xfs_iget.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 994 行 · 第 1/2 页

 * Do the setup for the various locks within the incore inode.
 */
void
xfs_inode_lock_init(
	xfs_inode_t	*ip,
	vnode_t		*vp)
{
	mrlock_init(&ip->i_lock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
		     "xfsino", (long)vp->v_number);
	mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", vp->v_number);
	init_waitqueue_head(&ip->i_ipin_wait);
	atomic_set(&ip->i_pincount, 0);
	init_sema(&ip->i_flock, 1, "xfsfino", vp->v_number);
}

/*
 * Look for the inode corresponding to the given ino in the hash table.
 * If it is there and its i_transp pointer matches tp, return it.
 * Otherwise, return NULL.
 */
xfs_inode_t *
xfs_inode_incore(xfs_mount_t	*mp,
		 xfs_ino_t	ino,
		 xfs_trans_t	*tp)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*ip;

	ih = XFS_IHASH(mp, ino);
	read_lock(&ih->ih_lock);
	for (ip = ih->ih_next; ip != NULL; ip = ip->i_next) {
		if (ip->i_ino == ino) {
			/*
			 * If we find it and tp matches, return it.
			 * Otherwise break from the loop and return
			 * NULL.
			 */
			if (ip->i_transp == tp) {
				read_unlock(&ih->ih_lock);
				return (ip);
			}
			break;
		}
	}
	read_unlock(&ih->ih_lock);
	return (NULL);
}

/*
 * Decrement reference count of an inode structure and unlock it.
 *
 * ip -- the inode being released
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be released.  See the comment on xfs_iunlock() for a list
 *	 of valid values.
 */
void
xfs_iput(xfs_inode_t	*ip,
	 uint		lock_flags)
{
	vnode_t	*vp = XFS_ITOV(ip);

	vn_trace_entry(vp, "xfs_iput", (inst_t *)__return_address);

	xfs_iunlock(ip, lock_flags);

	VN_RELE(vp);
}

/*
 * Special iput for brand-new inodes that are still locked
 */
void
xfs_iput_new(xfs_inode_t	*ip,
	     uint		lock_flags)
{
	vnode_t		*vp = XFS_ITOV(ip);
	struct inode	*inode = LINVFS_GET_IP(vp);

	vn_trace_entry(vp, "xfs_iput_new", (inst_t *)__return_address);

	if (inode->i_state & I_NEW)
		unlock_new_inode(inode);
	if (lock_flags)
		xfs_iunlock(ip, lock_flags);
	VN_RELE(vp);
}


/*
 * This routine embodies the part of the reclaim code that pulls
 * the inode from the inode hash table and the mount structure's
 * inode list.
 * This should only be called from xfs_reclaim().
 */
void
xfs_ireclaim(xfs_inode_t *ip)
{
	vnode_t		*vp;

	/*
	 * Remove from old hash list and mount list.
	 */
	XFS_STATS_INC(xs_ig_reclaims);

	xfs_iextract(ip);

	/*
	 * Here we do a spurious inode lock in order to coordinate with
	 * xfs_sync().  This is because xfs_sync() references the inodes
	 * in the mount list without taking references on the corresponding
	 * vnodes.  We make that OK here by ensuring that we wait until
	 * the inode is unlocked in xfs_sync() before we go ahead and
	 * free it.  We get both the regular lock and the io lock because
	 * the xfs_sync() code may need to drop the regular one but will
	 * still hold the io lock.
	 */
	xfs_ilock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

	/*
	 * Release dquots (and their references) if any. An inode may escape
	 * xfs_inactive and get here via vn_alloc->vn_reclaim path.
	 */
	XFS_QM_DQDETACH(ip->i_mount, ip);

	/*
	 * Pull our behavior descriptor from the vnode chain.
	 */
	vp = XFS_ITOV_NULL(ip);
	if (vp) {
		vn_bhv_remove(VN_BHV_HEAD(vp), XFS_ITOBHV(ip));
	}

	/*
	 * Free all memory associated with the inode.
	 */
	xfs_idestroy(ip);
}

/*
 * This routine removes an about-to-be-destroyed inode from
 * all of the lists in which it is located with the exception
 * of the behavior chain.
 */
void
xfs_iextract(
	xfs_inode_t	*ip)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*iq;
	xfs_mount_t	*mp;
	xfs_chash_t	*ch;
	xfs_chashlist_t *chl, *chm;
	SPLDECL(s);

	ih = ip->i_hash;
	write_lock(&ih->ih_lock);
	if ((iq = ip->i_next)) {
		iq->i_prevp = ip->i_prevp;
	}
	*ip->i_prevp = iq;
	write_unlock(&ih->ih_lock);

	/*
	 * Remove from cluster hash list
	 *   1) delete the chashlist if this is the last inode on the chashlist
	 *   2) unchain from list of inodes
	 *   3) point chashlist->chl_ip to 'chl_next' if to this inode.
	 */
	mp = ip->i_mount;
	ch = XFS_CHASH(mp, ip->i_blkno);
	s = mutex_spinlock(&ch->ch_lock);

	if (ip->i_cnext == ip) {
		/* Last inode on chashlist */
		ASSERT(ip->i_cnext == ip && ip->i_cprev == ip);
		ASSERT(ip->i_chash != NULL);
		chm=NULL;
		for (chl = ch->ch_list; chl != NULL; chl = chl->chl_next) {
			if (chl->chl_blkno == ip->i_blkno) {
				if (chm == NULL) {
					/* first item on the list */
					ch->ch_list = chl->chl_next;
				} else {
					chm->chl_next = chl->chl_next;
				}
				kmem_zone_free(xfs_chashlist_zone, chl);
				break;
			} else {
				ASSERT(chl->chl_ip != ip);
				chm = chl;
			}
		}
		ASSERT_ALWAYS(chl != NULL);
       } else {
		/* delete one inode from a non-empty list */
		iq = ip->i_cnext;
		iq->i_cprev = ip->i_cprev;
		ip->i_cprev->i_cnext = iq;
		if (ip->i_chash->chl_ip == ip) {
			ip->i_chash->chl_ip = iq;
		}
		ip->i_chash = __return_address;
		ip->i_cprev = __return_address;
		ip->i_cnext = __return_address;
	}
	mutex_spinunlock(&ch->ch_lock, s);

