fs/locks: rename some lists and pointers.

struct file lock contains an 'fl_next' pointer which
is used to point to the lock that this request is blocked
waiting for.  So rename it to fl_blocker.

The fl_blocked list_head in an active lock is the head of a list of
blocked requests.  In a request it is a node in that list.
These are two distinct uses, so replace with two list_heads
with different names.
fl_blocked_requests is the head of a list of blocked requests
fl_blocked_member is a node in a member of that list.

The two different list_heads are never used at the same time, but that
will change in a future patch.

Note that a tracepoint is changed to report fl_blocker instead
of fl_next.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 74c33d5..d7ed895 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1103,7 +1103,7 @@ try_again:
        rc = posix_lock_file(file, flock, NULL);
        up_write(&cinode->lock_sem);
        if (rc == FILE_LOCK_DEFERRED) {
-               rc = wait_event_interruptible(flock->fl_wait, !flock->fl_next);
+               rc = wait_event_interruptible(flock->fl_wait, !flock->fl_blocker);
                if (!rc)
                        goto try_again;
                posix_unblock_lock(flock);

diff --git a/fs/locks.c b/fs/locks.c
index 2ecb4db..c6df0c8 100644 (file)
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -189,9 +189,9 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
  * This lock protects the blocked_hash. Generally, if you're accessing it, you
  * want to be holding this lock.
  *
- * In addition, it also protects the fl->fl_block list, and the fl->fl_next
- * pointer for file_lock structures that are acting as lock requests (in
- * contrast to those that are acting as records of acquired locks).
+ * In addition, it also protects the fl->fl_blocked_requests list, and the
+ * fl->fl_blocker pointer for file_lock structures that are acting as lock
+ * requests (in contrast to those that are acting as records of acquired locks).
  *
  * Note that when we acquire this lock in order to change the above fields,
  * we often hold the flc_lock as well. In certain cases, when reading the fields
@@ -293,7 +293,8 @@ static void locks_init_lock_heads(struct file_lock *fl)
 {
        INIT_HLIST_NODE(&fl->fl_link);
        INIT_LIST_HEAD(&fl->fl_list);
-       INIT_LIST_HEAD(&fl->fl_block);
+       INIT_LIST_HEAD(&fl->fl_blocked_requests);
+       INIT_LIST_HEAD(&fl->fl_blocked_member);
        init_waitqueue_head(&fl->fl_wait);
 }
 
@@ -332,7 +333,8 @@ void locks_free_lock(struct file_lock *fl)
 {
        BUG_ON(waitqueue_active(&fl->fl_wait));
        BUG_ON(!list_empty(&fl->fl_list));
-       BUG_ON(!list_empty(&fl->fl_block));
+       BUG_ON(!list_empty(&fl->fl_blocked_requests));
+       BUG_ON(!list_empty(&fl->fl_blocked_member));
        BUG_ON(!hlist_unhashed(&fl->fl_link));
 
        locks_release_private(fl);
@@ -666,8 +668,8 @@ static void locks_delete_global_blocked(struct file_lock *waiter)
 static void __locks_delete_block(struct file_lock *waiter)
 {
        locks_delete_global_blocked(waiter);
-       list_del_init(&waiter->fl_block);
-       waiter->fl_next = NULL;
+       list_del_init(&waiter->fl_blocked_member);
+       waiter->fl_blocker = NULL;
 }
 
 static void locks_delete_block(struct file_lock *waiter)
@@ -683,16 +685,17 @@ static void locks_delete_block(struct file_lock *waiter)
  * it seems like the reasonable thing to do.
  *
  * Must be called with both the flc_lock and blocked_lock_lock held. The
- * fl_block list itself is protected by the blocked_lock_lock, but by ensuring
- * that the flc_lock is also held on insertions we can avoid taking the
- * blocked_lock_lock in some cases when we see that the fl_block list is empty.
+ * fl_blocked_requests list itself is protected by the blocked_lock_lock,
+ * but by ensuring that the flc_lock is also held on insertions we can avoid
+ * taking the blocked_lock_lock in some cases when we see that the
+ * fl_blocked_requests list is empty.
  */
 static void __locks_insert_block(struct file_lock *blocker,
                                        struct file_lock *waiter)
 {
-       BUG_ON(!list_empty(&waiter->fl_block));
-       waiter->fl_next = blocker;
-       list_add_tail(&waiter->fl_block, &blocker->fl_block);
+       BUG_ON(!list_empty(&waiter->fl_blocked_member));
+       waiter->fl_blocker = blocker;
+       list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);
        if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
                locks_insert_global_blocked(waiter);
 }
@@ -716,19 +719,19 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
        /*
         * Avoid taking global lock if list is empty. This is safe since new
         * blocked requests are only added to the list under the flc_lock, and
-        * the flc_lock is always held here. Note that removal from the fl_block
-        * list does not require the flc_lock, so we must recheck list_empty()
-        * after acquiring the blocked_lock_lock.
+        * the flc_lock is always held here. Note that removal from the
+        * fl_blocked_requests list does not require the flc_lock, so we must
+        * recheck list_empty() after acquiring the blocked_lock_lock.
         */
-       if (list_empty(&blocker->fl_block))
+       if (list_empty(&blocker->fl_blocked_requests))
                return;
 
