[PATCH v4 4/9] xfsrestore: mmap dirent names for faster lookups

[Bill Kendall]

On 11/23/2010 07:48 AM, Christoph Hellwig wrote:
> On Fri, Nov 19, 2010 at 12:38:37PM -0600, Bill Kendall wrote:
>> Pathname resolution in xfsrestore is about 4x faster if the file
>> containing dirent names ("namreg") is memory mapped.  If xfsrestore is
>> unable to map the file (e.g., due to virtual memory constraints)
>> fallback to the existing seek-and-read approach.
>>
>> The file is mapped after all directory entries have been written to
>> the "namreg" file. If the caller tries to add additional entries after
>> the file has been mapped, it will be unmapped and restore will resort
>> back to seek-and-read lookups.
>
> This looks much simpler indeed.  Is it intentional that the namreg file
> is never unmapped any more?

There are several modules in xfsrestore which map files. None of them
currently contain a destructor/cleanup function for unmapping the files.
It would be a good change to make though.

Bill