inode.c

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 *
 * We no longer cache the sb_flags in i_flags - see fs.h
 *	-- [e-mail]
 */
static struct inode * get_new_inode(struct super_block *sb, unsigned long ino, struct list_head *head, find_inode_t find_actor, void *opaque)
{
	struct inode * inode;

	inode = alloc_inode();
	if (inode) {
		struct inode * old;

		spin_lock(&inode_lock);
		/* We released the lock, so.. */
		old = find_inode(sb, ino, head, find_actor, opaque);
		if (!old) {
			inodes_stat.nr_inodes++;
			list_add(&inode->i_list, &inode_in_use);
			list_add(&inode->i_hash, head);
			inode->i_sb = sb;
			inode->i_dev = sb->s_dev;
			inode->i_blkbits = sb->s_blocksize_bits;
			inode->i_ino = ino;
			inode->i_flags = 0;
			atomic_set(&inode->i_count, 1);
			inode->i_state = I_LOCK;
			spin_unlock(&inode_lock);

			clean_inode(inode);

			/* reiserfs specific hack right here.  We don't
			** want this to last, and are looking for VFS changes
			** that will allow us to get rid of it.
			** -- [e-mail] 
			*/
			if (sb->s_op->read_inode2) {
				sb->s_op->read_inode2(inode, opaque) ;
			} else {
				sb->s_op->read_inode(inode);
			}

			/*
			 * This is special!  We do not need the spinlock
			 * when clearing I_LOCK, because we're guaranteed
			 * that nobody else tries to do anything about the
			 * state of the inode when it is locked, as we
			 * just created it (so there can be no old holders
			 * that haven't tested I_LOCK).
			 */
			inode->i_state &= ~I_LOCK;
			wake_up(&inode->i_wait);

			return inode;
		}

		/*
		 * Uhhuh, somebody else created the same inode under
		 * us. Use the old inode instead of the one we just
		 * allocated.
		 */
		__iget(old);
		spin_unlock(&inode_lock);
		destroy_inode(inode);
		inode = old;
		wait_on_inode(inode);
	}
	return inode;
}

static inline unsigned long hash(struct super_block *sb, unsigned long i_ino)
{
	unsigned long tmp = i_ino + ((unsigned long) sb / L1_CACHE_BYTES);
	tmp = tmp + (tmp >> I_HASHBITS);
	return tmp & I_HASHMASK;
}

/* Yeah, I know about quadratic hash. Maybe, later. */

/**
 *	iunique - get a unique inode number
 *	@sb: superblock
 *	@max_reserved: highest reserved inode number
 *
 *	Obtain an inode number that is unique on the system for a given
 *	superblock. This is used by file systems that have no natural
 *	permanent inode numbering system. An inode number is returned that
 *	is higher than the reserved limit but unique.
 *
 *	BUGS:
 *	With a large number of inodes live on the file system this function
 *	currently becomes quite slow.
 */
 
ino_t iunique(struct super_block *sb, ino_t max_reserved)
{
	static ino_t counter = 0;
	struct inode *inode;
	struct list_head * head;
	ino_t res;
	spin_lock(&inode_lock);
retry:
	if (counter > max_reserved) {
		head = inode_hashtable + hash(sb,counter);
		inode = find_inode(sb, res = counter++, head, NULL, NULL);
		if (!inode) {
			spin_unlock(&inode_lock);
			return res;
		}
	} else {
		counter = max_reserved + 1;
	}
	goto retry;
	
}

struct inode *igrab(struct inode *inode)
{
	spin_lock(&inode_lock);
	if (!(inode->i_state & I_FREEING))
		__iget(inode);
	else
		/*
		 * Handle the case where s_op->clear_inode is not been
		 * called yet, and somebody is calling igrab
		 * while the inode is getting freed.
		 */
		inode = NULL;
	spin_unlock(&inode_lock);
	return inode;
}


struct inode *iget4(struct super_block *sb, unsigned long ino, find_inode_t find_actor, void *opaque)
{
	struct list_head * head = inode_hashtable + hash(sb,ino);
	struct inode * inode;

	spin_lock(&inode_lock);
	inode = find_inode(sb, ino, head, find_actor, opaque);
	if (inode) {
		__iget(inode);
		spin_unlock(&inode_lock);
		wait_on_inode(inode);
		return inode;
	}
	spin_unlock(&inode_lock);

