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- fix fix-umount-to-mount-race patch (bug 1399213).

This commit is contained in:
Ian Kent 2016-12-19 11:14:54 +08:00
parent cc01065e15
commit 38fe2a08cf
2 changed files with 87 additions and 16 deletions
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98
am-utils-6.2-fix-umount-to-mount-race.patch
View File

@ -1,6 +1,6 @@
am-utils-6.2 - fix umount to mount race
From: Richard P <richardp345@gmail.com>
From: Ian Kent <raven@themaw.net>
If a mount request arrives while its mount fs is being umounted the
the reference count of the mount fs never reaches 1 so the location
@ -10,18 +10,39 @@ This leads to amd thinking the mount fs is still mounted and the
mount request succeeds without its corresponding target being
mounted.
This patch from Richard P (with an added fix to a log message)
fixes the problem.
Signed-off-by: Richard P <richardp345@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
---
amd/amfs_generic.c | 8 ++++++--
amd/autil.c | 6 ++++++
2 files changed, 12 insertions(+), 2 deletions(-)
amd/amd.h | 1 +
amd/amfs_generic.c | 10 +++++++---
amd/autil.c | 9 +++++++++
amd/map.c | 13 ++++++++++++-
4 files changed, 29 insertions(+), 4 deletions(-)
--- am-utils-6.2.orig/amd/amfs_generic.c
+++ am-utils-6.2/amd/amfs_generic.c
diff --git a/amd/amd.h b/amd/amd.h
index f66f5b7..504bcf7 100644
--- a/amd/amd.h
+++ b/amd/amd.h
@@ -112,6 +112,7 @@
#define AMF_AUTOFS 0x0004 /* This node is part of an autofs filesystem */
#define AMF_REMOUNT 0x0008 /* This node needs to be remounted */
#define AMF_SOFTLOOKUP 0x0010 /* This node returns EIO if server is down */
+#define AMF_SOFTUNMOUNT 0x0020 /* unmount_node() returned EAGAIN, mount still referenced */
/*
* macros for struct mntfs (list of mounted filesystems)
diff --git a/amd/amfs_generic.c b/amd/amfs_generic.c
index 86d0ab7..7ab2829 100644
--- a/amd/amfs_generic.c
+++ b/amd/amfs_generic.c
@@ -178,7 +178,7 @@ amfs_lookup_node(am_node *mp, char *fname, int *error_return)
error = mf->mf_error;
continue;
}
- if (!(mf->mf_flags & MFF_MOUNTED) || (mf->mf_flags & MFF_UNMOUNTING)) {
+ if (mf->mf_flags & (MFF_MOUNTING | MFF_UNMOUNTING)) {
in_progrss:
/*
* If the fs is not mounted or it is unmounting then there
@@ -743,9 +743,13 @@ amfs_bgmount(struct continuation *cp)
if (mf->mf_flags & (MFF_MOUNTING | MFF_UNMOUNTING)) {
@ -38,18 +59,65 @@ Signed-off-by: Ian Kent <raven@themaw.net>
goto retry;
}
--- am-utils-6.2.orig/amd/autil.c
+++ am-utils-6.2/amd/autil.c
@@ -703,6 +703,12 @@ am_unmounted(am_node *mp)
diff --git a/amd/autil.c b/amd/autil.c
index f44a0e2..1962c71 100644
--- a/amd/autil.c
+++ b/amd/autil.c
@@ -703,6 +703,15 @@ am_unmounted(am_node *mp)
}
/*
+ * Clear the mounted flag in case there is a pending mount with
+ * the same target fs.
+ * the same target fs and this is the last reference to it.
+ */
+ mf->mf_flags &= ~MFF_MOUNTED;
+ if (mp->am_flags & AMF_SOFTUNMOUNT)
+ mp->am_flags &= ~AMF_SOFTUNMOUNT;
+ else
+ mf->mf_flags &= ~MFF_MOUNTED;
+
+ /*
* If this is a pseudo-directory then adjust the link count
* in the parent
*/
diff --git a/amd/map.c b/amd/map.c
index a6df44b..cf5263e 100644
--- a/amd/map.c
+++ b/amd/map.c
@@ -819,11 +819,17 @@ unmount_node(opaque_t arg)
#endif /* HAVE_FS_AUTOFS */
if (mf->mf_refc == 1)
error = mf->mf_ops->umount_fs(mp, mf);
+
+ /* Mount was not actually unmounted, soft umount.
+ * Tell the caller about it.
+ */
+ if (!error && mf->mf_refc > 1)
+ error = EAGAIN;
}
/* do this again, it might have changed */
mf = mp->am_al->al_mnt;
- if (error) {
+ if (error && error != EAGAIN) {
errno = error; /* XXX */
dlog("%s: unmount: %m", mf->mf_mount);
}
@@ -870,6 +876,10 @@ free_map_if_success(int rc, int term, opaque_t arg)
#endif /* HAVE_FS_AUTOFS */
amd_stats.d_uerr++;
} else if (rc) {
+ if (rc == EAGAIN) {
+ mp->am_flags |= AMF_SOFTUNMOUNT;
+ goto done;
+ }
notify_child(mp, AMQ_UMNT_FAILED, rc, 0);
if (mf->mf_ops == &amfs_program_ops || rc == EBUSY)
plog(XLOG_STATS, "\"%s\" on %s still active", mp->am_path, mf->mf_mount);
@@ -885,6 +895,7 @@ free_map_if_success(int rc, int term, opaque_t arg)
#endif /* HAVE_FS_AUTOFS */
amd_stats.d_uerr++;
} else {
+done:
/*
* am_unmounted() will call notify_child() appropriately.
*/

5
am-utils.spec
View File

@ -2,7 +2,7 @@ Summary: Automount utilities including an updated version of Amd
Name: am-utils
Version: 6.2.0
%define upstream_version 6.2
Release: 22%{?dist}
Release: 23%{?dist}
License: BSD
Epoch: 5
Group: System Environment/Daemons
@ -251,6 +251,9 @@ fi
%{_libdir}/libamu.so*
%changelog
* Thu Dec 1 2016 Ian Kent <ikent@redhat.com> - 5:6.2.0-23
- fix fix-umount-to-mount-race patch (bug 1399213).
* Mon Oct 3 2016 Ian Kent <ikent@redhat.com> - 5:6.2.0-22
- fix ambiguous else due to dlog() macro usage.