        spin_lock(&blocked_lock_lock);
-       while (!list_empty(&blocker->fl_block)) {
+       while (!list_empty(&blocker->fl_blocked_requests)) {
                struct file_lock *waiter;
 
-               waiter = list_first_entry(&blocker->fl_block,
-                               struct file_lock, fl_block);
+               waiter = list_first_entry(&blocker->fl_blocked_requests,
+                               struct file_lock, fl_blocked_member);
                __locks_delete_block(waiter);
                if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
                        waiter->fl_lmops->lm_notify(waiter);
@@ -878,7 +881,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
 
        hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
                if (posix_same_owner(fl, block_fl))
-                       return fl->fl_next;
+                       return fl->fl_blocker;
        }
        return NULL;
 }
@@ -1237,7 +1240,7 @@ static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
                error = posix_lock_inode(inode, fl, NULL);
                if (error != FILE_LOCK_DEFERRED)
                        break;
-               error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
+               error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);
                if (!error)
                        continue;
 
@@ -1324,7 +1327,7 @@ int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start,
                error = posix_lock_inode(inode, &fl, NULL);
                if (error != FILE_LOCK_DEFERRED)
                        break;
-               error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
+               error = wait_event_interruptible(fl.fl_wait, !fl.fl_blocker);
                if (!error) {
                        /*
                         * If we've been sleeping someone might have
@@ -1518,7 +1521,7 @@ restart:
 
        locks_dispose_list(&dispose);
        error = wait_event_interruptible_timeout(new_fl->fl_wait,
-                                               !new_fl->fl_next, break_time);
+                                               !new_fl->fl_blocker, break_time);
 
        percpu_down_read_preempt_disable(&file_rwsem);
        spin_lock(&ctx->flc_lock);
@@ -1931,7 +1934,7 @@ static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
                error = flock_lock_inode(inode, fl);
                if (error != FILE_LOCK_DEFERRED)
                        break;
-               error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
+               error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);
                if (!error)
                        continue;
 
@@ -2210,7 +2213,7 @@ static int do_lock_file_wait(struct file *filp, unsigned int cmd,
                error = vfs_lock_file(filp, cmd, fl, NULL);
                if (error != FILE_LOCK_DEFERRED)
                        break;
-               error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
+               error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker);
                if (!error)
                        continue;
 
@@ -2581,7 +2584,7 @@ posix_unblock_lock(struct file_lock *waiter)
        int status = 0;
 
        spin_lock(&blocked_lock_lock);
-       if (waiter->fl_next)
+       if (waiter->fl_blocker)
                __locks_delete_block(waiter);
        else
                status = -ENOENT;
@@ -2707,7 +2710,7 @@ static int locks_show(struct seq_file *f, void *v)
 
        lock_get_status(f, fl, iter->li_pos, "");
 