	/*
	 * get_new_inode() will do the right thing, re-trying the search
	 * in case it had to block at any point.
	 */
	return get_new_inode(sb, ino, head, find_actor, opaque);
}

/**
 *	insert_inode_hash - hash an inode
 *	@inode: unhashed inode
 *
 *	Add an inode to the inode hash for this superblock. If the inode
 *	has no superblock it is added to a separate anonymous chain.
 */
 
void insert_inode_hash(struct inode *inode)
{
	struct list_head *head = &anon_hash_chain;
	if (inode->i_sb)
		head = inode_hashtable + hash(inode->i_sb, inode->i_ino);
	spin_lock(&inode_lock);
	list_add(&inode->i_hash, head);
	spin_unlock(&inode_lock);
}

/**
 *	remove_inode_hash - remove an inode from the hash
 *	@inode: inode to unhash
 *
 *	Remove an inode from the superblock or anonymous hash.
 */
 
void remove_inode_hash(struct inode *inode)
{
	spin_lock(&inode_lock);
	list_del(&inode->i_hash);
	INIT_LIST_HEAD(&inode->i_hash);
	spin_unlock(&inode_lock);
}

/**
 *	iput	- put an inode 
 *	@inode: inode to put
 *
 *	Puts an inode, dropping its usage count. If the inode use count hits
 *	zero the inode is also then freed and may be destroyed.
 */
 
void iput(struct inode *inode)
{
	if (inode) {
		struct super_block *sb = inode->i_sb;
		struct super_operations *op = NULL;

		if (inode->i_state == I_CLEAR)
			BUG();

		if (sb && sb->s_op)
			op = sb->s_op;
		if (op && op->put_inode)
			op->put_inode(inode);

		if (!atomic_dec_and_lock(&inode->i_count, &inode_lock))
			return;

		if (!inode->i_nlink) {
			list_del(&inode->i_hash);
			INIT_LIST_HEAD(&inode->i_hash);
			list_del(&inode->i_list);
			INIT_LIST_HEAD(&inode->i_list);
			inode->i_state|=I_FREEING;
			inodes_stat.nr_inodes--;
			spin_unlock(&inode_lock);

			if (inode->i_data.nrpages)
				truncate_inode_pages(&inode->i_data, 0);

			if (op && op->delete_inode) {
				void (*delete)(struct inode *) = op->delete_inode;
				if (!is_bad_inode(inode))
					DQUOT_INIT(inode);
				/* s_op->delete_inode internally recalls clear_inode() */
				delete(inode);
			} else
				clear_inode(inode);
			if (inode->i_state != I_CLEAR)
				BUG();
		} else {
			if (!list_empty(&inode->i_hash)) {
				if (!(inode->i_state & (I_DIRTY|I_LOCK))) {
					list_del(&inode->i_list);
					list_add(&inode->i_list, &inode_unused);
				}
				inodes_stat.nr_unused++;
				spin_unlock(&inode_lock);
				if (!sb || (sb->s_flags & MS_ACTIVE))
					return;
				write_inode_now(inode, 1);
				spin_lock(&inode_lock);
				inodes_stat.nr_unused--;
				list_del_init(&inode->i_hash);
			}
			list_del_init(&inode->i_list);
			inode->i_state|=I_FREEING;
			inodes_stat.nr_inodes--;
			spin_unlock(&inode_lock);
			if (inode->i_data.nrpages)
				truncate_inode_pages(&inode->i_data, 0);
			clear_inode(inode);
		}
		destroy_inode(inode);
	}
}

void force_delete(struct inode *inode)
{
	/*
	 * Kill off unused inodes ... iput() will unhash and
	 * delete the inode if we set i_nlink to zero.
	 */
	if (atomic_read(&inode->i_count) == 1)
		inode->i_nlink = 0;
}

/**
 *	bmap	- find a block number in a file
 *	@inode: inode of file
 *	@block: block to find
 *
 *	Returns the block number on the device holding the inode that
 *	is the disk block number for the block of the file requested.
 *	That is, asked for block 4 of inode 1 the function will return the
 *	disk block relative to the disk start that holds that block of the 
 *	file.
 */
 
int bmap(struct inode * inode, int block)
{
	int res = 0;
	if (inode->i_mapping->a_ops->bmap)
		res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
	return res;
}

