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List: linux-nfs
Subject: [PATCH] mount.nfs: fix ignore EBUSY problem in special scenario
From: "Jianhong.Yin" <yin-jianhong () 163 ! com>
Date: 2019-02-28 5:08:42
Message-ID: 20190228050842.15827-1-yin-jianhong () 163 ! com
[Download RAW message or body]
now mount.nfs ignore EBUSY when the $dir is a mountpoint,
it's not correct in specail scenario for example:
$dir is a mountpoint of other filesystem(let's say tmpfs)
so we must be sure: current nfs mounting has mounted on $dir, then
ignore the EBUSY for user.
- if (errno == EBUSY && is_mountpoint(mi->node))
+ if (errno == EBUSY && is_mountpoint(mi->node) && has_mounted_on(mi->spec, mi->node))
reproducer:
'''
mkdir -p /expdir /mnt/nfsmp /mnt/tmpfs
echo "/expdir *(rw,no_root_squash)" >/etc/exports
service nfs restart
mount -t tmpfs tmpfs /mnt/tmpfs
mount -osharecache localhost:/expdir /mnt/nfsmp #success
mount -osharecache localhost:/expdir /mnt/nfsmp #mounted already, return 0(pass)
mount -osharecache localhost:/expdir /mnt/tmpfs #success
mount -osharecache localhost:/expdir /mnt/tmpfs #mounted already, return 0(pass)
umount /mnt/nfsmp
umount /mnt/tmpfs
mount -ocontext=system_u:object_r:xferlog_t:s0,sharecache localhost:/expdir /mnt/nfsmp
mount -ocontext=system_u:object_r:user_home_dir_t:s0,sharecache localhost:/expdir /mnt/tmpfs
[[ $? = 0 ]] && echo "***test fail: hasn't mounted, should return fail ***"
umount /mnt/nfsmp
'''
Signed-off-by: Jianhong Yin <yin-jianhong@163.com>
---
support/include/misc.h | 1 +
support/misc/mountpoint.c | 26 +++++++++++++++++++++++++-
utils/mount/stropts.c | 2 +-
3 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/support/include/misc.h b/support/include/misc.h
index 06e2a0c..bd02bfc 100644
--- a/support/include/misc.h
+++ b/support/include/misc.h
@@ -19,6 +19,7 @@ char *generic_make_pathname(const char *, const char *);
_Bool generic_setup_basedir(const char *, const char *, char *, const size_t);
extern int is_mountpoint(char *path);
+extern int has_mounted_on(const char *fsname, const char *dir);
/* size of the file pointer buffers for rpc procfs files */
#define RPC_CHAN_BUF_SIZE 32768
diff --git a/support/misc/mountpoint.c b/support/misc/mountpoint.c
index 9f9ce44..7f8a89f 100644
--- a/support/misc/mountpoint.c
+++ b/support/misc/mountpoint.c
@@ -3,9 +3,11 @@
* check if a given path is a mountpoint
*/
+#include <stdio.h>
#include <string.h>
-#include "xcommon.h"
+#include <mntent.h>
#include <sys/stat.h>
+#include "xcommon.h"
#include "misc.h"
int
@@ -38,3 +40,25 @@ is_mountpoint(char *path)
free(dotdot);
return rv;
}
+
+int
+has_mounted_on(const char *fsname, const char *dir)
+{
+ struct mntent *ent;
+ FILE *fp;
+ int ret = 0;
+
+ fp = setmntent("/proc/mounts", "r");
+ if (fp == NULL) {
+ perror("[unlikely] setmntent(3) fail");
+ exit(1);
+ }
+ while (NULL != (ent = getmntent(fp))) {
+ if (!strcmp(ent->mnt_fsname, fsname) && !strcmp(ent->mnt_dir, dir)) {
+ ret = 1;
+ break;
+ }
+ }
+ endmntent(fp);
+ return ret;
+}
diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
index a093926..bffb74a 100644
--- a/utils/mount/stropts.c
+++ b/utils/mount/stropts.c
@@ -1081,7 +1081,7 @@ static int nfsmount_fg(struct nfsmount_info *mi)
return EX_SUCCESS;
#pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
- if (errno == EBUSY && is_mountpoint(mi->node)) {
+ if (errno == EBUSY && is_mountpoint(mi->node) && has_mounted_on(mi->spec, mi->node)) {
#pragma GCC diagnostic warning "-Wdiscarded-qualifiers"
/*
* EBUSY can happen when mounting a filesystem that
--
2.17.2
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