On 3/5/2024 2:43 AM, Mark Geisert via Cygwin wrote:
On 3/5/2024 12:46 AM, Cedric Blancher via Cygwin wrote:
On Mon, 29 Jan 2024 at 10:46, Mark Geisert via Cygwin
<cygwin@cygwin.com> wrote:
On 1/28/2024 11:56 PM, Mark Geisert via Cygwin wrote:
On 1/28/2024 10:44 PM, Cedric Blancher via Cygwin wrote:
Good morning!
rm -f myfile
touch myfile
/usr/bin/fallocate -v -d -l myfile takes forever with latest Cygwin
3.5
^ length goes here, before filename
I believe you need to
chattr +S myfile
after the 'touch' to make the file sparsifiable.
Also, I'm unsure if '-d' makes sense when initially allocating a sparse
file. If I leave it off, fallocate does the right thing.
I'm separately investigating the 'takes forever' report.
It's taking forever because it's in an infinite loop looking for data
followed by a hole, which is not present in a new file being created.
This is due to the '-d' option being specified. fallocate ought to
diagnose this condition rather than looping forever, but here we are.
It's possible we have an old fallocate from an old util-linux package.
I'll try to investigate this further when I have time.
Any update on this issue?
Thanks for the reminder. I'll check repology to see if we can maybe
support a newer util-linux. No guarantees its fallocate is any better,
but lets first see if it builds at all. Give me a couple days, please.
A newer util-linux package has been uploaded. I find that its fallocate
operates identically to the earlier one for your example. So, to
summarize, when allocating a brand new file:
1) don't specify '-d' option,
2) after creating file with 'touch', do 'chattr +S' on it,
3) using fallocate on the file without step 2 won't sparsify it.
It's easier to see fallocate is working properly by giving it a file
size large enough to make a difference by sparsifying. My testing shows
that specifying '-l 2m' to create a 2MB file makes the file occupy 64
blocks if it's sparsified, 2048 blocks if it isn't. Use 'stat <file>' to
get the block size of the file. 'ls -l' will show 2MB either way.
HTH,
..mark
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