virtiofs: fallocate: should enlarge but not shrink the file #203
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djs55
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crobinso,
mtjhrc,
slp and
tylerfanelli
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p1-0tr
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Jun 24, 2024
Before this patch on virtiofs we had: ``` $ fallocate -o 0 -l 1024 f $ ls -l f -rw-r--r-- 1 root root 1024 Jun 24 13:00 f $ fallocate -o 0 -l 512 f $ ls -l f -rw-r--r-- 1 root root 512 Jun 24 13:00 f ``` Unfortunately the second `fallocate` call caused the file to shrink, due to the call to `ftruncate`. On a tmpfs for comparison the file doesn't shrink: ``` $ fallocate -o 0 -l 1024 f $ ls -l f -rw-r--r-- 1 root root 1024 Jun 24 12:55 f $ fallocate -o 0 -l 512 f $ ls -l f -rw-r--r-- 1 root root 1024 Jun 24 12:56 f ``` This patch only calls ftuncate() if the proposed_length is larger than the current length. Signed-off-by: David Scott <dave@recoil.org>
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Before this patch on virtiofs we had:
Unfortunately the second
fallocatecall caused the file to shrink, due to the call toftruncate.On a tmpfs for comparison the file doesn't shrink:
This patch only calls ftuncate() if the proposed_length is larger than the current length.