NFSv4: Fix CLOSE races with OPEN
If the reply to a successful CLOSE call races with an OPEN to the same
file, we can end up scribbling over the stateid that represents the
new open state.
The race looks like:
Client Server
====== ======
CLOSE stateid A on file "foo"
CLOSE stateid A, return stateid C
OPEN file "foo"
OPEN "foo", return stateid B
Receive reply to OPEN
Reset open state for "foo"
Associate stateid B to "foo"
Receive CLOSE for A
Reset open state for "foo"
Replace stateid B with C
The fix is to examine the argument of the CLOSE, and check for a match
with the current stateid "other" field. If the two do not match, then
the above race occurred, and we should just ignore the CLOSE.
Reported-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 9b3a82a..1452177 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -542,6 +542,13 @@
return test_bit(NFS_STATE_RECOVERY_FAILED, &state->flags) == 0;
}
+static inline bool nfs4_state_match_open_stateid_other(const struct nfs4_state *state,
+ const nfs4_stateid *stateid)
+{
+ return test_bit(NFS_OPEN_STATE, &state->flags) &&
+ nfs4_stateid_match_other(&state->open_stateid, stateid);
+}
+
#else
#define nfs4_close_state(a, b) do { } while (0)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8e25327..0b3cdf8 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1451,7 +1451,6 @@
}
static void nfs_clear_open_stateid_locked(struct nfs4_state *state,
- nfs4_stateid *arg_stateid,
nfs4_stateid *stateid, fmode_t fmode)
{
clear_bit(NFS_O_RDWR_STATE, &state->flags);
@@ -1469,10 +1468,9 @@
}
if (stateid == NULL)
return;
- /* Handle races with OPEN */
- if (!nfs4_stateid_match_other(arg_stateid, &state->open_stateid) ||
- (nfs4_stateid_match_other(stateid, &state->open_stateid) &&
- !nfs4_stateid_is_newer(stateid, &state->open_stateid))) {
+ /* Handle OPEN+OPEN_DOWNGRADE races */
+ if (nfs4_stateid_match_other(stateid, &state->open_stateid) &&
+ !nfs4_stateid_is_newer(stateid, &state->open_stateid)) {
nfs_resync_open_stateid_locked(state);
return;
}
@@ -1486,7 +1484,9 @@
nfs4_stateid *stateid, fmode_t fmode)
{
write_seqlock(&state->seqlock);
- nfs_clear_open_stateid_locked(state, arg_stateid, stateid, fmode);
+ /* Ignore, if the CLOSE argment doesn't match the current stateid */
+ if (nfs4_state_match_open_stateid_other(state, arg_stateid))
+ nfs_clear_open_stateid_locked(state, stateid, fmode);
write_sequnlock(&state->seqlock);
if (test_bit(NFS_STATE_RECLAIM_NOGRACE, &state->flags))
nfs4_schedule_state_manager(state->owner->so_server->nfs_client);