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/file.c b/fs/cifs/file.c
index c302b9c..fd78a35 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -282,7 +282,6 @@
}
pCifsFile = cifs_new_fileinfo(inode, netfid, file,
- file->f_path.mnt,
tlink, oflags, oplock);
if (pCifsFile == NULL) {
CIFSSMBClose(xid, tcon, netfid);
@@ -375,8 +374,8 @@
if (rc != 0)
goto out;
- pCifsFile = cifs_new_fileinfo(inode, netfid, file, file->f_path.mnt,
- tlink, file->f_flags, oplock);
+ pCifsFile = cifs_new_fileinfo(inode, netfid, file, tlink,
+ file->f_flags, oplock);
if (pCifsFile == NULL) {
rc = -ENOMEM;
goto out;
@@ -2381,14 +2380,14 @@
void cifs_oplock_break_get(struct cifsFileInfo *cfile)
{
- mntget(cfile->mnt);
+ cifs_sb_active(cfile->dentry->d_sb);
cifsFileInfo_get(cfile);
}
void cifs_oplock_break_put(struct cifsFileInfo *cfile)
{
- mntput(cfile->mnt);
cifsFileInfo_put(cfile);
+ cifs_sb_deactive(cfile->dentry->d_sb);
}
const struct address_space_operations cifs_addr_ops = {