Description of problem: When add-brick is done when the the I/O is going on, the I/O operation on the mount point returns ENOENT. The behaviour was seen even with stat-prefetch off

Steps to Reproduce:
1. mkdir /mnt/gluster/files; 
2. for i in `seq 1 20000`; do touch /mnt/gluster/files/$i; done
3. gluster volume add-brick test 192.168.1.34:/brick2


Additional info:
Client log-
[2012-02-08 18:14:13.912635] E [fuse-bridge.c:330:fuse_lookup_resume] 0-fuse: failed to resolve path (null)
[2012-02-08 18:14:13.913085] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.913106] W [fuse-bridge.c:1702:fuse_create_resume] 0-glusterfs-fuse: 13605 CREATE 00000000-0000-0000-0000-000000000000/2602 resolution failed
[2012-02-08 18:14:13.913540] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.913561] E [fuse-bridge.c:330:fuse_lookup_resume] 0-fuse: failed to resolve path (null)
[2012-02-08 18:14:13.917151] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.917194] E [fuse-bridge.c:330:fuse_lookup_resume] 0-fuse: failed to resolve path (null)
[2012-02-08 18:14:13.917637] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.917658] W [fuse-bridge.c:1702:fuse_create_resume] 0-glusterfs-fuse: 13608 CREATE 00000000-0000-0000-0000-000000000000/2603 resolution failed
[2012-02-08 18:14:13.918073] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.918096] E [fuse-bridge.c:330:fuse_lookup_resume] 0-fuse: failed to resolve path (null)
[2012-02-08 18:14:13.922064] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.922109] E [fuse-bridge.c:330:fuse_lookup_resume] 0-fuse: failed to resolve path (null)
[2012-02-08 18:14:13.922567] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.922588] W [fuse-bridge.c:1702:fuse_create_resume] 0-glusterfs-fuse: 13611 CREATE 00000000-0000-0000-0000-000000000000/2604 resolution failed
[2012-02-08 18:14:13.923049] W [fuse-resolve.c:148:fuse_resolve_gfid_cbk] 0-fuse: cffd7c81-8cbe-4c7c-80ee-c640758c5d32: failed to resolve (Invalid argument)
[2012-02-08 18:14:13.923071] E [fuse-bridge.c:330:fuse_lookup_resume] 0-fuse: failed to resolve path (null)