On 10/08/2010 11:01 PM, Jeff Layton wrote:
> 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@xxxxxxxxxx>
> ---
> fs/cifs/cifsglob.h | 9 ++++++---
> fs/cifs/file.c | 8 +++++---
> 2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index c928e39..2327dcb 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -393,16 +393,19 @@ 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 8cedcd7..7b8122b 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -172,6 +172,7 @@ 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();
> @@ -182,7 +183,6 @@ 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);
> @@ -203,7 +203,8 @@ 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)
> {
> @@ -212,7 +213,7 @@ 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;
> }
> @@ -2254,6 +2255,7 @@ 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);
Looks correct to me.
Reviewed-by: Suresh Jayaraman <sjayaraman@xxxxxxx>
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