xfs_iget.c

linux 内核源代码

/*
 * 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_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.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"

/*
 * 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, attach it to the provided
 * vnode.
 *
 * If it is not in core, read it in from the file system's device,
 * add it to the cache and attach the provided vnode.
 *
 * 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.
 * bno -- the block number starting the buffer containing the inode,
 *	  if known (as by bulkstat), else 0.
 */
STATIC int
xfs_iget_core(
	bhv_vnode_t	*vp,
	xfs_mount_t	*mp,
	xfs_trans_t	*tp,
	xfs_ino_t	ino,
	uint		flags,
	uint		lock_flags,
	xfs_inode_t	**ipp,
	xfs_daddr_t	bno)
{
	xfs_inode_t	*ip;
	xfs_inode_t	*iq;
	bhv_vnode_t	*inode_vp;
	int		error;
	xfs_icluster_t	*icl, *new_icl = NULL;
	unsigned long	first_index, mask;
	xfs_perag_t	*pag;
	xfs_agino_t	agino;

	/* the radix tree exists only in inode capable AGs */
	if (XFS_INO_TO_AGNO(mp, ino) >= mp->m_maxagi)
		return EINVAL;

	/* get the perag structure and ensure that it's inode capable */
	pag = xfs_get_perag(mp, ino);
	if (!pag->pagi_inodeok)
		return EINVAL;
	ASSERT(pag->pag_ici_init);
	agino = XFS_INO_TO_AGINO(mp, ino);

again:
	read_lock(&pag->pag_ici_lock);
	ip = radix_tree_lookup(&pag->pag_ici_root, agino);

	if (ip != NULL) {
		/*
		 * If INEW is set this inode is being set up
		 * we need to pause and try again.
		 */
		if (xfs_iflags_test(ip, XFS_INEW)) {
			read_unlock(&pag->pag_ici_lock);
			delay(1);
			XFS_STATS_INC(xs_ig_frecycle);

			goto again;
		}

		inode_vp = XFS_ITOV_NULL(ip);
		if (inode_vp == NULL) {
			/*
			 * If IRECLAIM is set this inode is
			 * on its way out of the system,
			 * we need to pause and try again.
			 */
			if (xfs_iflags_test(ip, XFS_IRECLAIM)) {
				read_unlock(&pag->pag_ici_lock);
				delay(1);
				XFS_STATS_INC(xs_ig_frecycle);

				goto again;
			}
			ASSERT(xfs_iflags_test(ip, XFS_IRECLAIMABLE));

			/*
			 * If lookup is racing with unlink, then we
			 * should return an error immediately so we
			 * don't remove it from the reclaim list and
			 * potentially leak the inode.
			 */
			if ((ip->i_d.di_mode == 0) &&
			    !(flags & XFS_IGET_CREATE)) {
				read_unlock(&pag->pag_ici_lock);
				xfs_put_perag(mp, pag);
				return ENOENT;
			}

			/*
			 * There may be transactions sitting in the
			 * incore log buffers or being flushed to disk
			 * at this time.  We can't clear the
			 * XFS_IRECLAIMABLE flag until these
			 * transactions have hit the disk, otherwise we
			 * will void the guarantee the flag provides
			 * xfs_iunpin()
			 */
			if (xfs_ipincount(ip)) {
				read_unlock(&pag->pag_ici_lock);
				xfs_log_force(mp, 0,
					XFS_LOG_FORCE|XFS_LOG_SYNC);
				XFS_STATS_INC(xs_ig_frecycle);
				goto again;
			}

			vn_trace_exit(ip, "xfs_iget.alloc",
				(inst_t *)__return_address);

			XFS_STATS_INC(xs_ig_found);

			xfs_iflags_clear(ip, XFS_IRECLAIMABLE);
			read_unlock(&pag->pag_ici_lock);

			XFS_MOUNT_ILOCK(mp);
			list_del_init(&ip->i_reclaim);
			XFS_MOUNT_IUNLOCK(mp);

			goto finish_inode;

		} else if (vp != inode_vp) {
			struct inode *inode = vn_to_inode(inode_vp);

			/* The inode is being torn down, pause and
			 * try again.
			 */
			if (inode->i_state & (I_FREEING | I_CLEAR)) {
				read_unlock(&pag->pag_ici_lock);
				delay(1);
				XFS_STATS_INC(xs_ig_frecycle);

				goto again;
			}
/* Chances are the other vnode (the one in the inode) is being torn
* down right now, and we landed on top of it. Question is, what do
* we do? Unhook the old inode and hook up the new one?
*/
			cmn_err(CE_PANIC,
		"xfs_iget_core: ambiguous vns: vp/0x%p, invp/0x%p",
					inode_vp, vp);
		}

		/*
		 * Inode cache hit
		 */
		read_unlock(&pag->pag_ici_lock);
		XFS_STATS_INC(xs_ig_found);

finish_inode:
		if (ip->i_d.di_mode == 0) {
			if (!(flags & XFS_IGET_CREATE)) {
				xfs_put_perag(mp, pag);
				return ENOENT;
			}
			xfs_iocore_inode_reinit(ip);
		}

		if (lock_flags != 0)
			xfs_ilock(ip, lock_flags);

		xfs_iflags_clear(ip, XFS_ISTALE);
		vn_trace_exit(ip, "xfs_iget.found",
					(inst_t *)__return_address);
		goto return_ip;
	}

	/*
	 * Inode cache miss
	 */
	read_unlock(&pag->pag_ici_lock);
	XFS_STATS_INC(xs_ig_missed);

