The ENOENT part of the problem is fixed in CVS trunk now.
-Phil
b) is a bug. That is coming from a follow up operation (setattr or
getattr) after the truncate that has its permissions checked by the
metadata server. There is a problem there in which if all permission
checks fail on the server side PVFS returns enoent:
https://trac.mcs.anl.gov/projects/pvfs/ticket/104
It shouldn't be too hard to cook up a patch for each of these issues.
I'll look into it.
-Phil
Bart Taylor wrote:
Hey guys, we have run into another odd permissions case.
The problem happens when updating a user's access to a file while it
is still stored in another client's acache. In our test a client does
an ls, their write permissions are removed from another client, and
while the cache entry is still valid they try to overwrite the file.
The result is a truncated file of zero bytes with an ENOENT return
value. The test fails as expected and does not truncate the file if
acache is turned off.
Attached is a bash script that sets up the test for you, but it does
require manually running a couple of commands at the right time on
another client. Our clients are using an acache time out of 30 seconds.
To run:
Client1 - start the bash script and waith for the first prompt (
./perms-update-test.sh myuser mygroup /mnt/pvfs2 )
Client2 - execute an ls in the directory passed to the script ( from
/mnt/pvfs2: ls )
Client1 - wait for the second prompt
Client2 - overwrite the file (echo "text" > file1.txt)
Client1 - check the file size if file1.txt in the output
I also attached a server log that shows the truncate succeeding and
immediately calling setattr which fails. The server logging was turned
on only for the file overwrite.
Should the server be checking the file's permissions before the
truncate happens?
Bart.
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