasn't been added to the radix-tree yet it can't
* be found by another thread, so we can do the non-sleeping lock here.
*/
if (lock_flags) {
if (!xfs_ilock_nowait(ip, lock_flags))
BUG();
}
/*
* These values must be set before inserting the inode into the radix
* tree as the moment it is inserted a concurrent lookup (allowed by the
* RCU locking mechanism) can find it and that lookup must see that this
* is an inode currently under construction (i.e. that XFS_INEW is set).
* The ip->i_flags_lock that protects the XFS_INEW flag forms the
* memory barrier that ensures this detection works correctly at lookup
* time.
*/
iflags = XFS_INEW;
if (flags & XFS_IGET_DONTCACHE)
iflags |= XFS_IDONTCACHE;
ip->i_udquot = ip->i_gdquot = NULL;
xfs_iflags_set(ip, iflags);
/* insert the new inode */
spin_lock(&pag->pag_ici_lock);
error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
if (unlikely(error)) {
WARN_ON(error != -EEXIST);
XFS_STATS_INC(xs_ig_dup);
error = EAGAIN;
goto out_preload_end;
}
spin_unlock(&pag->pag_ici_lock);
radix_tree_preload_end();
*ipp = ip;
return 0;
out_preload_end:
spin_unlock(&pag->pag_ici_lock);
radix_tree_preload_end();
if (lock_flags)
xfs_iunlock(ip, lock_flags);
out_destroy:
__destroy_inode(VFS_I(ip));
xfs_inode_free(ip);
return error;
}
/*
* Look up an inode by number in the given file system.
* The inode is looked up in the cache held in each AG.
* If the inode is found in the cache, initialise the vfs inode
* if necessary.
*
* If it is not in core, read it in from the file system's device,
* add it to the cache and initialise the vfs inode.
*
* The inode is locked according to the value of the lock_flags parameter.
* This flag parameter indicates how and if the inode's IO lock and inode lock
* should be taken.
*
* mp -- the mount point structure for the current file system. It points
* to the inode hash table.
* tp -- a pointer to the current transaction if there is one. This is
* simply passed through to the xfs_iread() call.
* ino -- the number of the inode desired. This is the unique identifier
* within the file system for the inode being requested.
* lock_flags -- flags indicating how to lock the inode. See the comment
* for xfs_ilock() for a list of valid values.
*/
int
xfs_iget(
xfs_mount_t *mp,
xfs_trans_t *tp,
xfs_ino_t ino,
uint flags,
uint lock_flags,
xfs_inode_t **ipp)
{
xfs_inode_t *ip;
int error;
xfs_perag_t *pag;
xfs_agino_t agino;
/*
* xfs_reclaim_inode() uses the ILOCK to ensure an inode
* doesn't get freed while it's being referenced during a
* radix tree traversal here. It assumes this function
* aqcuires only the ILOCK (and therefore it has no need to
* involve the IOLOCK in this synchronization).
*/
ASSERT((lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) == 0);
/* reject inode numbers outside existing AGs */
if (!ino || XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
return EINVAL;
/* get the perag structure and ensure that it's inode capable */
pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
agino = XFS_INO_TO_AGINO(mp, ino);
again:
error = 0;
rcu_read_lock();
ip = radix_tree_lookup(&pag->pag_ici_root, agino);
if (ip) {
error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
if (error)
goto out_error_or_again;
} else {
rcu_read_unlock();
XFS_STATS_INC(xs_ig_missed);
error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
flags, lock_flags);
if (error)
goto out_error_or_again;
}
xfs_perag_put(pag);
*ipp = ip;
/*
* If we have a real type for an on-disk inode, we can set ops(&unlock)
* now. If it's a new inode being created, xfs_ialloc will handle it.
*/
if (xfs_iflags_test(ip, XFS_INEW) && ip->i_d.di_mode != 0)
xfs_setup_inode(ip);
return 0;
out_error_or_again:
if (error == EAGAIN) {
delay(1);
goto again;
}
xfs_perag_put(pag);
return error;
}
/*
* This is a wrapper routine around the xfs_ilock() routine
* used to centralize some grungy code. It is used in places
* that wish to lock the inode solely for reading the extents.
* The reason these places can't just call xfs_ilock(SHARED)
* is that the inode lock also guards to bringing in of the
* extents from disk for a file in b-tree format. If the inode
* is in b-tree format, then we need to lock the inode exclusively
* until the extents are read in. Locking it exclusively all
* the time would limit our parallelism unnecessarily, though.
* What we do instead is check to see if the extents have been
* read in yet, and only lock the inode exclusively if they
* have not.
*
* The function returns a value which should be given to the
* corresponding xfs_iunlock_map_shared(). This value is
* the mode in which the lock was actually taken.
*/
uint
xfs_ilock_map_shared(
xfs_inode_t *ip)
{
uint lock_mode;
if ((ip->i_d.di_format == XFS_DINODE_FMT_BTREE) &&
((ip->i_df.if_flags & XFS_IFEXTENTS) == 0)) {
lock_mode = XFS_ILOCK_EXCL;
} else {
lock_mode = XFS_ILOCK_SHARED;
}
xfs_ilock(ip, lock_mode);
return lock_mode;
}
/*
* This is simply the unlock routine to go with xfs_ilock_map_shared().
* All it does is call xfs_iunlock() with the given lock_mode.
