fs/udf: vm pages "overlap" while reading large dir [patch]

[Andriy Gapon]

on 04/02/2008 22:07 Pav Lucistnik said the following:
> Julian Elischer píše v po 04. 02. 2008 v 10:36 -0800:
>> Andriy Gapon wrote:
>>> More on the problem with reading big directories on UDF.
>> You do realise that you have now made yourself the official
>> maintainer of the UDF file system by submitting a competent
>> and insightful analysis of the problem?
> 
> Yay, and can you fix the sequential read performance while you're at it?
> Kthx!
> 

Pav,

this was almost trivial :-)
See the attached patch, first hunk is just for consistency.
The code was borrowed from cd9660, only field/variable names are adjusted.

But there is another issue that I also mentioned in the email about
directory reading. It is UDF_INVALID_BMAP case of udf_bmap_internal,
i.e. the case when file data is embedded into a file entry.
This is a special case that needs to be handled differently.
udf_readatoffset() handles it, but the latest udf_read code doesn't.
I have a real UDF filesystem where this type of allocation is used for
small files and those files can not be read.

This is described in Part 4, section 14.6.8 of ECMA-167.

-- 
Andriy Gapon
-------------- next part --------------
A non-text attachment was scrubbed...
Name: udf_ra.patch
Type: text/x-patch
Size: 1633 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-hackers/attachments/20080205/ff86a279/udf_ra.bin