diff options
| author | Andrew Elble <aweits@rit.edu> | 2015-12-02 09:20:57 -0500 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2016-02-01 12:39:50 -0500 |
| commit | 40b7566cb9872529f0b95bd913e16022e1107731 (patch) | |
| tree | c830e5bb5ac6aa3efd0d736ebae62fd59fa8f811 /fs/nfs | |
| parent | 33c7c20d62a7916522628fbb45bb65cbc0b9f899 (diff) | |
nfs: Fix race in __update_open_stateid()
[ Upstream commit 361cad3c89070aeb37560860ea8bfc092d545adc ]
We've seen this in a packet capture - I've intermixed what I
think was going on. The fix here is to grab the so_lock sooner.
1964379 -> #1 open (for write) reply seqid=1
1964393 -> #2 open (for read) reply seqid=2
__nfs4_close(), state->n_wronly--
nfs4_state_set_mode_locked(), changes state->state = [R]
state->flags is [RW]
state->state is [R], state->n_wronly == 0, state->n_rdonly == 1
1964398 -> #3 open (for write) call -> because close is already running
1964399 -> downgrade (to read) call seqid=2 (close of #1)
1964402 -> #3 open (for write) reply seqid=3
__update_open_stateid()
nfs_set_open_stateid_locked(), changes state->flags
state->flags is [RW]
state->state is [R], state->n_wronly == 0, state->n_rdonly == 1
new sequence number is exposed now via nfs4_stateid_copy()
next step would be update_open_stateflags(), pending so_lock
1964403 -> downgrade reply seqid=2, fails with OLD_STATEID (close of #1)
nfs4_close_prepare() gets so_lock and recalcs flags -> send close
1964405 -> downgrade (to read) call seqid=3 (close of #1 retry)
__update_open_stateid() gets so_lock
* update_open_stateflags() updates state->n_wronly.
nfs4_state_set_mode_locked() updates state->state
state->flags is [RW]
state->state is [RW], state->n_wronly == 1, state->n_rdonly == 1
* should have suppressed the preceding nfs4_close_prepare() from
sending open_downgrade
1964406 -> write call
1964408 -> downgrade (to read) reply seqid=4 (close of #1 retry)
nfs_clear_open_stateid_locked()
state->flags is [R]
state->state is [RW], state->n_wronly == 1, state->n_rdonly == 1
1964409 -> write reply (fails, openmode)
Signed-off-by: Andrew Elble <aweits@rit.edu>
Cc: stable@vger,kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'fs/nfs')
| -rw-r--r-- | fs/nfs/nfs4proc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 8f393fcc313b..1310a710192b 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -1284,6 +1284,7 @@ static void __update_open_stateid(struct nfs4_state *state, nfs4_stateid *open_s * Protect the call to nfs4_state_set_mode_locked and * serialise the stateid update */ + spin_lock(&state->owner->so_lock); write_seqlock(&state->seqlock); if (deleg_stateid != NULL) { nfs4_stateid_copy(&state->stateid, deleg_stateid); @@ -1292,7 +1293,6 @@ static void __update_open_stateid(struct nfs4_state *state, nfs4_stateid *open_s if (open_stateid != NULL) nfs_set_open_stateid_locked(state, open_stateid, fmode); write_sequnlock(&state->seqlock); - spin_lock(&state->owner->so_lock); update_open_stateflags(state, fmode); spin_unlock(&state->owner->so_lock); } |