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Hi all,
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<div>It seems guestmount always fails to flush changes to the mounted qcow2 snapshot.</div>
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<div>To reproduce this problem:</div>
<div>1. take an external snapshot for a qcow2</div>
<div>2. guestmount the snapshot</div>
<div>3. do some changes, for example: <span style="font-size: 10.5pt; line-height: 1.5; background-color: window;">`echo 123 > /test; cat /test`, </span><span style="font-size: 10.5pt; line-height: 1.5; background-color: window;">right now /test can be seen
created and containing the right content</span></div>
<div>4. fusermount -u {mount-point}</div>
<div>5. virt-cat changed file, for the example above, sometimes /test doesn't exist, sometimes /test does exist but has no content</div>
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<div>My libguestfs version is <span style="background-color: rgba(0, 0, 0, 0); font-size: 10.5pt; line-height: 1.5;">1.20.11, and it's running on CentOS 6.6.</span></div>
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<div>I tried several ways to work this around, but none of them worked.</div>
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<div>I suspect it's a cache problem, so I tried to wait a while before umounting the image, sometimes this way works, sometimes it doesn't.</div>
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<div>I also looked into the documentation for syncing and caching options, I tried to mount the image with fuse options like:</div>
<div><span style="color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">guestmount -o direct_io -o sync -o sync_read -o big_writes -w</span></div>
<div>no luck either.</div>
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<div>What could be the cause? Is mounting a snapshot a problem?</div>
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<div>Thanks.</div>
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