locks: give lm_break a return value
Christoph suggests:
"Add a return value to lm_break so that the lock manager can tell the
core code "you can delete this lease right now". That gets rid of
the games with the timeout which require all kinds of race avoidance
code in the users."
Do that here and have the nfsd lease break routine use it when it detects
that there was a race between setting up the lease and it being broken.
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/locks.c b/fs/locks.c
index 7d627ac..aed4a95 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -427,9 +427,11 @@
}
/* default lease lock manager operations */
-static void lease_break_callback(struct file_lock *fl)
+static bool
+lease_break_callback(struct file_lock *fl)
{
kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
+ return false;
}
static void
@@ -1382,7 +1384,7 @@
{
int error = 0;
struct file_lock *new_fl;
- struct file_lock *fl;
+ struct file_lock *fl, **before;
unsigned long break_time;
int want_write = (mode & O_ACCMODE) != O_RDONLY;
LIST_HEAD(dispose);
@@ -1406,7 +1408,9 @@
break_time++; /* so that 0 means no break time */
}
- for (fl = inode->i_flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
+ for (before = &inode->i_flock;
+ ((fl = *before) != NULL) && IS_LEASE(fl);
+ before = &fl->fl_next) {
if (!leases_conflict(fl, new_fl))
continue;
if (want_write) {
@@ -1420,9 +1424,14 @@
fl->fl_flags |= FL_DOWNGRADE_PENDING;
fl->fl_downgrade_time = break_time;
}
- fl->fl_lmops->lm_break(fl);
+ if (fl->fl_lmops->lm_break(fl))
+ locks_delete_lock(before, &dispose);
}
+ fl = inode->i_flock;
+ if (!fl || !IS_LEASE(fl))
+ goto out;
+
if (mode & O_NONBLOCK) {
trace_break_lease_noblock(inode, new_fl);
error = -EWOULDBLOCK;