cifs: convert cifsFileInfo->count to non-atomic counter

The count for cifsFileInfo is currently an atomic, but that just adds
complexity for little value. We generally need to hold cifs_file_list_lock
to traverse the lists anyway so we might as well make this counter
non-atomic and simply use the cifs_file_list_lock to protect it.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>

2 files changed, 11 insertions, 6 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 3365e77f6f24..6319db025e7b 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -395,16 +395,19 @@ struct cifsFileInfo {
         struct list_head llist; /* list of byte range locks we have. */
         bool invalidHandle:1;   /* file closed via session abend */
         bool oplock_break_cancelled:1;
-        atomic_t count;         /* reference count */
+        int count;              /* refcount -- protected by cifs_file_list_lock */
         struct mutex fh_mutex; /* prevents reopen race after dead ses*/
         struct cifs_search_info srch_inf;
         struct work_struct oplock_break; /* work for oplock breaks */
 };
 
-/* Take a reference on the file private data */
+/*
+ * Take a reference on the file private data. Must be called with
+ * cifs_file_list_lock held.
+ */
 static inline void cifsFileInfo_get(struct cifsFileInfo *cifs_file)
 {
-        atomic_inc(&cifs_file->count);
+        ++cifs_file->count;
 }
 
 void cifsFileInfo_put(struct cifsFileInfo *cifs_file);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 8c81e7b14d53..baf4b5067ff9 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -232,6 +232,7 @@ cifs_new_fileinfo(__u16 fileHandle, struct file *file,
         if (pCifsFile == NULL)
                 return pCifsFile;
 
+        pCifsFile->count = 1;
         pCifsFile->netfid = fileHandle;
         pCifsFile->pid = current->tgid;
         pCifsFile->uid = current_fsuid();
@@ -242,7 +243,6 @@ cifs_new_fileinfo(__u16 fileHandle, struct file *file,
         mutex_init(&pCifsFile->fh_mutex);
         mutex_init(&pCifsFile->lock_mutex);
         INIT_LIST_HEAD(&pCifsFile->llist);
-        atomic_set(&pCifsFile->count, 1);
         INIT_WORK(&pCifsFile->oplock_break, cifs_oplock_break);
 
         spin_lock(&cifs_file_list_lock);
@@ -267,7 +267,8 @@ cifs_new_fileinfo(__u16 fileHandle, struct file *file,
 
 /*
  * Release a reference on the file private data. This may involve closing
- * the filehandle out on the server.
+ * the filehandle out on the server. Must be called without holding
+ * cifs_file_list_lock.
  */
 void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
 {
@@ -276,7 +277,7 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
         struct cifsLockInfo *li, *tmp;
 
         spin_lock(&cifs_file_list_lock);
-        if (!atomic_dec_and_test(&cifs_file->count)) {
+        if (--cifs_file->count > 0) {
                 spin_unlock(&cifs_file_list_lock);
                 return;
         }
@@ -2322,6 +2323,7 @@ void cifs_oplock_break(struct work_struct *work)
         cifs_oplock_break_put(cfile);
 }
 
+/* must be called while holding cifs_file_list_lock */
 void cifs_oplock_break_get(struct cifsFileInfo *cfile)
 {
         cifs_sb_active(cfile->dentry->d_sb);