/*
 * Initialize the hash tables.
 */
void __init inode_init(unsigned long mempages)
{
	struct list_head *head;
	unsigned long order;
	unsigned int nr_hash;
	int i;

	mempages >>= (14 - PAGE_SHIFT);
	mempages *= sizeof(struct list_head);
	for (order = 0; ((1UL << order) << PAGE_SHIFT) < mempages; order++)
		;

	do {
		unsigned long tmp;

		nr_hash = (1UL << order) * PAGE_SIZE /
			sizeof(struct list_head);
		i_hash_mask = (nr_hash - 1);

		tmp = nr_hash;
		i_hash_shift = 0;
		while ((tmp >>= 1UL) != 0UL)
			i_hash_shift++;

		inode_hashtable = (struct list_head *)
			__get_free_pages(GFP_ATOMIC, order);
	} while (inode_hashtable == NULL && --order >= 0);

	printk("Inode-cache hash table entries: %d (order: %ld, %ld bytes)\n",
			nr_hash, order, (PAGE_SIZE << order));

	if (!inode_hashtable)
		panic("Failed to allocate inode hash table\n");

	head = inode_hashtable;
	i = nr_hash;
	do {
		INIT_LIST_HEAD(head);
		head++;
		i--;
	} while (i);

	/* inode slab cache */
	inode_cachep = kmem_cache_create("inode_cache", sizeof(struct inode),
					 0, SLAB_HWCACHE_ALIGN, init_once,
					 NULL);
	if (!inode_cachep)
		panic("cannot create inode slab cache");

	unused_inodes_flush_task.routine = try_to_sync_unused_inodes;
}

/**
 *	update_atime	-	update the access time
 *	@inode: inode accessed
 *
 *	Update the accessed time on an inode and mark it for writeback.
 *	This function automatically handles read only file systems and media,
 *	as well as the "noatime" flag and inode specific "noatime" markers.
 */
 
void update_atime (struct inode *inode)
{
	if (inode->i_atime == CURRENT_TIME)
		return;
	if ( IS_NOATIME (inode) ) return;
	if ( IS_NODIRATIME (inode) && S_ISDIR (inode->i_mode) ) return;
	if ( IS_RDONLY (inode) ) return;
	inode->i_atime = CURRENT_TIME;
	mark_inode_dirty_sync (inode);
}   /*  End Function update_atime  */


/*
 *	Quota functions that want to walk the inode lists..
 */
#ifdef CONFIG_QUOTA

/* Functions back in dquot.c */
void put_dquot_list(struct list_head *);
int remove_inode_dquot_ref(struct inode *, short, struct list_head *);

void remove_dquot_ref(struct super_block *sb, short type)
{
	struct inode *inode;
	struct list_head *act_head;
	LIST_HEAD(tofree_head);

	if (!sb->dq_op)
		return;	/* nothing to do */
	/* We have to be protected against other CPUs */
	lock_kernel();		/* This lock is for quota code */
	spin_lock(&inode_lock);	/* This lock is for inodes code */
 
	list_for_each(act_head, &inode_in_use) {
		inode = list_entry(act_head, struct inode, i_list);
		if (inode->i_sb == sb && IS_QUOTAINIT(inode))
			remove_inode_dquot_ref(inode, type, &tofree_head);
	}
	list_for_each(act_head, &inode_unused) {
		inode = list_entry(act_head, struct inode, i_list);
		if (inode->i_sb == sb && IS_QUOTAINIT(inode))
			remove_inode_dquot_ref(inode, type, &tofree_head);
	}
	list_for_each(act_head, &sb->s_dirty) {
		inode = list_entry(act_head, struct inode, i_list);
		if (IS_QUOTAINIT(inode))
			remove_inode_dquot_ref(inode, type, &tofree_head);
	}
	list_for_each(act_head, &sb->s_locked_inodes) {
		inode = list_entry(act_head, struct inode, i_list);
		if (IS_QUOTAINIT(inode))
			remove_inode_dquot_ref(inode, type, &tofree_head);
	}
	spin_unlock(&inode_lock);
	unlock_kernel();

	put_dquot_list(&tofree_head);
}

#endif