dlmglue.c

linux 内核源代码

		cpu_to_be64(ocfs2_pack_timespec(&inode->i_atime));
	lvb->lvb_ictime_packed =
		cpu_to_be64(ocfs2_pack_timespec(&inode->i_ctime));
	lvb->lvb_imtime_packed =
		cpu_to_be64(ocfs2_pack_timespec(&inode->i_mtime));
	lvb->lvb_iattr    = cpu_to_be32(oi->ip_attr);
	lvb->lvb_idynfeatures = cpu_to_be16(oi->ip_dyn_features);
	lvb->lvb_igeneration = cpu_to_be32(inode->i_generation);

out:
	mlog_meta_lvb(0, lockres);

	mlog_exit_void();
}

static void ocfs2_unpack_timespec(struct timespec *spec,
				  u64 packed_time)
{
	spec->tv_sec = packed_time >> OCFS2_SEC_SHIFT;
	spec->tv_nsec = packed_time & OCFS2_NSEC_MASK;
}

static void ocfs2_refresh_inode_from_lvb(struct inode *inode)
{
	struct ocfs2_inode_info *oi = OCFS2_I(inode);
	struct ocfs2_lock_res *lockres = &oi->ip_meta_lockres;
	struct ocfs2_meta_lvb *lvb;

	mlog_entry_void();

	mlog_meta_lvb(0, lockres);

	lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;

	/* We're safe here without the lockres lock... */
	spin_lock(&oi->ip_lock);
	oi->ip_clusters = be32_to_cpu(lvb->lvb_iclusters);
	i_size_write(inode, be64_to_cpu(lvb->lvb_isize));

	oi->ip_attr = be32_to_cpu(lvb->lvb_iattr);
	oi->ip_dyn_features = be16_to_cpu(lvb->lvb_idynfeatures);
	ocfs2_set_inode_flags(inode);

	/* fast-symlinks are a special case */
	if (S_ISLNK(inode->i_mode) && !oi->ip_clusters)
		inode->i_blocks = 0;
	else
		inode->i_blocks = ocfs2_inode_sector_count(inode);

	inode->i_uid     = be32_to_cpu(lvb->lvb_iuid);
	inode->i_gid     = be32_to_cpu(lvb->lvb_igid);
	inode->i_mode    = be16_to_cpu(lvb->lvb_imode);
	inode->i_nlink   = be16_to_cpu(lvb->lvb_inlink);
	ocfs2_unpack_timespec(&inode->i_atime,
			      be64_to_cpu(lvb->lvb_iatime_packed));
	ocfs2_unpack_timespec(&inode->i_mtime,
			      be64_to_cpu(lvb->lvb_imtime_packed));
	ocfs2_unpack_timespec(&inode->i_ctime,
			      be64_to_cpu(lvb->lvb_ictime_packed));
	spin_unlock(&oi->ip_lock);

	mlog_exit_void();
}

static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
					      struct ocfs2_lock_res *lockres)
{
	struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;

	if (lvb->lvb_version == OCFS2_LVB_VERSION
	    && be32_to_cpu(lvb->lvb_igeneration) == inode->i_generation)
		return 1;
	return 0;
}

/* Determine whether a lock resource needs to be refreshed, and
 * arbitrate who gets to refresh it.
 *
 *   0 means no refresh needed.
 *
 *   > 0 means you need to refresh this and you MUST call
 *   ocfs2_complete_lock_res_refresh afterwards. */
static int ocfs2_should_refresh_lock_res(struct ocfs2_lock_res *lockres)
{
	unsigned long flags;
	int status = 0;

	mlog_entry_void();

refresh_check:
	spin_lock_irqsave(&lockres->l_lock, flags);
	if (!(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH)) {
		spin_unlock_irqrestore(&lockres->l_lock, flags);
		goto bail;
	}

	if (lockres->l_flags & OCFS2_LOCK_REFRESHING) {
		spin_unlock_irqrestore(&lockres->l_lock, flags);

