From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suresh Jayaraman Subject: Re: [PATCH 13/15] cifs: convert cifsFileInfo->count to non-atomic counter Date: Mon, 11 Oct 2010 11:16:19 +0530 Message-ID: <4CB2A4AB.2000503@suse.de> References: <1286559072-29032-1-git-send-email-jlayton@redhat.com> <1286559072-29032-14-git-send-email-jlayton@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jeff Layton Return-path: In-Reply-To: <1286559072-29032-14-git-send-email-jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-cifs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 > --- > 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