inode节点查找

节点查找，查找是利用前面介绍的hash值进行：

/** * ilookup - search for an inode in the inode cache * @sb:super block of file system to search * @ino:inode number to search for * * Search for the inode @ino in the inode cache, and if the inode is in the * cache, the inode is returned with an incremented reference count. */struct inode *ilookup(struct super_block *sb, unsigned long ino){struct hlist_head *head = inode_hashtable + hash(sb, ino);struct inode *inode;again:spin_lock(&inode_hash_lock);inode = find_inode_fast(sb, head, ino);spin_unlock(&inode_hash_lock);if (inode) {wait_on_inode(inode);if (unlikely(inode_unhashed(inode))) {iput(inode);goto again;}}return inode;}

/** * ilookup5 - search for an inode in the inode cache * @sb:super block of file system to search * @hashval:hash value (usually inode number) to search for * @test:callback used for comparisons between inodes * @data:opaque data pointer to pass to @test * * Search for the inode specified by @hashval and @data in the inode cache, * and if the inode is in the cache, return the inode with an incremented * reference count.  Waits on I_NEW before returning the inode. * returned with an incremented reference count. * * This is a generalized version of ilookup() for file systems where the * inode number is not sufficient for unique identification of an inode. * * Note: @test is called with the inode_hash_lock held, so can't sleep. */struct inode *ilookup5(struct super_block *sb, unsigned long hashval,int (*test)(struct inode *, void *), void *data){struct inode *inode;again:inode = ilookup5_nowait(sb, hashval, test, data);if (inode) {wait_on_inode(inode);if (unlikely(inode_unhashed(inode))) {iput(inode);goto again;}}return inode;}

/** * ilookup5_nowait - search for an inode in the inode cache * @sb:super block of file system to search * @hashval:hash value (usually inode number) to search for * @test:callback used for comparisons between inodes * @data:opaque data pointer to pass to @test * * Search for the inode specified by @hashval and @data in the inode cache. * If the inode is in the cache, the inode is returned with an incremented * reference count. * * Note: I_NEW is not waited upon so you have to be very careful what you do * with the returned inode.  You probably should be using ilookup5() instead. * * Note2: @test is called with the inode_hash_lock held, so can't sleep. */struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,int (*test)(struct inode *, void *), void *data){struct hlist_head *head = inode_hashtable + hash(sb, hashval);struct inode *inode;spin_lock(&inode_hash_lock);inode = find_inode(sb, head, test, data);spin_unlock(&inode_hash_lock);return inode;}EXPORT_SYMBOL(ilookup5_nowait);

/** * find_inode_nowait - find an inode in the inode cache * @sb:super block of file system to search * @hashval:hash value (usually inode number) to search for * @match:callback used for comparisons between inodes * @data:opaque data pointer to pass to @match * * Search for the inode specified by @hashval and @data in the inode * cache, where the helper function @match will return 0 if the inode * does not match, 1 if the inode does match, and -1 if the search * should be stopped.  The @match function must be responsible for * taking the i_lock spin_lock and checking i_state for an inode being * freed or being initialized, and incrementing the reference count * before returning 1.  It also must not sleep, since it is called with * the inode_hash_lock spinlock held. * * This is a even more generalized version of ilookup5() when the * function must never block --- find_inode() can block in * __wait_on_freeing_inode() --- or when the caller can not increment * the reference count because the resulting iput() might cause an * inode eviction.  The tradeoff is that the @match funtion must be * very carefully implemented. */struct inode *find_inode_nowait(struct super_block *sb,unsigned long hashval,int (*match)(struct inode *, unsigned long,     void *),void *data){struct hlist_head *head = inode_hashtable + hash(sb, hashval);struct inode *inode, *ret_inode = NULL;int mval;spin_lock(&inode_hash_lock);hlist_for_each_entry(inode, head, i_hash) {if (inode->i_sb != sb)continue;mval = match(inode, hashval, data);if (mval == 0)continue;if (mval == 1)ret_inode = inode;goto out;}out:spin_unlock(&inode_hash_lock);return ret_inode;}