*/
void
xfs_iunlock_map_shared(
xfs_inode_t *ip,
unsigned int lock_mode)
{
xfs_iunlock(ip, lock_mode);
}
/*
* The xfs inode contains 2 locks: a multi-reader lock called the
* i_iolock and a multi-reader lock called the i_lock. This routine
* allows either or both of the locks to be obtained.
*
* The 2 locks should always be ordered so that the IO lock is
* obtained first in order to prevent deadlock.
*
* ip -- the inode being locked
* lock_flags -- this parameter indicates the inode's locks
* to be locked. It can be:
* XFS_IOLOCK_SHARED,
* XFS_IOLOCK_EXCL,
* XFS_ILOCK_SHARED,
* XFS_ILOCK_EXCL,
* XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
* XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
* XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
* XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
*/
void
xfs_ilock(
xfs_inode_t *ip,
uint lock_flags)
{
/*
* You can't set both SHARED and EXCL for the same lock,
* and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
* and XFS_ILOCK_EXCL are valid values to set in lock_flags.
*/
ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
if (lock_flags & XFS_IOLOCK_EXCL)
mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
else if (lock_flags & XFS_IOLOCK_SHARED)
mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
if (lock_flags & XFS_ILOCK_EXCL)
mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
else if (lock_flags & XFS_ILOCK_SHARED)
mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
trace_xfs_ilock(ip, lock_flags, _RET_IP_);
}
/*
* This is just like xfs_ilock(), except that the caller
* is guaranteed not to sleep. It returns 1 if it gets
* the requested locks and 0 otherwise. If the IO lock is
* obtained but the inode lock cannot be, then the IO lock
* is dropped before returning.
*
* ip -- the inode being locked
* lock_flags -- this parameter indicates the inode's locks to be
* to be locked. See the comment for xfs_ilock() for a list
* of valid values.
*/
int
xfs_ilock_nowait(
xfs_inode_t *ip,
uint lock_flags)
{
/*
* You can't set both SHARED and EXCL for the same lock,
* and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
* and XFS_ILOCK_EXCL are valid values to set in lock_flags.
*/
ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
if (lock_flags & XFS_IOLOCK_EXCL) {
if (!mrtryupdate(&ip->i_iolock))
goto out;
} else if (lock_flags & XFS_IOLOCK_SHARED) {
if (!mrtryaccess(&ip->i_iolock))
goto out;
}
if (lock_flags & XFS_ILOCK_EXCL) {
if (!mrtryupdate(&ip->i_lock))
goto out_undo_iolock;
} else if (lock_flags & XFS_ILOCK_SHARED) {
if (!mrtryaccess(&ip->i_lock))
goto out_undo_iolock;
}
trace_xfs_ilock_nowait(ip, lock_flags, _RET_IP_);
return 1;
out_undo_iolock:
if (lock_flags & XFS_IOLOCK_EXCL)
mrunlock_excl(&ip->i_iolock);
else if (lock_flags & XFS_IOLOCK_SHARED)
mrunlock_shared(&ip->i_iolock);
out:
return 0;
}
/*
* xfs_iunlock() is used to drop the inode locks acquired with
* xfs_ilock() and xfs_ilock_nowait(). The caller must pass
* in the flags given to xfs_ilock() or xfs_ilock_nowait() so
* that we know which locks to drop.
*
* ip -- the inode being unlocked
* lock_flags -- this parameter indicates the inode's locks to be
* to be unlocked. See the comment for xfs_ilock() for a list
* of valid values for this parameter.
*
*/
void
xfs_iunlock(
xfs_inode_t *ip,
uint lock_flags)
{
/*
* You can't set both SHARED and EXCL for the same lock,
* and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
* and XFS_ILOCK_EXCL are valid values to set in lock_flags.
*/
ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
(XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
ASSERT(lock_flags != 0);
if (lock_flags & XFS_IOLOCK_EXCL)
mrunlock_excl(&ip->i_iolock);
else if (lock_flags & XFS_IOLOCK_SHARED)
mrunlock_shared(&ip->i_iolock);
if (lock_flags & XFS_ILOCK_EXCL)
mrunlock_excl(&ip->i_lock);
else if (lock_flags & XFS_ILOCK_SHARED)
mrunlock_shared(&ip->i_lock);
trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
}
/*
* give up write locks. the i/o lock cannot be held nested
* if it is being demoted.
*/
void
xfs_ilock_demote(
xfs_inode_t *ip,
uint lock_flags)
{
ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL));
ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
if (lock_flags & XFS_ILOCK_EXCL)
mrdemote(&ip->i_lock);
if (lock_flags & XFS_IOLOCK_EXCL)
mrdemote(&ip->i_iolock);
trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
}
#ifdef DEBUG
int
xfs_isilocked(
xfs_inode_t *ip,
uint lock_flags)
{
if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
if (!(lock_flags & XFS_ILOCK_SHARED))
return !!ip->i_lock.mr_writer;
return rwsem_is_locked(&ip->i_lock.mr_lock);
}
if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
if (!(lock_flags & XFS_IOLOCK_SHARED))
return !!ip->i_iolock.mr_writer;
return rwsem_is_locked(&ip->i_iolock.mr_lock);
}
ASSERT(0);
return 0;
}
#endif
void
__xfs_iflock(
struct xfs_inode *ip)
{
wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);
do {
prepare_to_wait_exclusive(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
if (xfs_isiflocked(ip))
io_schedule();
} while (!xfs_iflock_nowait(ip));
finish_wait(wq, &wait.wait);
}