		ocfs2_wait_on_refreshing_lock(lockres);
		goto refresh_check;
	}

	/* Ok, I'll be the one to refresh this lock. */
	lockres_or_flags(lockres, OCFS2_LOCK_REFRESHING);
	spin_unlock_irqrestore(&lockres->l_lock, flags);

	status = 1;
bail:
	mlog_exit(status);
	return status;
}

/* If status is non zero, I'll mark it as not being in refresh
 * anymroe, but i won't clear the needs refresh flag. */
static inline void ocfs2_complete_lock_res_refresh(struct ocfs2_lock_res *lockres,
						   int status)
{
	unsigned long flags;
	mlog_entry_void();

	spin_lock_irqsave(&lockres->l_lock, flags);
	lockres_clear_flags(lockres, OCFS2_LOCK_REFRESHING);
	if (!status)
		lockres_clear_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
	spin_unlock_irqrestore(&lockres->l_lock, flags);

	wake_up(&lockres->l_event);

	mlog_exit_void();
}

/* may or may not return a bh if it went to disk. */
static int ocfs2_meta_lock_update(struct inode *inode,
				  struct buffer_head **bh)
{
	int status = 0;
	struct ocfs2_inode_info *oi = OCFS2_I(inode);
	struct ocfs2_lock_res *lockres = &oi->ip_meta_lockres;
	struct ocfs2_dinode *fe;
	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

	mlog_entry_void();

	if (ocfs2_mount_local(osb))
		goto bail;

	spin_lock(&oi->ip_lock);
	if (oi->ip_flags & OCFS2_INODE_DELETED) {
		mlog(0, "Orphaned inode %llu was deleted while we "
		     "were waiting on a lock. ip_flags = 0x%x\n",
		     (unsigned long long)oi->ip_blkno, oi->ip_flags);
		spin_unlock(&oi->ip_lock);
		status = -ENOENT;
		goto bail;
	}
	spin_unlock(&oi->ip_lock);

	if (!ocfs2_should_refresh_lock_res(lockres))
		goto bail;

	/* This will discard any caching information we might have had
	 * for the inode metadata. */
	ocfs2_metadata_cache_purge(inode);

	ocfs2_extent_map_trunc(inode, 0);

	if (ocfs2_meta_lvb_is_trustable(inode, lockres)) {
		mlog(0, "Trusting LVB on inode %llu\n",
		     (unsigned long long)oi->ip_blkno);
		ocfs2_refresh_inode_from_lvb(inode);
	} else {
		/* Boo, we have to go to disk. */
		/* read bh, cast, ocfs2_refresh_inode */
		status = ocfs2_read_block(OCFS2_SB(inode->i_sb), oi->ip_blkno,
					  bh, OCFS2_BH_CACHED, inode);
		if (status < 0) {
			mlog_errno(status);
			goto bail_refresh;
		}
		fe = (struct ocfs2_dinode *) (*bh)->b_data;

		/* This is a good chance to make sure we're not
		 * locking an invalid object.
		 *
		 * We bug on a stale inode here because we checked
		 * above whether it was wiped from disk. The wiping
		 * node provides a guarantee that we receive that
		 * message and can mark the inode before dropping any
		 * locks associated with it. */
		if (!OCFS2_IS_VALID_DINODE(fe)) {
			OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, fe);
			status = -EIO;
			goto bail_refresh;
		}
		mlog_bug_on_msg(inode->i_generation !=
				le32_to_cpu(fe->i_generation),
				"Invalid dinode %llu disk generation: %u "
				"inode->i_generation: %u\n",
				(unsigned long long)oi->ip_blkno,
				le32_to_cpu(fe->i_generation),
				inode->i_generation);
		mlog_bug_on_msg(le64_to_cpu(fe->i_dtime) ||
				!(fe->i_flags & cpu_to_le32(OCFS2_VALID_FL)),
				"Stale dinode %llu dtime: %llu flags: 0x%x\n",
				(unsigned long long)oi->ip_blkno,
				(unsigned long long)le64_to_cpu(fe->i_dtime),
				le32_to_cpu(fe->i_flags));