-       list_for_each_entry(bfl, &fl->fl_block, fl_block)
+       list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member)
                lock_get_status(f, bfl, iter->li_pos, " ->");
 
        return 0;

diff --git a/include/linux/fs.h b/include/linux/fs.h
index c95c080..16df3a7 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1044,10 +1044,15 @@ bool opens_in_grace(struct net *);
  * Obviously, the last two criteria only matter for POSIX locks.
  */
 struct file_lock {
-       struct file_lock *fl_next;      /* singly linked list for this inode  */
+       struct file_lock *fl_blocker;   /* The lock, that is blocking us */
        struct list_head fl_list;       /* link into file_lock_context */
        struct hlist_node fl_link;      /* node in global lists */
-       struct list_head fl_block;      /* circular list of blocked processes */
+       struct list_head fl_blocked_requests;   /* list of requests with
+                                                * ->fl_blocker pointing here
+                                                */
+       struct list_head fl_blocked_member;     /* node in
+                                                * ->fl_blocker->fl_blocked_requests
+                                                */
        fl_owner_t fl_owner;
        unsigned int fl_flags;
        unsigned char fl_type;

diff --git a/include/trace/events/filelock.h b/include/trace/events/filelock.h
index 68b17c1..fad7bef 100644 (file)
--- a/include/trace/events/filelock.h
+++ b/include/trace/events/filelock.h
@@ -68,7 +68,7 @@ DECLARE_EVENT_CLASS(filelock_lock,
                __field(struct file_lock *, fl)
                __field(unsigned long, i_ino)
                __field(dev_t, s_dev)
-               __field(struct file_lock *, fl_next)
+               __field(struct file_lock *, fl_blocker)
                __field(fl_owner_t, fl_owner)
                __field(unsigned int, fl_pid)
                __field(unsigned int, fl_flags)
@@ -82,7 +82,7 @@ DECLARE_EVENT_CLASS(filelock_lock,
                __entry->fl = fl ? fl : NULL;
                __entry->s_dev = inode->i_sb->s_dev;
                __entry->i_ino = inode->i_ino;
-               __entry->fl_next = fl ? fl->fl_next : NULL;
+               __entry->fl_blocker = fl ? fl->fl_blocker : NULL;
                __entry->fl_owner = fl ? fl->fl_owner : NULL;
                __entry->fl_pid = fl ? fl->fl_pid : 0;
                __entry->fl_flags = fl ? fl->fl_flags : 0;
@@ -92,9 +92,9 @@ DECLARE_EVENT_CLASS(filelock_lock,
                __entry->ret = ret;
        ),
 
-       TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_pid=%u fl_flags=%s fl_type=%s fl_start=%lld fl_end=%lld ret=%d",
+       TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_blocker=0x%p fl_owner=0x%p fl_pid=%u fl_flags=%s fl_type=%s fl_start=%lld fl_end=%lld ret=%d",
                __entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev),
-               __entry->i_ino, __entry->fl_next, __entry->fl_owner,
+               __entry->i_ino, __entry->fl_blocker, __entry->fl_owner,
                __entry->fl_pid, show_fl_flags(__entry->fl_flags),
                show_fl_type(__entry->fl_type),
                __entry->fl_start, __entry->fl_end, __entry->ret)
@@ -125,7 +125,7 @@ DECLARE_EVENT_CLASS(filelock_lease,
                __field(struct file_lock *, fl)
                __field(unsigned long, i_ino)
                __field(dev_t, s_dev)
-               __field(struct file_lock *, fl_next)
+               __field(struct file_lock *, fl_blocker)
                __field(fl_owner_t, fl_owner)
                __field(unsigned int, fl_flags)
                __field(unsigned char, fl_type)
@@ -137,7 +137,7 @@ DECLARE_EVENT_CLASS(filelock_lease,
                __entry->fl = fl ? fl : NULL;
                __entry->s_dev = inode->i_sb->s_dev;
                __entry->i_ino = inode->i_ino;
-               __entry->fl_next = fl ? fl->fl_next : NULL;
+               __entry->fl_blocker = fl ? fl->fl_blocker : NULL;
                __entry->fl_owner = fl ? fl->fl_owner : NULL;
                __entry->fl_flags = fl ? fl->fl_flags : 0;
                __entry->fl_type = fl ? fl->fl_type : 0;
@@ -145,9 +145,9 @@ DECLARE_EVENT_CLASS(filelock_lease,
                __entry->fl_downgrade_time = fl ? fl->fl_downgrade_time : 0;
        ),
 
-       TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu",
+       TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_blocker=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu",
                __entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev),
-               __entry->i_ino, __entry->fl_next, __entry->fl_owner,
+               __entry->i_ino, __entry->fl_blocker, __entry->fl_owner,
                show_fl_flags(__entry->fl_flags),
                show_fl_type(__entry->fl_type),
                __entry->fl_break_time, __entry->fl_downgrade_time)