	/*
	 * Remove from mount's inode list.
	 */
	XFS_MOUNT_ILOCK(mp);
	ASSERT((ip->i_mnext != NULL) && (ip->i_mprev != NULL));
	iq = ip->i_mnext;
	iq->i_mprev = ip->i_mprev;
	ip->i_mprev->i_mnext = iq;

	/*
	 * Fix up the head pointer if it points to the inode being deleted.
	 */
	if (mp->m_inodes == ip) {
		if (ip == iq) {
			mp->m_inodes = NULL;
		} else {
			mp->m_inodes = iq;
		}
	}

	/* Deal with the deleted inodes list */
	list_del_init(&ip->i_reclaim);

	mp->m_ireclaims++;
	XFS_MOUNT_IUNLOCK(mp);
}

/*
 * 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) == 0);

	if (lock_flags & XFS_IOLOCK_EXCL) {
		mrupdate(&ip->i_iolock);
	} else if (lock_flags & XFS_IOLOCK_SHARED) {
		mraccess(&ip->i_iolock);
	}
	if (lock_flags & XFS_ILOCK_EXCL) {
		mrupdate(&ip->i_lock);
	} else if (lock_flags & XFS_ILOCK_SHARED) {
		mraccess(&ip->i_lock);
	}
	xfs_ilock_trace(ip, 1, lock_flags, (inst_t *)__return_address);
}

/*
 * 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)
{
	int	iolocked;
	int	ilocked;

	/*
	 * 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) == 0);

	iolocked = 0;
	if (lock_flags & XFS_IOLOCK_EXCL) {
		iolocked = mrtryupdate(&ip->i_iolock);
		if (!iolocked) {
			return 0;
		}
	} else if (lock_flags & XFS_IOLOCK_SHARED) {
		iolocked = mrtryaccess(&ip->i_iolock);
		if (!iolocked) {
			return 0;
		}
	}
	if (lock_flags & XFS_ILOCK_EXCL) {
		ilocked = mrtryupdate(&ip->i_lock);
		if (!ilocked) {
			if (iolocked) {
				mrunlock(&ip->i_iolock);
			}
			return 0;
		}
	} else if (lock_flags & XFS_ILOCK_SHARED) {
		ilocked = mrtryaccess(&ip->i_lock);
		if (!ilocked) {
			if (iolocked) {
				mrunlock(&ip->i_iolock);
			}
			return 0;
		}
	}
	xfs_ilock_trace(ip, 2, lock_flags, (inst_t *)__return_address);
	return 1;
}

/*
 * 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_IUNLOCK_NONOTIFY)) == 0);
	ASSERT(lock_flags != 0);

	if (lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) {
		ASSERT(!(lock_flags & XFS_IOLOCK_SHARED) ||
		       (ismrlocked(&ip->i_iolock, MR_ACCESS)));
		ASSERT(!(lock_flags & XFS_IOLOCK_EXCL) ||
		       (ismrlocked(&ip->i_iolock, MR_UPDATE)));
		mrunlock(&ip->i_iolock);
	}

	if (lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) {
		ASSERT(!(lock_flags & XFS_ILOCK_SHARED) ||
		       (ismrlocked(&ip->i_lock, MR_ACCESS)));
		ASSERT(!(lock_flags & XFS_ILOCK_EXCL) ||
		       (ismrlocked(&ip->i_lock, MR_UPDATE)));
		mrunlock(&ip->i_lock);

		/*
		 * Let the AIL know that this item has been unlocked in case
		 * it is in the AIL and anyone is waiting on it.  Don't do
		 * this if the caller has asked us not to.
		 */
		if (!(lock_flags & XFS_IUNLOCK_NONOTIFY) &&
		     ip->i_itemp != NULL) {
			xfs_trans_unlocked_item(ip->i_mount,
						(xfs_log_item_t*)(ip->i_itemp));
		}
	}
	xfs_ilock_trace(ip, 3, lock_flags, (inst_t *)__return_address);
}

/*
 * 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) {
		ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE));
		mrdemote(&ip->i_lock);
	}
	if (lock_flags & XFS_IOLOCK_EXCL) {
		ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE));
		mrdemote(&ip->i_iolock);
	}
}

/*
 * The following three routines simply manage the i_flock
 * semaphore embedded in the inode.  This semaphore synchronizes
 * processes attempting to flush the in-core inode back to disk.
 */
void
xfs_iflock(xfs_inode_t *ip)
{
	psema(&(ip->i_flock), PINOD|PLTWAIT);
}

int
xfs_iflock_nowait(xfs_inode_t *ip)
{
	return (cpsema(&(ip->i_flock)));
}

void
xfs_ifunlock(xfs_inode_t *ip)
{
	ASSERT(valusema(&(ip->i_flock)) <= 0);
	vsema(&(ip->i_flock));
}