Lachlan McIlroy wrote:
> Eric Sandeen wrote:
>> Eric Sandeen wrote:
>>
>>> Gah; or not. what is going on here... Doing just steps 1, 2, 3, 4
>>> (ending on the extending truncate):
>>>
>>> # xfs_io -c "pwrite -S 0x11 -b 4096 0 4096" -c "mmap -r 0 512" -c "mread
>>> 0 512" -c "munmap" -c "truncate 256" -c "truncate 514" -t -d -f
>>> /mnt/scratch/testfile
>>>
>>> # xfs_bmap -v /mnt/scratch/testfile
>>> /mnt/scratch/testfile:
>>> EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL
>>> 0: [0..0]: 63..63 0 (63..63) 1
>>> 1: [1..1]: hole 1
>>>
>>> It looks like what I expect, at this point. But then:
>>>
>>> # sync
>>> # xfs_bmap -v /mnt/scratch/testfile
>>> /mnt/scratch/testfile:
>>> EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL
>>> 0: [0..1]: 63..64 0 (63..64) 2
>>>
>>> Um, why'd that last block get mapped in? mmap vs. direct IO I'm
>>> guessing... w/o the mmap read this does not happen.
>> Replying to myself twice? I really need to go to bed.
>>
>> So this all does seem to come back to page_state_convert.
>>
>> Both the extending write in the original case and the sync above find
>> their way there; but esp. in the sync test above, why do we have *any*
>> work to do?
> Eric, did you find out why sync was allocating that second block?
I'm afraid this has been on the back burner (or maybe further back) for
a while... so... either "no" or "I don't remember" :)
-Eric
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