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[GFS2] flocks from same process trip kernel BUG at fs/gfs2/glock.c:1118!

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This patch adds a new flag to the gfs2_holder structure GL_FLOCK.
It is set on holders of glocks representing flocks. This flag is
checked in add_to_queue() and a process is permitted to queue more
than one holder onto a glock if it is set. This solves the issue
of a process not being able to do multiple flocks on the same file.
Through a single descriptor, a process can now promote and demote
flocks. Through multiple descriptors a process can now queue
multiple flocks on the same file. There's still the problem of
a process deadlocking itself (because gfs2 blocking locks are not
interruptible) by queueing incompatible deadlock.

Signed-off-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Abhijith Das
2007-09-13 23:35:27 -05:00
committed by Steven Whitehouse
parent 1ad38c437f
commit b4c20166dc
3 changed files with 32 additions and 25 deletions
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43
fs/gfs2/glock.c
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@ -1106,24 +1106,31 @@ static void add_to_queue(struct gfs2_holder *gh)
if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
BUG();
existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner_pid);
if (existing) {
print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
printk(KERN_INFO "pid : %d\n", existing->gh_owner_pid);
printk(KERN_INFO "lock type : %d lock state : %d\n",
existing->gh_gl->gl_name.ln_type, existing->gh_gl->gl_state);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
printk(KERN_INFO "pid : %d\n", gh->gh_owner_pid);
printk(KERN_INFO "lock type : %d lock state : %d\n",
gl->gl_name.ln_type, gl->gl_state);
BUG();
}
existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner_pid);
if (existing) {
print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
BUG();
if (!(gh->gh_flags & GL_FLOCK)) {
existing = find_holder_by_owner(&gl->gl_holders,
gh->gh_owner_pid);
if (existing) {
print_symbol(KERN_WARNING "original: %s\n",
existing->gh_ip);
printk(KERN_INFO "pid : %d\n", existing->gh_owner_pid);
printk(KERN_INFO "lock type : %d lock state : %d\n",
existing->gh_gl->gl_name.ln_type,
existing->gh_gl->gl_state);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
printk(KERN_INFO "pid : %d\n", gh->gh_owner_pid);
printk(KERN_INFO "lock type : %d lock state : %d\n",
gl->gl_name.ln_type, gl->gl_state);
BUG();
}
existing = find_holder_by_owner(&gl->gl_waiters3,
gh->gh_owner_pid);
if (existing) {
print_symbol(KERN_WARNING "original: %s\n",
existing->gh_ip);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
BUG();
}
}
if (gh->gh_flags & LM_FLAG_PRIORITY)