Re: [PATCH] ext34: ensure do_split leaves enough free space in both blocks

[Eric Sandeen <sandeen@sandeen.net>]

Eric Sandeen wrote:
> The do_split() function for htree dir blocks is intended to split a
> leaf block to make room for a new entry.  It sorts the entries in the
> original block by hash value, then moves the last half of the entries to 
> the new block - without accounting for how much space this actually moves.  
> (IOW, it moves half of the entry *count* not half of the entry *space*).
> If by chance we have both large & small entries, and we move only the 
> smallest entries, and we have a large new entry to insert, we may not have 
> created enough space for it.

(btw, the upshot of this is that in add_dirent_to_buf(),
memcpy(de->name, name, namelen) will overshoot the buffer and actually
corrupt memory.)

:(

-Eric