Messages in this thread Patch in this message | | | From | NeilBrown <> | Date | Mon, 23 Oct 2017 11:53:49 +1100 | Subject | [PATCH 7/9] staging: lustre: ldlm: tidy list walking in ldlm_flock() |
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Use list_for_each_entry variants to avoid the explicit list_entry() calls. This allows us to use list_for_each_entry_safe_from() instread of adding a local list-walking macro.
Also improve some comments so that it is more obvious that the locks are sorted per-owner and that we need to find the insertion point.
Signed-off-by: NeilBrown <neilb@suse.com> --- drivers/staging/lustre/lustre/ldlm/ldlm_flock.c | 45 ++++++++++------------- 1 file changed, 19 insertions(+), 26 deletions(-)
diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c index 1bf56892fcf5..0bf6dce1c5b1 100644 --- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c @@ -59,17 +59,6 @@ #include <linux/list.h> #include "ldlm_internal.h" -/** - * list_for_remaining_safe - iterate over the remaining entries in a list - * and safeguard against removal of a list entry. - * \param pos the &struct list_head to use as a loop counter. pos MUST - * have been initialized prior to using it in this macro. - * \param n another &struct list_head to use as temporary storage - * \param head the head for your list. - */ -#define list_for_remaining_safe(pos, n, head) \ - for (n = pos->next; pos != (head); pos = n, n = pos->next) - static inline int ldlm_same_flock_owner(struct ldlm_lock *lock, struct ldlm_lock *new) { @@ -125,8 +114,8 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) { struct ldlm_resource *res = req->l_resource; struct ldlm_namespace *ns = ldlm_res_to_ns(res); - struct list_head *tmp; - struct list_head *ownlocks = NULL; + struct ldlm_lock *tmp; + struct ldlm_lock *ownlocks = NULL; struct ldlm_lock *lock = NULL; struct ldlm_lock *new = req; struct ldlm_lock *new2 = NULL; @@ -151,23 +140,23 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) /* This loop determines where this processes locks start * in the resource lr_granted list. */ - list_for_each(tmp, &res->lr_granted) { - lock = list_entry(tmp, struct ldlm_lock, - l_res_link); + list_for_each_entry(lock, &res->lr_granted, l_res_link) { if (ldlm_same_flock_owner(lock, req)) { - ownlocks = tmp; + ownlocks = lock; break; } } - /* Scan the locks owned by this process that overlap this request. + /* Scan the locks owned by this process to find the insertion point + * (as locks are ordered), and to handle overlaps. * We may have to merge or split existing locks. */ - if (!ownlocks) - ownlocks = &res->lr_granted; - - list_for_remaining_safe(ownlocks, tmp, &res->lr_granted) { - lock = list_entry(ownlocks, struct ldlm_lock, l_res_link); + if (ownlocks) + lock = ownlocks; + else + lock = list_entry(&res->lr_granted, + struct ldlm_lock, l_res_link); + list_for_each_entry_safe_from(lock, tmp, &res->lr_granted, l_res_link) { if (!ldlm_same_flock_owner(lock, new)) break; @@ -295,7 +284,7 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) lock->l_granted_mode); /* insert new2 at lock */ - ldlm_resource_add_lock(res, ownlocks, new2); + ldlm_resource_add_lock(res, &lock->l_res_link, new2); LDLM_LOCK_RELEASE(new2); break; } @@ -309,8 +298,12 @@ static int ldlm_process_flock_lock(struct ldlm_lock *req) if (!added) { list_del_init(&req->l_res_link); - /* insert new lock before ownlocks in list. */ - ldlm_resource_add_lock(res, ownlocks, req); + /* insert new lock before "lock", which might be the + * next lock for this owner, or might be the first + * lock for the next owner, or might not be a lock at + * all, but instead points at the head of the list + */ + ldlm_resource_add_lock(res, &lock->l_res_link, req); } /* In case we're reprocessing the requested lock we can't destroy
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