From 3e7dfb1659c2888fc0152ec2b02a5e932397bb0a Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 14 Nov 2016 11:19:55 -0500 Subject: 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 Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker --- fs/nfs/nfs4proc.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'fs/nfs/nfs4proc.c') diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 8e25327077e2..0b3cdf856333 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -1451,7 +1451,6 @@ static void nfs_resync_open_stateid_locked(struct nfs4_state *state) } 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 @@ static void nfs_clear_open_stateid_locked(struct nfs4_state *state, } 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 @@ static void nfs_clear_open_stateid(struct nfs4_state *state, 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); -- cgit