		ocfs2_refresh_inode(inode, fe);
	}

	status = 0;
bail_refresh:
	ocfs2_complete_lock_res_refresh(lockres, status);
bail:
	mlog_exit(status);
	return status;
}

static int ocfs2_assign_bh(struct inode *inode,
			   struct buffer_head **ret_bh,
			   struct buffer_head *passed_bh)
{
	int status;

	if (passed_bh) {
		/* Ok, the update went to disk for us, use the
		 * returned bh. */
		*ret_bh = passed_bh;
		get_bh(*ret_bh);

		return 0;
	}

	status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
				  OCFS2_I(inode)->ip_blkno,
				  ret_bh,
				  OCFS2_BH_CACHED,
				  inode);
	if (status < 0)
		mlog_errno(status);

	return status;
}

/*
 * returns < 0 error if the callback will never be called, otherwise
 * the result of the lock will be communicated via the callback.
 */
int ocfs2_meta_lock_full(struct inode *inode,
			 struct buffer_head **ret_bh,
			 int ex,
			 int arg_flags)
{
	int status, level, dlm_flags, acquired;
	struct ocfs2_lock_res *lockres = NULL;
	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
	struct buffer_head *local_bh = NULL;

	BUG_ON(!inode);

	mlog_entry_void();

	mlog(0, "inode %llu, take %s META lock\n",
	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
	     ex ? "EXMODE" : "PRMODE");

	status = 0;
	acquired = 0;
	/* We'll allow faking a readonly metadata lock for
	 * rodevices. */
	if (ocfs2_is_hard_readonly(osb)) {
		if (ex)
			status = -EROFS;
		goto bail;
	}

	if (ocfs2_mount_local(osb))
		goto local;

	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
		wait_event(osb->recovery_event,
			   ocfs2_node_map_is_empty(osb, &osb->recovery_map));

	lockres = &OCFS2_I(inode)->ip_meta_lockres;
	level = ex ? LKM_EXMODE : LKM_PRMODE;
	dlm_flags = 0;
	if (arg_flags & OCFS2_META_LOCK_NOQUEUE)
		dlm_flags |= LKM_NOQUEUE;

	status = ocfs2_cluster_lock(osb, lockres, level, dlm_flags, arg_flags);
	if (status < 0) {
		if (status != -EAGAIN && status != -EIOCBRETRY)
			mlog_errno(status);
		goto bail;
	}

	/* Notify the error cleanup path to drop the cluster lock. */
	acquired = 1;

	/* We wait twice because a node may have died while we were in
	 * the lower dlm layers. The second time though, we've
	 * committed to owning this lock so we don't allow signals to
	 * abort the operation. */
	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
		wait_event(osb->recovery_event,
			   ocfs2_node_map_is_empty(osb, &osb->recovery_map));

local:
	/*
	 * We only see this flag if we're being called from
	 * ocfs2_read_locked_inode(). It means we're locking an inode
	 * which hasn't been populated yet, so clear the refresh flag
	 * and let the caller handle it.
	 */
	if (inode->i_state & I_NEW) {
		status = 0;
		if (lockres)
			ocfs2_complete_lock_res_refresh(lockres, 0);
		goto bail;
	}

	/* This is fun. The caller may want a bh back, or it may
	 * not. ocfs2_meta_lock_update definitely wants one in, but
	 * may or may not read one, depending on what's in the
	 * LVB. The result of all of this is that we've *only* gone to
	 * disk if we have to, so the complexity is worthwhile. */
	status = ocfs2_meta_lock_update(inode, &local_bh);
	if (status < 0) {
		if (status != -ENOENT)
			mlog_errno(status);
		goto bail;
	}

	if (ret_bh) {
		status = ocfs2_assign_bh(inode, ret_bh, local_bh);
		if (status < 0) {
			mlog_errno(status);
			goto bail;
		}
	}

bail:
	if (status < 0) {
		if (ret_bh && (*ret_bh)) {
			brelse(*ret_bh);
			*ret_bh = NULL;
		}
		if (acquired)
			ocfs2_meta_unlock(inode, ex);
	}

