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>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 4dd9283885e745bafdd7dce81e5456f98c5635c9..5e64748a29173d75ad976c0375f7152d5ae0171d 100644 (file)
--- 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