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| author | Oleg Nesterov <oleg@redhat.com> | 2023-10-26 17:50:18 +0300 |
|---|---|---|
| committer | Chuck Lever <chuck.lever@oracle.com> | 2024-01-08 01:54:24 +0300 |
| commit | f3734cc4073f68ac3566293acc6d62971c47ad5a (patch) | |
| tree | 8aaf609d1b7373badab1d8748297bda709cf18c2 /fs/nfsd | |
| parent | 74fd48739d0488e39ae18b0168720f449a06690c (diff) | |
| download | linux-f3734cc4073f68ac3566293acc6d62971c47ad5a.tar.xz | |
NFSD: use read_seqbegin() rather than read_seqbegin_or_lock()
The usage of read_seqbegin_or_lock() in nfsd_copy_write_verifier()
is wrong. "seq" is always even and thus "or_lock" has no effect,
this code can never take ->writeverf_lock for writing.
I guess this is fine, nfsd_copy_write_verifier() just copies 8 bytes
and nfsd_reset_write_verifier() is supposed to be very rare operation
so we do not need the adaptive locking in this case.
Yet the code looks wrong and sub-optimal, it can use read_seqbegin()
without changing the behaviour.
[ cel: Note also that it eliminates this Sparse warning:
fs/nfsd/nfssvc.c:360:6: warning: context imbalance in 'nfsd_copy_write_verifier' -
different lock contexts for basic block
]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'fs/nfsd')
| -rw-r--r-- | fs/nfsd/nfssvc.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 7a2bc8e82a63..ee835bf9ee42 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -359,13 +359,12 @@ static bool nfsd_needs_lockd(struct nfsd_net *nn) */ void nfsd_copy_write_verifier(__be32 verf[2], struct nfsd_net *nn) { - int seq = 0; + unsigned int seq; do { - read_seqbegin_or_lock(&nn->writeverf_lock, &seq); + seq = read_seqbegin(&nn->writeverf_lock); memcpy(verf, nn->writeverf, sizeof(nn->writeverf)); - } while (need_seqretry(&nn->writeverf_lock, seq)); - done_seqretry(&nn->writeverf_lock, seq); + } while (read_seqretry(&nn->writeverf_lock, seq)); } static void nfsd_reset_write_verifier_locked(struct nfsd_net *nn) |