Vincent Legoll 写道：
> I think the filesystem (or directory) is full of inodes.

No, but it's a similar hard limit, and one that not even ‘df -i’ 
will warn you about.

Ext4's dir_index feature uses hash tables to look up directory 
entries, so that for directories with a very large number of items 
(like /gnu/store!), the kernel doesn't have to do the horribly 
slow equivalent of:

  for i in *; do …; done

Unfortunately, once that hash table fills up, the premier stable 
Linux file system just… gives up and refuses to write any more 
data.  In a very cryptic way.

The large_dir flag ‘increases the limit’ (the man page does not 
say by how much) but it doesn't go away.

Your hash table is full of eels,

T G-R