	if (local_bh)
		brelse(local_bh);

	mlog_exit(status);
	return status;
}

/*
 * This is working around a lock inversion between tasks acquiring DLM locks
 * while holding a page lock and the vote thread which blocks dlm lock acquiry
 * while acquiring page locks.
 *
 * ** These _with_page variantes are only intended to be called from aop
 * methods that hold page locks and return a very specific *positive* error
 * code that aop methods pass up to the VFS -- test for errors with != 0. **
 *
 * The DLM is called such that it returns -EAGAIN if it would have blocked
 * waiting for the vote thread.  In that case we unlock our page so the vote
 * thread can make progress.  Once we've done this we have to return
 * AOP_TRUNCATED_PAGE so the aop method that called us can bubble that back up
 * into the VFS who will then immediately retry the aop call.
 *
 * We do a blocking lock and immediate unlock before returning, though, so that
 * the lock has a great chance of being cached on this node by the time the VFS
 * calls back to retry the aop.    This has a potential to livelock as nodes
 * ping locks back and forth, but that's a risk we're willing to take to avoid
 * the lock inversion simply.
 */
int ocfs2_meta_lock_with_page(struct inode *inode,
			      struct buffer_head **ret_bh,
			      int ex,
			      struct page *page)
{
	int ret;

	ret = ocfs2_meta_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);
	if (ret == -EAGAIN) {
		unlock_page(page);
		if (ocfs2_meta_lock(inode, ret_bh, ex) == 0)
			ocfs2_meta_unlock(inode, ex);
		ret = AOP_TRUNCATED_PAGE;
	}

	return ret;
}

int ocfs2_meta_lock_atime(struct inode *inode,
			  struct vfsmount *vfsmnt,
			  int *level)
{
	int ret;

	mlog_entry_void();
	ret = ocfs2_meta_lock(inode, NULL, 0);
	if (ret < 0) {
		mlog_errno(ret);
		return ret;
	}

	/*
	 * If we should update atime, we will get EX lock,
	 * otherwise we just get PR lock.
	 */
	if (ocfs2_should_update_atime(inode, vfsmnt)) {
		struct buffer_head *bh = NULL;

		ocfs2_meta_unlock(inode, 0);
		ret = ocfs2_meta_lock(inode, &bh, 1);
		if (ret < 0) {
			mlog_errno(ret);
			return ret;
		}
		*level = 1;
		if (ocfs2_should_update_atime(inode, vfsmnt))
			ocfs2_update_inode_atime(inode, bh);
		if (bh)
			brelse(bh);
	} else
		*level = 0;

	mlog_exit(ret);
	return ret;
}

void ocfs2_meta_unlock(struct inode *inode,
		       int ex)
{
	int level = ex ? LKM_EXMODE : LKM_PRMODE;
	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_meta_lockres;
	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

	mlog_entry_void();

	mlog(0, "inode %llu drop %s META lock\n",
	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
	     ex ? "EXMODE" : "PRMODE");

	if (!ocfs2_is_hard_readonly(OCFS2_SB(inode->i_sb)) &&
	    !ocfs2_mount_local(osb))
		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres, level);

	mlog_exit_void();
}

int ocfs2_super_lock(struct ocfs2_super *osb,
		     int ex)
{
	int status = 0;
	int level = ex ? LKM_EXMODE : LKM_PRMODE;
	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
	struct buffer_head *bh;
	struct ocfs2_slot_info *si = osb->slot_info;

	mlog_entry_void();

	if (ocfs2_is_hard_readonly(osb))
		return -EROFS;

	if (ocfs2_mount_local(osb))
		goto bail;

	status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}

	/* The super block lock path is really in the best position to
	 * know when resources covered by the lock need to be
	 * refreshed, so we do it here. Of course, making sense of
	 * everything is up to the caller :) */
	status = ocfs2_should_refresh_lock_res(lockres);
	if (status < 0) {
		mlog_errno(status);
		goto bail;
	}
	if (status) {
		bh = si->si_bh;