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| author | Jeff Layton <jlayton@kernel.org> | 2026-05-22 12:44:19 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-07-04 13:43:35 +0200 |
| commit | 1dd664b39774a9c89b72de8e59bf9ef4b3aaff2e (patch) | |
| tree | adfa7229b222d534c8977bd97f037412ad357739 | |
| parent | c9aefb2b5f11337c9202c5bd0c45d71198449718 (diff) | |
| download | linux-1dd664b39774a9c89b72de8e59bf9ef4b3aaff2e.tar.gz linux-1dd664b39774a9c89b72de8e59bf9ef4b3aaff2e.zip | |
nfsd: reset write verifier on deferred writeback errors
commit 2090b05803faab8a9fa62fbff871007862cac1b7 upstream.
nfsd_vfs_write() and nfsd_commit() both call filemap_check_wb_err() to
detect deferred writeback errors, but neither rotates the server's write
verifier (nn->writeverf) when this check fails. Every other
durable-storage-failure path in these functions calls
commit_reset_write_verifier() before returning an error.
The missing rotation means clients holding UNSTABLE write data under the
current verifier will COMMIT, receive the unchanged verifier back, and
conclude their data is durable — silently dropping data that failed
writeback. This violates the UNSTABLE+COMMIT durability contract
(RFC 1813 §3.3.7, RFC 8881 §18.32).
Add commit_reset_write_verifier() calls at both filemap_check_wb_err()
error sites, matching the pattern used by adjacent error paths in the
same functions. The helper already filters -EAGAIN and -ESTALE
internally, so the calls are unconditionally safe.
Reported-by: Chris Mason <clm@meta.com>
Fixes: 555dbf1a9aac ("nfsd: Replace use of rwsem with errseq_t")
Cc: stable@vger.kernel.org
Assisted-by: kres:claude-opus-4-6
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/nfsd/vfs.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 08c8babfdd75..67d09fcee669 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1203,8 +1203,10 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf, nfsd_stats_io_write_add(nn, exp, *cnt); fsnotify_modify(file); host_err = filemap_check_wb_err(file->f_mapping, since); - if (host_err < 0) + if (host_err < 0) { + commit_reset_write_verifier(nn, rqstp, host_err); goto out_nfserr; + } if (stable && fhp->fh_use_wgather) { host_err = wait_for_concurrent_writes(file); @@ -1370,6 +1372,8 @@ nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf, nfsd_copy_write_verifier(verf, nn); err2 = filemap_check_wb_err(nf->nf_file->f_mapping, since); + if (err2 < 0) + commit_reset_write_verifier(nn, rqstp, err2); err = nfserrno(err2); break; case -EINVAL: |