nfsd4: acquire only one lease per file

Instead of acquiring one lease each time another client opens a file,
nfsd can acquire just one lease to represent all of them, and reference
count it to determine when to release it.

This fixes a regression introduced by
c45821d263a8a5109d69a9e8942b8d65bcd5f31a "locks: eliminate fl_mylease
callback": after that patch, only the struct file * is used to determine
who owns a given lease.  But since we recently converted the server to
share a single struct file per open, if we acquire multiple leases on
the same file from nfsd, it then becomes impossible on unlocking a lease
to determine which of those leases (all of whom share the same struct
file *) we meant to remove.

Thanks to Takashi Iwai <tiwai@suse.de> for catching a bug in a previous
version of this patch.

Tested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 3074656..2d31224 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -83,8 +83,6 @@ struct nfs4_delegation {
 	atomic_t		dl_count;       /* ref count */
 	struct nfs4_client	*dl_client;
 	struct nfs4_file	*dl_file;
-	struct file		*dl_vfs_file;
-	struct file_lock	*dl_flock;
 	u32			dl_type;
 	time_t			dl_time;
 /* For recall: */
@@ -379,6 +377,9 @@ struct nfs4_file {
 	 */
 	atomic_t		fi_readers;
 	atomic_t		fi_writers;
+	struct file		*fi_deleg_file;
+	struct file_lock	*fi_lease;
+	atomic_t		fi_delegees;
 	struct inode		*fi_inode;
 	u32                     fi_id;      /* used with stateowner->so_id 
 					     * for stateid_hashtbl hash */