On Tuesday 07 June 2011 10:54 AM, Daniel wrote:
Hello hackers:
I am learning glusterfs and get one question when I reading
contrib/fuse-lib/mount.c fuse_mnt_add_mount(). Why does it fork four
times and the grand-grand-child exec("/bin/mount")? What is the benefit
and the consideration?
As I see it, it forks thrice. Here is what I understand from the code:
+---------------------+
| fuse_mnt_add_mount()|<------------------------------+
| fork and wait for | |
| child to return | |
+-----+---------------+ |
| |
| |
X |
/ \ |
/if \ |
/sync-\ NO +---------------------------+ |
X mtab X-------->| Do async ops by returning | |
\ == 1/ fork() | from here so that parent | |
\ / | does not wait. But before | |
\ / | doing that, create a dummy| |
X | parent to wait for child | |
| YES | that does the /bin/mount | |
| +------------+--------------+ |
| fork() | |
V | |
+-----+----------+ | fork() -> Parent returns here.
| Child: execl | v
| /bin/mount with| +---------------+
| -f option to | |dummy parent: |
| only populate | fork() | fork and wait |
| mtab but don't |<--------+ for /bin/mount|
| actually mount | | to return |
| anything. | +---------------+
+----------------+
HTH,
Pavan
Thank you
Daniel
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