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nfsd: reduce want-write range in nfsd4_create_file()

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nfsd4_create_file() needs write access to the mount for two purposes:

1/ to create/open the file.
2/ to set attributes on the newly created (or pre-existing) file.

Currently this is all handled by holding the write access across the
open and the setattr.  A subsequent patch will necessarily change how
write access is gained for the open.  So we reduce the range for the
first want_write, and add another one to cover setattr.  If we failed to
get write access, it is only fatal if there were attrs to set.

We call nfsd_create_setattr() if at all possible, even when no attrs, as
it also calls commit_metadata and we need to be certain that the file
creation has been synced.  If the mount became read-only since the
creation happened, we can safely assume that the sync happened as part
of that.

Signed-off-by: NeilBrown <neil@brown.name>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260717093001.1972119-16-neilb@ownmail.net
Signed-off-by: Chuck Lever <cel@kernel.org>
This commit is contained in:
NeilBrown 2026-07-17 19:28:03 +10:00 committed by Chuck Lever
parent aefe074002
commit 5245bde421
1 changed files with 14 additions and 3 deletions
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17
fs/nfsd/nfs4proc.c
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@ -343,6 +343,8 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
&QSTR_LEN(open->op_fname, open->op_fnamelen));
if (IS_ERR(child)) {
status = nfserrno(PTR_ERR(child));
if (!want_write_err)
fh_drop_write(fhp);
goto out;
}
path.dentry = child;
@ -377,6 +379,8 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
}
}
end_creating(child);
if (!want_write_err)
fh_drop_write(fhp);
if (status != nfs_ok)
goto out;
@ -420,7 +424,16 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
iap->ia_valid &= ~ATTR_SIZE;
status = nfsd_create_setattr(rqstp, fhp, resfhp, &attrs);
/* We will need write access to set the attrs */
want_write_err = fh_want_write(fhp);
if (!want_write_err) {
status = nfsd_create_setattr(rqstp, fhp,
resfhp, &attrs);
fh_drop_write(fhp);
} else if (nfsd_attrs_valid(&attrs)) {
/* Needed write access */
status = nfserrno(want_write_err);
}
if (attrs.na_labelerr)
open->op_bmval[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
@ -431,8 +444,6 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
if (attrs.na_paclerr)
open->op_bmval[2] &= ~FATTR4_WORD2_POSIX_ACCESS_ACL;
out:
if (!want_write_err)
fh_drop_write(fhp);
nfsd_attrs_free(&attrs);
return status;
}