posix: check file state before continuing with fops

In context of Cloudsync:

 In scenarios where a data modification fop e.g. a write landed in
POSIX thinking that the file is local, while the file was actually
remote, can be dangerous. Ofcourse we don’t want to take inodelk
for every read/write operation to check the archival status or
coordinate with an upload or a  download of a file. To avoid inodelk,
we will check the status of the file in POSIX it self, before we
resume the fop. This helps us avoiding any races mentioned above.
Now e.g. if a write reached POSIX for a file which was actually remote,
it can check the status of the file and will get to know that the file
is remote.  It can error out with this status “remote” and cloudsync
xlator will retry the same operation, once it finished downloading the
file.

This patch includes the setxattr changes to do the post processing of
upload i.e. truncate and setting the remote xattr
"trusted.glusterfs.cs.remote" to indicate the file is REMOTE

Each file will have no xattr if the file is LOCAL, one remote xattr if
the file is REMOTE and a combination of REMOTE and DOWNLOADING xattr if
the file is getting downloaded. There is healing logic of these xattrs
to recover from crash inconsitencies.

Fixes: #387
Change-Id: Ie93c2d41aa8d6a798a39bdbef9d1669f057e5fdb
Signed-off-by: Susant Palai <spalai@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/xlators/storage/posix/src/posix-entry-ops.c b/xlators/storage/posix/src/posix-entry-ops.c
index 69e125a45ab..0abe380ee43 100644
--- a/xlators/storage/posix/src/posix-entry-ops.c
+++ b/xlators/storage/posix/src/posix-entry-ops.c
@@ -252,6 +252,9 @@ posix_lookup (call_frame_t *frame, xlator_t *this,
                 xattr = posix_xattr_fill (this, real_path, loc, NULL, -1, xdata,
                                           &buf);
 
+                posix_cs_maintenance (this, NULL, loc, NULL, &buf, real_path,
+                                   xdata, &xattr, _gf_true);
+
                 if (dict_get (xdata, GF_CLEAN_WRITE_PROTECTION)) {
                         ret = sys_lremovexattr (real_path,
                                                 GF_PROTECT_FROM_EXTERNAL_WRITES);