	/*
	 * Read the disk inode attributes into a new inode structure and get
	 * a new vnode for it. This should also initialize i_ino and i_mount.
	 */
	error = xfs_iread(mp, tp, ino, &ip, bno,
			  (flags & XFS_IGET_BULKSTAT) ? XFS_IMAP_BULKSTAT : 0);
	if (error) {
		xfs_put_perag(mp, pag);
		return error;
	}

	vn_trace_exit(ip, "xfs_iget.alloc", (inst_t *)__return_address);

	xfs_inode_lock_init(ip, vp);
	xfs_iocore_inode_init(ip);
	if (lock_flags)
		xfs_ilock(ip, lock_flags);

	if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
		xfs_idestroy(ip);
		xfs_put_perag(mp, pag);
		return ENOENT;
	}

	/*
	 * This is a bit messy - we preallocate everything we _might_
	 * need before we pick up the ici lock. That way we don't have to
	 * juggle locks and go all the way back to the start.
	 */
	new_icl = kmem_zone_alloc(xfs_icluster_zone, KM_SLEEP);
	if (radix_tree_preload(GFP_KERNEL)) {
		delay(1);
		goto again;
	}
	mask = ~(((XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog)) - 1);
	first_index = agino & mask;
	write_lock(&pag->pag_ici_lock);

	/*
	 * Find the cluster if it exists
	 */
	icl = NULL;
	if (radix_tree_gang_lookup(&pag->pag_ici_root, (void**)&iq,
							first_index, 1)) {
		if ((XFS_INO_TO_AGINO(mp, iq->i_ino) & mask) == first_index)
			icl = iq->i_cluster;
	}

	/*
	 * insert the new inode
	 */
	error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
	if (unlikely(error)) {
		BUG_ON(error != -EEXIST);
		write_unlock(&pag->pag_ici_lock);
		radix_tree_preload_end();
		xfs_idestroy(ip);
		XFS_STATS_INC(xs_ig_dup);
		goto again;
	}

	/*
	 * These values _must_ be set before releasing ihlock!
	 */
	ip->i_udquot = ip->i_gdquot = NULL;
	xfs_iflags_set(ip, XFS_INEW);

	ASSERT(ip->i_cluster == NULL);

	if (!icl) {
		spin_lock_init(&new_icl->icl_lock);
		INIT_HLIST_HEAD(&new_icl->icl_inodes);
		icl = new_icl;
		new_icl = NULL;
	} else {
		ASSERT(!hlist_empty(&icl->icl_inodes));
	}
	spin_lock(&icl->icl_lock);
	hlist_add_head(&ip->i_cnode, &icl->icl_inodes);
	ip->i_cluster = icl;
	spin_unlock(&icl->icl_lock);

	write_unlock(&pag->pag_ici_lock);
	radix_tree_preload_end();
	if (new_icl)
		kmem_zone_free(xfs_icluster_zone, new_icl);

	/*
	 * Link ip to its mount and thread it on the mount's inode list.
	 */
	XFS_MOUNT_ILOCK(mp);
	if ((iq = mp->m_inodes)) {
		ASSERT(iq->i_mprev->i_mnext == iq);
		ip->i_mprev = iq->i_mprev;
		iq->i_mprev->i_mnext = ip;
		iq->i_mprev = ip;
		ip->i_mnext = iq;
	} else {
		ip->i_mnext = ip;
		ip->i_mprev = ip;
	}
	mp->m_inodes = ip;

	XFS_MOUNT_IUNLOCK(mp);
	xfs_put_perag(mp, pag);

 return_ip:
	ASSERT(ip->i_df.if_ext_max ==
	       XFS_IFORK_DSIZE(ip) / sizeof(xfs_bmbt_rec_t));

	ASSERT(((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) != 0) ==
	       ((ip->i_iocore.io_flags & XFS_IOCORE_RT) != 0));

	xfs_iflags_set(ip, XFS_IMODIFIED);
	*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.
	 */
	xfs_initialize_vnode(mp, vp, ip);
	return 0;
}


/*
 * The 'normal' internal xfs_iget, if needed it will
 * 'allocate', or 'get', the vnode.
 */
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_daddr_t	bno)
{
	struct inode	*inode;
	bhv_vnode_t	*vp = NULL;
	int		error;

	XFS_STATS_INC(xs_ig_attempts);

retry:
	inode = iget_locked(mp->m_super, ino);
	if (inode) {
		xfs_inode_t	*ip;

		vp = vn_from_inode(inode);
		if (inode->i_state & I_NEW) {
			vn_initialize(inode);
			error = xfs_iget_core(vp, mp, tp, ino, flags,
					lock_flags, ipp, bno);
			if (error) {
				vn_mark_bad(vp);
				if (inode->i_state & I_NEW)
					unlock_new_inode(inode);
				iput(inode);
			}
		} else {
			/*
			 * If the inode is not fully constructed due to
			 * filehandle mismatches wait for the inode to go
			 * away and try again.
			 *
			 * iget_locked will call __wait_on_freeing_inode
			 * to wait for the inode to go away.
			 */
			if (is_bad_inode(inode) ||
			    ((ip = xfs_vtoi(vp)) == NULL)) {
				iput(inode);
				delay(1);
				goto retry;
			}

			if (lock_flags != 0)
				xfs_ilock(ip, lock_flags);
			XFS_STATS_INC(xs_ig_found);
			*ipp = ip;
			error = 0;
		}
	} else
		error = ENOMEM;	/* If we got no inode we are out of memory */

	return error;
}

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

/*
 * 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.
 */