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List:       reiserfs-devel
Subject:    (reiserfs) Re: Is this bad?
From:       "Stephen C. Tweedie" <sct () redhat ! com>
Date:       1999-02-10 16:24:02
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Hi,

On Wed, 10 Feb 1999 17:59:21 +0300, "Vladimir V. Saveliev"
<vs@namesys.botik.ru> said:

> bmap moves unaligned drops to new allocated data block, adds its block
> number to the tree and returns that block number.  We call this
> direct_to_indirect conversion.

Ouch.  grep() uses mmap(), and so any grep over a small-file directory
is going to be really expensive.

I think you probably need to define your own readpage() inode operation,
and special case that to read directly from the drop if you are in the
tail of the file.  Your custom readpage() function can simply call
generic_readpage() for all other cases.

You can still support dynamic relocation for bmap(), but using your own
readpage will prevent the bmap from being called in that case.

Or do you already do this?  Hit me hard if so. :)

--Stephen

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