readdir is supposed to be non-re-entrant only with respect to the
given dir stream, not the whole process.

What that means is the static struct dirent that we maintain in
libglusterfsclient should be per-directory handle and not
process-wide.

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

As of now, we use 1024 bytes as the buffer for reading directory
entries. If a directory as many files, then its possible that it does
not fit into this buffer, thereby requiring more than one call to
readdir. Now suppose the last bunch of directories fit more or less
exactly int the 1024 byte buffer. If this happens, the offset
extracted by the current logic(in libgf_client_readdir) never gets
updated beyond the first entry in this last block, because the last
block's first entry always remains same. This explanation is
convoluted, I know, but I too found out the hard way.

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

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

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

This commit does two things:
1. Changes glusterfs_readdir prototype to conform to the POSIX
readdir().
2. Uses a 1024-byte value instead of sizeof(struct dirent) for the
@size for libgf_client_readdir. This allows even larger names to fit
into a single readdir request to the server.

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

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

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

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

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

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