The patch titled
r/o bind mounts: honor r/w changes at do_remount() time
has been added to the -mm tree. Its filename is
r-o-bind-mounts-honor-r-w-changes-at-do_remount-time.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: r/o bind mounts: honor r/w changes at do_remount() time
From: Dave Hansen <haveblue@xxxxxxxxxx>
Originally from: Herbert Poetzl <herbert@xxxxxxxxxxxx>
This is the core of the read-only bind mount patch set.
Note that this does _not_ add a "ro" option directly to the bind mount
operation. If you require such a mount, you must first do the bind, then
follow it up with a 'mount -o remount,ro' operation.
Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 46 +++++++++++++++++++++++++++++++++++++++-------
1 file changed, 39 insertions(+), 7 deletions(-)
diff -puN fs/namespace.c~r-o-bind-mounts-honor-r-w-changes-at-do_remount-time fs/namespace.c
--- a/fs/namespace.c~r-o-bind-mounts-honor-r-w-changes-at-do_remount-time
+++ a/fs/namespace.c
@@ -105,7 +105,11 @@ struct vfsmount *alloc_vfsmnt(const char
*/
int __mnt_is_readonly(struct vfsmount *mnt)
{
- return (mnt->mnt_sb->s_flags & MS_RDONLY);
+ if (mnt->mnt_flags & MNT_READONLY)
+ return 1;
+ if (mnt->mnt_sb->s_flags & MS_RDONLY)
+ return 1;
+ return 0;
}
EXPORT_SYMBOL_GPL(__mnt_is_readonly);
@@ -278,7 +282,7 @@ void mnt_drop_write(struct vfsmount *mnt
}
EXPORT_SYMBOL_GPL(mnt_drop_write);
-int mnt_make_readonly(struct vfsmount *mnt)
+static int mnt_make_readonly(struct vfsmount *mnt)
{
int ret = 0;
@@ -291,15 +295,21 @@ int mnt_make_readonly(struct vfsmount *m
goto out;
}
/*
- * actually set mount's r/o flag here to make
- * __mnt_is_readonly() true, which keeps anyone
- * from doing a successful mnt_want_write().
+ * nobody can do a successful mnt_want_write() with all
+ * of the counts in MNT_DENIED_WRITE and the locks held.
*/
+ if (!ret)
+ mnt->mnt_flags |= MNT_READONLY;
out:
mnt_unlock_cpus();
return ret;
}
+static void __mnt_unmake_readonly(struct vfsmount *mnt)
+{
+ mnt->mnt_flags &= ~MNT_READONLY;
+}
+
int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
{
mnt->mnt_sb = sb;
@@ -679,7 +689,7 @@ static int show_vfsmnt(struct seq_file *
seq_putc(m, '.');
mangle(m, mnt->mnt_sb->s_subtype);
}
- seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
+ seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
if (mnt->mnt_sb->s_flags & fs_infop->flag)
seq_puts(m, fs_infop->str);
@@ -1311,6 +1321,23 @@ out:
return err;
}
+static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
+{
+ int error = 0;
+ int readonly_request = 0;
+
+ if (ms_flags & MS_RDONLY)
+ readonly_request = 1;
+ if (readonly_request == __mnt_is_readonly(mnt))
+ return 0;
+
+ if (readonly_request)
+ error = mnt_make_readonly(mnt);
+ else
+ __mnt_unmake_readonly(mnt);
+ return error;
+}
+
/*
* change filesystem flags. dir should be a physical root of filesystem.
