CIFS: Do not kmalloc under the flocks spinlock

Reorganize the code to make the memory already allocated before
spinlock'ed loop.

Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 56 insertions, 13 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 4dd9283885e7..5e64748a2917 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -920,16 +920,26 @@ cifs_push_mandatory_locks(struct cifsFileInfo *cfile)
         for (lockp = &inode->i_flock; *lockp != NULL; \
              lockp = &(*lockp)->fl_next)
 
+struct lock_to_push {
+        struct list_head llist;
+        __u64 offset;
+        __u64 length;
+        __u32 pid;
+        __u16 netfid;
+        __u8 type;
+};
+
 static int
 cifs_push_posix_locks(struct cifsFileInfo *cfile)
 {
         struct cifsInodeInfo *cinode = CIFS_I(cfile->dentry->d_inode);
         struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
         struct file_lock *flock, **before;
-        struct cifsLockInfo *lck, *tmp;
+        unsigned int count = 0, i = 0;
         int rc = 0, xid, type;
+        struct list_head locks_to_send, *el;
+        struct lock_to_push *lck, *tmp;
         __u64 length;
-        struct list_head locks_to_send;
 
         xid = GetXid();
 
@@ -940,29 +950,55 @@ cifs_push_posix_locks(struct cifsFileInfo *cfile)
                 return rc;
         }
 
+        lock_flocks();
+        cifs_for_each_lock(cfile->dentry->d_inode, before) {
+                if ((*before)->fl_flags & FL_POSIX)
+                        count++;
+        }
+        unlock_flocks();
+
         INIT_LIST_HEAD(&locks_to_send);
 
+        /*
+         * Allocating count locks is enough because no locks can be added to
+         * the list while we are holding cinode->lock_mutex that protects
+         * locking operations of this inode.
+         */
+        for (; i < count; i++) {
+                lck = kmalloc(sizeof(struct lock_to_push), GFP_KERNEL);
+                if (!lck) {
+                        rc = -ENOMEM;
+                        goto err_out;
+                }
+                list_add_tail(&lck->llist, &locks_to_send);
+        }
+
+        i = 0;
+        el = locks_to_send.next;
         lock_flocks();
         cifs_for_each_lock(cfile->dentry->d_inode, before) {
+                if (el == &locks_to_send) {
+                        /* something is really wrong */
+                        cERROR(1, "Can't push all brlocks!");
+                        break;
+                }
                 flock = *before;
+                if ((flock->fl_flags & FL_POSIX) == 0)
+                        continue;
                 length = 1 + flock->fl_end - flock->fl_start;
                 if (flock->fl_type == F_RDLCK || flock->fl_type == F_SHLCK)
                         type = CIFS_RDLCK;
                 else
                         type = CIFS_WRLCK;
-
-                lck = cifs_lock_init(flock->fl_start, length, type,
-                                     cfile->netfid);
-                if (!lck) {
-                        rc = -ENOMEM;
-                        goto send_locks;
-                }
+                lck = list_entry(el, struct lock_to_push, llist);
                 lck->pid = flock->fl_pid;
-
-                list_add_tail(&lck->llist, &locks_to_send);
+                lck->netfid = cfile->netfid;
+                lck->length = length;
+                lck->type = type;
+                lck->offset = flock->fl_start;
+                i++;
+                el = el->next;
         }
-
-send_locks:
         unlock_flocks();
 
         list_for_each_entry_safe(lck, tmp, &locks_to_send, llist) {
@@ -979,11 +1015,18 @@ send_locks:
                 kfree(lck);
         }
 
+out:
         cinode->can_cache_brlcks = false;
         mutex_unlock(&cinode->lock_mutex);
 
         FreeXid(xid);
         return rc;
+err_out:
+        list_for_each_entry_safe(lck, tmp, &locks_to_send, llist) {
+                list_del(&lck->llist);
+                kfree(lck);
+        }
+        goto out;
 }
 
 static int