接上文：
crash> struct -xo dentry.d_inode ffff8818118002c0
struct dentry {
[ffff8818118002d0] struct inode *d_inode;
}
crash> struct dentry.d_inode ffff8818118002c0
d_inode = 0xffff880c11402cf8
crash> struct inode 0xffff880c11402cf8
struct inode {
i_hash = {
next = 0x0,
pprev = 0xffffc900093d9118
},
i_list = {
next = 0xffff880c11401ae8,
prev = 0xffff880c11b9bda8
},
i_sb_list = {
next = 0xffff880c1188ccd0,------------inode的i_sb_list串起来，形成一个双向循环链表，其链表头可以认为是该inode对应的super_block的s_inodes成员的地址
prev = 0xffff880c11402a98
},
i_dentry = {
next = 0xffff881811800330,
prev = 0xffff881811800330
},
i_ino = ,
i_count = {
counter =
},
i_nlink = ,
i_uid = ,
i_gid = ,
i_rdev = ,
i_version = ,
i_size = ,
i_atime = {
tv_sec = ,
tv_nsec =
},
i_mtime = {
tv_sec = ,
tv_nsec =
},
i_ctime = {
tv_sec = ,
tv_nsec =
},
i_blocks = ,
i_blkbits = ,
i_bytes = ,
i_mode = ,
i_lock = {
raw_lock = {
slock =
}
},
i_mutex = {
count = {
counter =
},
wait_lock = {
raw_lock = {
slock =
}
},
wait_list = {
next = 0xffff880c11402db8,
prev = 0xffff880c11402db8
},
owner = 0x0
},
i_alloc_sem = {
count = ,
wait_lock = {
raw_lock = {
slock =
}
},
wait_list = {
next = 0xffff880c11402de0,
prev = 0xffff880c11402de0
}
},
i_op = 0xffffffff8161fb40 <proc_reg_file_ops+>,
i_fop = 0xffffffff8161fc00 <proc_root_inode_operations+>,
i_sb = 0xffff880c1188cc00,
i_flock = 0x0,
i_mapping = 0xffff880c11402e18,
i_data = {
host = 0xffff880c11402cf8,-----------------------address_space的host是指向inode，而inode的i_data是指向对应的address_space，两者就串起来了。
page_tree = {--------------------radix树，主要管理page的
height = ,
gfp_mask = ,
rnode = 0x0
},
tree_lock = {-----------------树锁
raw_lock = {
slock =
}
},
i_mmap_writable = ,
i_mmap = {
prio_tree_node = 0x0,
index_bits = ,
raw =
},
i_mmap_nonlinear = {
next = 0xffff880c11402e48,
prev = 0xffff880c11402e48
},
i_mmap_lock = {
raw_lock = {
slock =
}
},
truncate_count = ,
nrpages = ,
writeback_index = ,
a_ops = 0xffffffff81fcfde0 <empty_aops.>,
flags = ,
backing_dev_info = 0xffffffff81abfb80 <default_backing_dev_info>,
private_lock = {
raw_lock = {
slock =
}
},
private_list = {
next = 0xffff880c11402e90,
prev = 0xffff880c11402e90
},
assoc_mapping = 0x0
},
i_dquot = {0x0, 0x0},
i_devices = {
next = 0xffff880c11402eb8,
prev = 0xffff880c11402eb8
},
{---------------------------这个是inode的类型描述，一个inode要么是字符设备，要么是块设备，要么是pipe设备，要么都不是
i_pipe = 0x0,
i_bdev = 0x0,
i_cdev = 0x0
},
i_generation = ,
i_fsnotify_mask = ,
i_fsnotify_mark_entries = {
first = 0x0
},
inotify_watches = {
next = 0xffff880c11402ee0,
prev = 0xffff880c11402ee0
},
inotify_mutex = {
count = {
counter =
},
wait_lock = {
raw_lock = {
slock =
}
},
wait_list = {
next = 0xffff880c11402ef8,
