After nfsd get exports cache, user cannot umounts the filesystem
which base on for a reference of the vfsmnt.
This patch introduces a new option "allow_umount" for nfsd pining to
the vfsmnt, not get a refernce. At all, user can umount now.
Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
---
support/include/nfs/export.h | 3 ++-
support/nfs/exports.c | 6 ++++++
utils/exportfs/exports.man | 8 ++++++++
3 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/support/include/nfs/export.h b/support/include/nfs/export.h
index 1194255..ca4e0c1 100644
--- a/support/include/nfs/export.h
+++ b/support/include/nfs/export.h
@@ -26,7 +26,8 @@
#define NFSEXP_CROSSMOUNT 0x4000
#define NFSEXP_NOACL 0x8000 /* reserved for possible ACL related use */
#define NFSEXP_V4ROOT 0x10000
-#define NFSEXP_PNFS 0x20000
+#define NFSEXP_PNFS 0x20000
+#define NFSEXP_ALLOW_UMOUNT 0x40000
/*
* All flags supported by the kernel before addition of the
* export_features interface:
diff --git a/support/nfs/exports.c b/support/nfs/exports.c
index 0aea6f1..ed5b984 100644
--- a/support/nfs/exports.c
+++ b/support/nfs/exports.c
@@ -276,6 +276,8 @@ putexportent(struct exportent *ep)
if (ep->e_flags & NFSEXP_NOREADDIRPLUS)
fprintf(fp, "nordirplus,");
fprintf(fp, "%spnfs,", (ep->e_flags & NFSEXP_PNFS)? "" : "no_");
+ if (ep->e_flags & NFSEXP_ALLOW_UMOUNT)
+ fprintf(fp, "allow_umount,");
if (ep->e_flags & NFSEXP_FSID) {
fprintf(fp, "fsid=%d,", ep->e_fsid);
}
@@ -586,6 +588,10 @@ parseopts(char *cp, struct exportent *ep, int warn, int *had_subtree_opt_ptr)
setflags(NFSEXP_PNFS, active, ep);
else if (!strcmp(opt, "no_pnfs"))
clearflags(NFSEXP_PNFS, active, ep);
+ else if (!strcmp(opt, "allow_umount"))
+ setflags(NFSEXP_ALLOW_UMOUNT, active, ep);
+ else if (!strcmp(opt, "no_allow_umount"))
+ clearflags(NFSEXP_ALLOW_UMOUNT, active, ep);
else if (strncmp(opt, "anonuid=", 8) == 0) {
char *oe;
ep->e_anonuid = strtol(opt+8, &oe, 10);
diff --git a/utils/exportfs/exports.man b/utils/exportfs/exports.man
index 9309246..d3947a4 100644
--- a/utils/exportfs/exports.man
+++ b/utils/exportfs/exports.man
@@ -417,6 +417,14 @@ devices. The default can be explicitly requested with the
.I no_pnfs
option.
+.TP
+.IR allow_umount
+This option allows user un-mounting the filesystem where cached nfsd exports
+is based on. Otherwise, the kernel may returns -EBUSY and un-mounting fail.
+The default is without the
+.I allow_umount
+option.
+
.SS User ID Mapping
.PP
.B nfsd
--
2.4.1
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