* If you've mounted a non-root directory somewhere and want to do remount
@@ -1332,7 +1359,10 @@ static int do_remount(struct nameidata *
return -EINVAL;
down_write(&sb->s_umount);
- err = do_remount_sb(sb, flags, data, 0);
+ if (flags & MS_BIND)
+ err = change_mount_flags(nd->mnt, flags);
+ else
+ err = do_remount_sb(sb, flags, data, 0);
if (!err) {
clear_mnt_user(nd->mnt);
nd->mnt->mnt_flags = mnt_flags;
@@ -1832,6 +1862,8 @@ long do_mount(char *dev_name, char *dir_
mnt_flags |= MNT_RELATIME;
if (flags & MS_NOMNT)
mnt_flags |= MNT_NOMNT;
+ if (flags & MS_RDONLY)
+ mnt_flags |= MNT_READONLY;
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_NOMNT);
_
Patches currently in -mm which might be from haveblue@xxxxxxxxxx are
revert-gregkh-driver-warn-when-statically-allocated-kobjects-are-used.patch
make-kobject-dynamic-allocation-check-use-kallsyms_lookup.patch
generic-virtual-memmap-support-for-sparsemem-remove-excess-debugging.patch
generic-virtual-memmap-support-for-sparsemem-simplify-initialisation-code-and-reduce-duplication.patch
generic-virtual-memmap-support-for-sparsemem-pull-out-the-vmemmap-code-into-its-own-file.patch
ppc64-sparsemem_vmemmap-support-vmemmap-ppc64-convert-vmm_-macros-to-a-real-function.patch
r-o-bind-mounts-filesystem-helpers-for-custom-struct-files.patch
r-o-bind-mounts-rearrange-may_open-to-be-r-o-friendly.patch
r-o-bind-mounts-give-may_open-a-local-mnt-variable.patch
r-o-bind-mounts-create-cleanup-helper-svc_msnfs.patch
r-o-bind-mounts-stub-functions.patch
r-o-bind-mounts-elevate-write-count-opend-files.patch
r-o-bind-mounts-elevate-write-count-for-some-ioctls.patch
r-o-bind-mounts-elevate-writer-count-for-chown-and-friends.patch
r-o-bind-mounts-make-access-use-mnt-check.patch
r-o-bind-mounts-elevate-mnt-writers-for-callers-of-vfs_mkdir.patch
r-o-bind-mounts-elevate-write-count-during-entire-ncp_ioctl.patch
r-o-bind-mounts-elevate-write-count-for-link-and-symlink-calls.patch
r-o-bind-mounts-elevate-mount-count-for-extended-attributes.patch
r-o-bind-mounts-elevate-write-count-for-file_update_time.patch
r-o-bind-mounts-unix_find_other-elevate-write-count-for-touch_atime.patch
r-o-bind-mounts-elevate-write-count-over-calls-to-vfs_rename.patch
r-o-bind-mounts-nfs-check-mnt-instead-of-superblock-directly.patch
r-o-bind-mounts-elevate-writer-count-for-do_sys_truncate.patch
r-o-bind-mounts-elevate-write-count-for-do_utimes.patch
r-o-bind-mounts-elevate-write-count-for-do_sys_utime-and-touch_atime.patch
r-o-bind-mounts-sys_mknodat-elevate-write-count-for-vfs_mknod-create.patch
r-o-bind-mounts-elevate-mnt-writers-for-vfs_unlink-callers.patch
r-o-bind-mounts-do_rmdir-elevate-write-count.patch
r-o-bind-mounts-track-number-of-mount-writers.patch
r-o-bind-mounts-honor-r-w-changes-at-do_remount-time.patch
cpuset-zero-malloc-revert-the-old-cpuset-fix.patch
task-containersv11-basic-task-container-framework.patch
task-containersv11-add-tasks-file-interface.patch
task-containersv11-add-fork-exit-hooks.patch
task-containersv11-add-container_clone-interface.patch
task-containersv11-add-procfs-interface.patch
task-containersv11-shared-container-subsystem-group-arrays.patch
task-containersv11-automatic-userspace-notification-of-idle-containers.patch
task-containersv11-make-cpusets-a-client-of-containers.patch
task-containersv11-example-cpu-accounting-subsystem.patch
task-containersv11-simple-task-container-debug-info-subsystem.patch
pid-namespaces-define-and-use-task_active_pid_ns-wrapper.patch
pid-namespaces-rename-child_reaper-function.patch
pid-namespaces-use-task_pid-to-find-leaders-pid.patch
pid-namespaces-define-is_global_init-and-is_container_init.patch
pid-namespaces-define-is_global_init-and-is_container_init-versus-x86_64-mm-i386-show-unhandled-signals-v3.patch
pid-namespaces-move-alloc_pid-to-copy_process.patch
page-owner-tracking-leak-detector.patch
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