glusterfs.git/tests/basic/open-behind, branch release-8 open-behind: rewrite of internal logic 2020-06-29T12:51:52+00:00 Xavi Hernandez xhernandez@redhat.com 2020-05-12T21:54:54+00:00 80e088be4470d86e5c63750f611a39e487a591b3 There was a critical flaw in the previous implementation of open-behind. When an open is done in the background, it's necessary to take a reference on the fd_t object because once we "fake" the open answer, the fd could be destroyed. However as long as there's a reference, the release function won't be called. So, if the application closes the file descriptor without having actually opened it, there will always remain at least 1 reference, causing a leak. To avoid this problem, the previous implementation didn't take a reference on the fd_t, so there were races where the fd could be destroyed while it was still in use. To fix this, I've implemented a new xlator cbk that gets called from fuse when the application closes a file descriptor. The whole logic of handling background opens have been simplified and it's more efficient now. Only if the fop needs to be delayed until an open completes, a stub is created. Otherwise no memory allocations are needed. Correctly handling the close request while the open is still pending has added a bit of complexity, but overall normal operation is simpler. Change-Id: I6376a5491368e0e1c283cc452849032636261592 Fixes: #1225 Signed-off-by: Xavi Hernandez <xhernandez@redhat.com> 
There was a critical flaw in the previous implementation of open-behind.

When an open is done in the background, it's necessary to take a
reference on the fd_t object because once we "fake" the open answer,
the fd could be destroyed. However as long as there's a reference,
the release function won't be called. So, if the application closes
the file descriptor without having actually opened it, there will
always remain at least 1 reference, causing a leak.

To avoid this problem, the previous implementation didn't take a
reference on the fd_t, so there were races where the fd could be
destroyed while it was still in use.

To fix this, I've implemented a new xlator cbk that gets called from
fuse when the application closes a file descriptor.

The whole logic of handling background opens have been simplified and
it's more efficient now. Only if the fop needs to be delayed until an
open completes, a stub is created. Otherwise no memory allocations are
needed.

Correctly handling the close request while the open is still pending
has added a bit of complexity, but overall normal operation is simpler.

Change-Id: I6376a5491368e0e1c283cc452849032636261592
Fixes: #1225
Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>