Loss of data on copy to full partition

[onlyjob]

To reproduce:

1. Copy file(s) to ext4 partition until there is no more free space left.
2. When no more space left choose small file around 7K in size and try to copy it.
3. When dialog "No space left on device (28)" appears, choose "Skip".
4. The same dialog may appear again - choose "Skip" one more time.
5. Observe empty (zero-size) file being created in destination.

If copying many files to partition with no free space, choosing "Skip All" may lead to weird condition when copying seemingly continue after filling all the space in partition but leaving zero-size files behind. (Consequences of move may be devastating)

Another manifestation of this problem is when you're editing the file on full partition with mcedit and add text to the beginning of file it may be trimmed to 4096 bytes and loose its tail on save.

See

​http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=677038
​http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=677309

Please advise.

[andrew_b]

Replying to onlyjob:

Another manifestation of this problem is when you're editing the file on full partition with mcedit and add text to the beginning of file it may be trimmed to 4096 bytes and loose its tail on save.

​http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=677309

This is another bug that isn't related with copy/move file operation. See #2470 and #15.

[onlyjob]

I see, thank you (somehow I didn't know about mcedit' save modes).

To avoid reporting two issues as one I should be better searching for corresponding ticket next time.

Cheers,
Dmitry.

[andrew_b]

Branch: 2829_copy_to_full_partition (parent: master).
changeset:6c59cff328bc0728cd9a4105b9b19bfd397422e8

[onlyjob]

Thanks for the patch.
I tried it and here is some feedback:

When copying one file to full partition a dialog "No space left on device (28)" appears.

If I choose [Skip] the same dialog returns (as if I choose [Retry]);

[Skip All] or [Abort] lead to another dialog "Incomplete file retrieved. Keep it?"

When copying many files [Skip] also behaves like [Retry].

But the most unexpected thing happened when I tried to copy small file just about 12 KB:
first dialog "Cannot write target file... No space left on device (28)" appears
but when I choose [Skip] few times either empty file is created in destination
or (if I'm overwriting existing file) target file is trimmed down to exactly 4096 bytes.

[andrew_b]

Replying to onlyjob:

Thanks for the patch.
I tried it and here is some feedback:
[...]

Thanks for the feedback!

I don't have an unallocated free space on my hard drive to create small partition and test with it. But I tested my patch with two ways:
a) I created a small partition in the file and mount that via loop device;
b) I installed Linux in VirtualBox? and created small partition within that.

Unfortunately, I'm unable to reproduce and confirm none of you feedback issues.

When copying one file to full partition a dialog "No space left on device (28)" appears.

If I choose [Skip] the same dialog returns (as if I choose [Retry]);

Works as expected for me. "No space left on device (28)" error isn't appears again.

[Skip All] or [Abort] lead to another dialog "Incomplete file retrieved. Keep it?"

Cannot confirm.

When copying many files [Skip] also behaves like [Retry].

But the most unexpected thing happened when I tried to copy small file just about 12 KB:
first dialog "Cannot write target file... No space left on device (28)" appears
but when I choose [Skip] few times either empty file is created in destination
or (if I'm overwriting existing file) target file is trimmed down to exactly 4096 bytes.

Cannot confirm too.

[onlyjob]

Replying to andrew_b:

a) I created a small partition in the file and mount that via loop device;

That's what I did as well. I used ext4 partition of 80M.

Unfortunately, I'm unable to reproduce and confirm none of you feedback issues.

Perhaps we're doing something in a different way. I noticed that some of the problems getting worse when there is no free space in partition whatsoever. If there are few KB still available errors may be harder to reproduce.

Also I was using 3.8.3 with patch I've made of your changeset.

I hope this may be of help.

[andrew_b]

Do you use the "Preallocate space" option (Menu->Options->Configuration->File operation options)?

[onlyjob]

Replying to andrew_b:

Do you use the "Preallocate space" option (Menu->Options->Configuration->File operation options)?

No, it is not in use. Sorry for not mentioning it.

[andrew_b]

OK. I added the tweak commit [fddfb7bf96a2f76c28ac85352b7d96e58fddae21]. Please test it together with [6c59cff328bc0728cd9a4105b9b19bfd397422e8].

[onlyjob]

patch for 4.8.3

[onlyjob]

Andrew, it is perfect. Thank you.
I tested with and without [Preallocate space].

Patch for 4.8.3 is attached.

Fantastic work. :)

[andrew_b]

Thanks for test and feedback. My initial mistake was to use errno regardless of what mc_write() returned. If some function returns success value, it does't changes errno (and doesn't set it to 0). errno should be used if and only if function returns error.

[andrew_b]

Merged to master: [af2fe31ff3ef91759c41378b8667ae61d8204cff].
Merged to 4.8.1-stable: [5737723e7720343a6967e00b83a8330dc2dc34af]