cifs: don't use vfsmount to pin superblock for oplock breaks
Filesystems aren't really supposed to do anything with a vfsmount. It's
considered a layering violation since vfsmounts are entirely managed at
the VFS layer.
CIFS currently keeps an active reference to a vfsmount in order to
prevent the superblock vanishing before an oplock break has completed.
What we really want to do instead is to keep sb->s_active high until the
oplock break has completed. This patch borrows the scheme that NFS uses
for handling sillyrenames.
An atomic_t is added to the cifs_sb_info. When it transitions from 0 to
1, an extra reference to the superblock is taken (by bumping the
s_active value). When it transitions from 1 to 0, that reference is
dropped and a the superblock teardown may proceed if there are no more
references to it.
Also, the vfsmount pointer is removed from cifsFileInfo and from
cifs_new_fileinfo, and some bogus forward declarations are removed from
cifsfs.h.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 3258c82..cbd468c 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -83,6 +83,24 @@
extern mempool_t *cifs_req_poolp;
extern mempool_t *cifs_mid_poolp;
+void
+cifs_sb_active(struct super_block *sb)
+{
+ struct cifs_sb_info *server = CIFS_SB(sb);
+
+ if (atomic_inc_return(&server->active) == 1)
+ atomic_inc(&sb->s_active);
+}
+
+void
+cifs_sb_deactive(struct super_block *sb)
+{
+ struct cifs_sb_info *server = CIFS_SB(sb);
+
+ if (atomic_dec_and_test(&server->active))
+ deactivate_super(sb);
+}
+
static int
cifs_read_super(struct super_block *sb, void *data,
const char *devname, int silent)