Messages in this thread | | | Date | Fri, 11 Jun 2010 10:15:10 +0800 | From | Tao Ma <> | Subject | fiemap is broken for sparse file in ext4? |
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Hi Ted and other ext4 gurus, I found fiemap may be broken for sparse files in ext4. Here is a simple example.
dd if=/dev/zero of=testfile1 bs=1M count=1 using fiemap shows that it has a delalloc extent. Logical: 0 Ext length: 1048576 Physical: 0 flags: 7
flags 7 means FIEMAP_EXTENT_LAST, FIEMAP_EXTENT_UNKNOWN and FIEMAP_EXTENT_DELALLOC,
while if we create a sparse file, fiemap will not show the delalloc extent. dd if=/dev/zero of=testfile1 bs=1M count=1 seek=1 using fiemap shows that it has no extent for the file. while we should have some output like: Logical: 1048576 Ext length: 1048576 Physical: 0 flags: 7
So we have different output with sparse and non-sparse file. Is it a bug for ext4?
Regards, Tao
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