nfs: opendir/closedir for every readdir

Revert "nfs3: Unref & unbind dir fd with inode lock on EOF"

This reverts commit 4e6fb304ce41acbaf7c9ba67c06bf443e65082e8.

The above commit (which unbinds fds at EOF) does not fix the original
bug (1619) because a readdir from a second app could have already
started before the readdir_cbk of the first app's readdir reaches
NFS code. Hence the race still exists.

Performing extra unrefs when EOF is received is not a reliable way
of detecting that a client has performed a closedir (and to close
the fd ourselves). Neither is interpreting a 0 cookies a new opendir.
Clients can always use telldir/seekdir and hit EOFs twice.

Due to the way NFS3 protocol is designed, it is just not possible
for the server to reliably detect opendirs/closedirs performed by
the client and map the corresponding readdirs to the same dir fd
on the server side.

The only reliable way of fixing this is to perform opendir/closedir
at the cost of performance. Any optimization towards keeping dir fds
open attempting to map them with application's opendir/closedir will
either result in fd leaks or extra fd unrefs.

Signed-off-by: Anand V. Avati <avati@blackhole.gluster.com>
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 2061 (NFS server crashes in readdir_fstat_cbk due to extra fd unref)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=2061

0 files changed, 0 insertions, 0 deletions