Rename struct file->f_ep_lock

This lock moves out of the CONFIG_EPOLL ifdef and becomes f_lock.  For now,
epoll remains the only user, but a future patch will use it to protect
f_flags as well.

Cc: Davide Libenzi <davidel@xmailserver.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

4 files changed, 9 insertions, 7 deletions

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 011b9b8c90c6..c5c424f23fd5 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -417,10 +417,10 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi)
         ep_unregister_pollwait(ep, epi);
 
         /* Remove the current item from the list of epoll hooks */
-        spin_lock(&file->f_ep_lock);
+        spin_lock(&file->f_lock);
         if (ep_is_linked(&epi->fllink))
                 list_del_init(&epi->fllink);
-        spin_unlock(&file->f_ep_lock);
+        spin_unlock(&file->f_lock);
 
         rb_erase(&epi->rbn, &ep->rbr);
 
@@ -538,7 +538,7 @@ void eventpoll_release_file(struct file *file)
         struct epitem *epi;
 
         /*
-         * We don't want to get "file->f_ep_lock" because it is not
+         * We don't want to get "file->f_lock" because it is not
          * necessary. It is not necessary because we're in the "struct file"
          * cleanup path, and this means that noone is using this file anymore.
          * So, for example, epoll_ctl() cannot hit here sicne if we reach this
@@ -547,6 +547,8 @@ void eventpoll_release_file(struct file *file)
          * will correctly serialize the operation. We do need to acquire
          * "ep->mtx" after "epmutex" because ep_remove() requires it when called
          * from anywhere but ep_free().
+         *
+         * Besides, ep_remove() acquires the lock, so we can't hold it here.
          */
         mutex_lock(&epmutex);
 
@@ -785,9 +787,9 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
                 goto error_unregister;
 
         /* Add the current item to the list of active epoll hook for this file */
-        spin_lock(&tfile->f_ep_lock);
+        spin_lock(&tfile->f_lock);
         list_add_tail(&epi->fllink, &tfile->f_ep_links);
-        spin_unlock(&tfile->f_ep_lock);
+        spin_unlock(&tfile->f_lock);
 
         /*
          * Add the current item to the RB tree. All RB tree operations are
diff --git a/fs/file_table.c b/fs/file_table.c
index bbeeac6efa1a..aa1e18050282 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -127,6 +127,7 @@ struct file *get_empty_filp(void)
         atomic_long_set(&f->f_count, 1);
         rwlock_init(&f->f_owner.lock);
         f->f_cred = get_cred(cred);
+        spin_lock_init(&f->f_lock);
         eventpoll_init_file(f);
         /* f->f_version: 0 */
         return f;
diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index f1e1d3c47125..f6856a5a1d4b 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -61,7 +61,6 @@ struct file;
 static inline void eventpoll_init_file(struct file *file)
 {
         INIT_LIST_HEAD(&file->f_ep_links);
-        spin_lock_init(&file->f_ep_lock);
 }
 
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 92734c0012e6..2011600d12c7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -848,6 +848,7 @@ struct file {
 #define f_dentry        f_path.dentry
 #define f_vfsmnt        f_path.mnt
         const struct file_operations    *f_op;
+        spinlock_t              f_lock;  /* f_ep_links */
         atomic_long_t           f_count;
         unsigned int            f_flags;
         fmode_t                 f_mode;
@@ -866,7 +867,6 @@ struct file {
 #ifdef CONFIG_EPOLL
         /* Used by fs/eventpoll.c to link all the hooks to this file */
         struct list_head        f_ep_links;
-        spinlock_t              f_ep_lock;
 #endif /* #ifdef CONFIG_EPOLL */
         struct address_space    *f_mapping;
 #ifdef CONFIG_DEBUG_WRITECOUNT