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| From: | Eric Sandeen |
| Subject: | Re: Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?) |
| Date: | Mon, 18 Apr 2011 22:05:15 -0500 |
| User-agent: | Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 |
On 4/18/11 9:59 PM, Ted Ts'o wrote: ... > Maybe coreutils will need to use FIEMAP_FLAG_SYNC initially, since > it's the only way to guarantee correct behaviour for XFS. But I would > really rather that be the long-term way we leave things! XFS ... or ext4: # xfs_io -Ff -c "falloc 0 1m" -c "pwrite 0 512k" testfile; /root/fiemap-test testfile wrote 524288/524288 bytes at offset 0 512 KiB, 128 ops; 0.0000 sec (161.342 MiB/sec and 41303.6463 ops/sec) start 0 length -1 flags 0x0 count 32 ext: 0 logical: [ 0.. 255] phys: 34048.. 34303 flags: 0x801 tot: 256 # uname -r 2.6.39-0.rc3.git2.0.fc16.x86_64 Above is on ext4. It behaves exactly like XFS in my testing; data in the page cache does not cause fiemap to return anything other than "unwritten" for preallocated extents. -Eric
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