prev = 0xffff880c11402ef8
},
owner = 0x0
},
i_state = ,
dirtied_when = ,
i_flags = ,
i_writecount = {
counter =
},
i_security = 0x0,
i_acl = 0xffffffffffffffff,
i_default_acl = 0xffffffffffffffff,
i_private = 0x0
}
每个inode对于所属的文件系统来说，是唯一的。比如有两个硬盘，都是xfs分别挂载到两个挂载点，那么对应的这个文件系统里，inode的内存地址也是唯一的，但是可以和其他文件系统中的i_ino成员可能会相同。
inode和对应的super_block 怎么对应起来呢，inode的i_sb_list串起来，形成一个双向循环链表，其链表头可以认为是该inode对应的super_block的s_inodes成员的地址，我们验证一下：
crash> struct inode 0xffff880c11402cf8
struct inode {
i_hash = {
next = 0x0,
pprev = 0xffffc900093d9118
},
i_list = {
next = 0xffff880c11401ae8,
prev = 0xffff880c11b9bda8
},
i_sb_list = {
next = 0xffff880c1188ccd0,--------对应的地址是ccd0
prev = 0xffff880c11402a98
},
可以看到，该inode对应的i_sb_list是ccd0，而该inode归属的super_block是0xffff880c1188cc00，
crash> struct -xo super_block.s_inodes
struct super_block {
[0xd0] struct list_head s_inodes;
}
crash> px 0xffff880c1188cc00+0xd0
$ = 0xffff880c1188ccd0
两者对得上，是不是很面熟，前面我们看dentry的时候，所有子dentry的d_child成员就形成双向循环链表，嵌入到父dentry的d_subdirs中，内核中类似手法很多。
前面文章描述过dentry，但是看inode中，有一个dentry链表，这个是为啥？难道两者不是一一对应关系么？
事实上，两者真不是一一对应，一个inode可能有多个dentry：
crash> struct inode 0xffff880c11402cf8
struct inode {
i_hash = {
next = 0x0,
pprev = 0xffffc900093d9118
},
i_list = {
next = 0xffff880c11401ae8,
prev = 0xffff880c11b9bda8
},
i_sb_list = {
next = 0xffff880c1188ccd0,
prev = 0xffff880c11402a98
},
i_dentry = {
next = 0xffff881811800330,
prev = 0xffff881811800330
}, crash> struct -xo dentry.d_alias
struct dentry {
[0x70] struct list_head d_alias;
}
crash> px 0xffff881811800330-0x70
$ = 0xffff8818118002c0 crash> struct dentry 0xffff8818118002c0
struct dentry {
d_count = {
counter =
},
d_flags = ,
d_lock = {
raw_lock = {
slock =
}
},
d_mounted = ,
d_inode = 0xffff880c11402cf8,
d_hash = {
next = 0x0,
pprev = 0x0
},
d_parent = 0xffff8818118002c0,
d_name = {
hash = ,
len = ,
name = 0xffff881811800360 "/"
},
对于本例中的根目录来说，一个inode只有一个dentry，但是对于硬链接来说，则肯定有多个dentry，所以inode和dentry是1对多的关系。
又同时可以看到，dentry中的d_alias串起来一个双向循环链表，而这个双向循环链表遍历的时候，可以认为这些dentry对应的inode的 i_dentry 是这个双向循环链表的头。
其实inode还有个很关键常用的成员，就是i_list，根据不同的inode状态，会放入不同的list，但是由于这个成员在3.10内核中已经被i_lru和i_wb_list 来代替了，这个两个成员都会嵌入到
该inode所属的superblock的s_inode_lru 以及i_wb_list中。所以就不放在本文中分析了。
最后，通过files -d dentry的地址 ，可以显示对应的inode和superblock，-p的话，还可以展示在pagecache中的page：
crash> files -d ffff8857a2440b40
DENTRY INODE SUPERBLK TYPE PATH
ffff8857a2440b40 ffff88535be752b0 ffff88013d3a8800 REG /mnt/ZMSS/ZMSSThreadMonitor.log
crash> files -p ffff88535be752b0
INODE NRPAGES
ffff88535be752b0 PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffea0121bbd840 486ef61000 ffff88535be75400 6fffff000c0038 uptodate,dirty,lru,reclaim,swapbacked