Suggestion: bmap files and bmaptool

Artem Bityutskiy dedekind1 at
Tue Sep 17 13:39:40 UTC 2013

On Sun, 2013-08-18 at 16:43 +0100, Pádraig Brady wrote:
> You definitely need the fsync before doing the fiemap.
> We saw this on certain file systems including ext4 when adding
> fiemap support (efficient reading of holes) to cp.
> This is a bug in the fiemap interface IMHO in that it returns
> fairly useless data unless FIEMAP_FLAG_SYNC is specified.
> For a general utility like cp, we couldn't sync each file before copying
> (even only large files), so we restrict fiemap usage to files that
> have a different disk usage than apparent size and so probably contain holes.

FYI, I've just made sure I use the FIEMAP_FLAG_SYNC is used in the

Best Regards,
Artem Bityutskiy

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