cifs: add refcounting to cifs_readdata structures

This isn't strictly necessary for the async readpages code, but the
uncached version will need to be able to collect the replies after
issuing the calls. Add a kref to cifs_readdata and use change the
code to take and put references appropriately.

Signed-off-by: Jeff Layton <jlayton@redhat.com>

3 files changed, 19 insertions, 7 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index f309b43848f..63e91c79564 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -464,6 +464,7 @@ extern int SMBencrypt(unsigned char *passwd, const unsigned char *c8,
 
 /* asynchronous read support */
 struct cifs_readdata {
+        struct kref                     refcount;
         struct cifsFileInfo             *cfile;
         struct address_space            *mapping;
         __u64                           offset;
@@ -478,6 +479,7 @@ struct cifs_readdata {
         struct kvec                     iov[1];
 };
 
+void cifs_readdata_release(struct kref *refcount);
 int cifs_async_readv(struct cifs_readdata *rdata);
 
 /* asynchronous write support */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 3aa1fcc1515..45633da461a 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1635,12 +1635,15 @@ cifs_async_readv(struct cifs_readdata *rdata)
         rdata->iov[0].iov_base = smb;
         rdata->iov[0].iov_len = be32_to_cpu(smb->hdr.smb_buf_length) + 4;
 
+        kref_get(&rdata->refcount);
         rc = cifs_call_async(tcon->ses->server, rdata->iov, 1,
                              cifs_readv_receive, cifs_readv_callback,
                              rdata, false);
 
         if (rc == 0)
                 cifs_stats_inc(&tcon->num_reads);
+        else
+                kref_put(&rdata->refcount, cifs_readdata_release);
 
         cifs_small_buf_release(smb);
         return rc;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 183381d9c4c..ae285e0cf67 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2347,16 +2347,22 @@ cifs_readdata_alloc(unsigned int nr_vecs, work_func_t complete)
         rdata = kzalloc(sizeof(*rdata) +
                         sizeof(struct kvec) * nr_vecs, GFP_KERNEL);
         if (rdata != NULL) {
+                kref_init(&rdata->refcount);
                 INIT_WORK(&rdata->work, complete);
                 INIT_LIST_HEAD(&rdata->pages);
         }
         return rdata;
 }
 
-static void
-cifs_readdata_free(struct cifs_readdata *rdata)
+void
+cifs_readdata_release(struct kref *refcount)
 {
-        cifsFileInfo_put(rdata->cfile);
+        struct cifs_readdata *rdata = container_of(refcount,
+                                        struct cifs_readdata, refcount);
+
+        if (rdata->cfile)
+                cifsFileInfo_put(rdata->cfile);
+
         kfree(rdata);
 }
 
@@ -2651,7 +2657,7 @@ cifs_readv_complete(struct work_struct *work)
 
                 page_cache_release(page);
         }
-        cifs_readdata_free(rdata);
+        kref_put(&rdata->refcount, cifs_readdata_release);
 }
 
 static int
@@ -2837,9 +2843,8 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                 }
 
                 spin_lock(&cifs_file_list_lock);
-                cifsFileInfo_get(open_file);
                 spin_unlock(&cifs_file_list_lock);
-                rdata->cfile = open_file;
+                rdata->cfile = cifsFileInfo_get(open_file);
                 rdata->mapping = mapping;
                 rdata->offset = offset;
                 rdata->bytes = bytes;
@@ -2864,9 +2869,11 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
                                 unlock_page(page);
                                 page_cache_release(page);
                         }
-                        cifs_readdata_free(rdata);
+                        kref_put(&rdata->refcount, cifs_readdata_release);
                         break;
                 }
+
+                kref_put(&rdata->refcount, cifs_readdata_release);
         }
 
         return rc;