reddir-ahead: Fix EOD propagation problem

In readdirp fop, op_errno is overloaded to indicate the EOD detection.
If op_errno contains ENOENT, then it indicates that there are no
further entries pending read in the directory. Currently NFS uses the
ENOENT to identify the EOD.

Issue:
NFS clients issues a 4K buffer for readdirp, readdir-ahead converts it
to 128K buffer as its reading ahead. If there are 100 entries in the
bricks, 128K can get all 100 and store in readdir-ahead, but only 23
entries that can be fit in 4K will be sent to NFS. Since the whole
100 entries were read from brick, the op_errno is set to ENOENT, and
the op_errno is propagated as is when sent to NFS. Hence NFS client
in reading 23 entries thinks it reached EOD.

Solution:
Do not propogate ENOENT errno, unless all the entries are read
from the readdir ahead buffer.

> Reviewed-on: https://review.gluster.org/16953
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> (cherry picked from commit 61f76f318faed395660f5bbcfe39616b39c158f0)

Change-Id: I4f173a77b21ab9e98ae35e291a45b8fc0cde65bd
BUG: 1439148
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: https://review.gluster.org/17001
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

0 files changed, 0 insertions, 0 deletions