The patch titled
vfs: add MS_BIND_FLAGS mount flag
has been added to the -mm tree. Its filename is
vfs-add-ms_bind_flags-mount-flag.patch
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*** 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
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: vfs: add MS_BIND_FLAGS mount flag
From: Paul Menage <menage@xxxxxxxxxx>
Add a new mount() flag, MS_BIND_FLAGS.
MS_BIND_FLAGS indicates that a bind mount should take its per-mount flags
from the arguments passed to mount() rather than from the source
mountpoint.
This flag allows you to create a bind mount with the desired per-mount
flags in a single operation, rather than having to do a bind mount followed
by a remount, which is fiddly and can block for non-trivial periods of time
(on sb->s_umount?).
For recursive bind mounts, only the root of the tree being bound inherits
the per-mount flags from the mount() arguments; sub-mounts inherit their
per-mount flags from the source tree as usual.
Signed-off-by: Paul Menage <menage@xxxxxxxxxx>
Cc: Ram Pai <linuxram@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: Dave Hansen <haveblue@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 37 +++++++++++++++++++++++++------------
include/linux/fs.h | 2 ++
2 files changed, 27 insertions(+), 12 deletions(-)
diff -puN fs/namespace.c~vfs-add-ms_bind_flags-mount-flag fs/namespace.c
--- a/fs/namespace.c~vfs-add-ms_bind_flags-mount-flag
+++ a/fs/namespace.c
@@ -512,13 +512,13 @@ static struct vfsmount *skip_mnt_tree(st
}
static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
- int flag)
+ int flag, int mnt_flags)
{
struct super_block *sb = old->mnt_sb;
struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
if (mnt) {
- mnt->mnt_flags = old->mnt_flags;
+ mnt->mnt_flags = mnt_flags;
atomic_inc(&sb->s_active);
mnt->mnt_sb = sb;
mnt->mnt_root = dget(root);
@@ -1095,8 +1095,9 @@ static int lives_below_in_same_fs(struct
}
}
-struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
- int flag)
+static struct vfsmount *
+__copy_tree(struct vfsmount *mnt, struct dentry *dentry,
+ int flag, int mnt_flags)
{
struct vfsmount *res, *p, *q, *r, *s;
struct nameidata nd;
@@ -1104,7 +1105,7 @@ struct vfsmount *copy_tree(struct vfsmou
if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
return NULL;
- res = q = clone_mnt(mnt, dentry, flag);
+ res = q = clone_mnt(mnt, dentry, flag, mnt_flags);
if (!q)
goto Enomem;
q->mnt_mountpoint = mnt->mnt_mountpoint;
@@ -1126,7 +1127,7 @@ struct vfsmount *copy_tree(struct vfsmou
p = s;
nd.path.mnt = q;
nd.path.dentry = p->mnt_mountpoint;
- q = clone_mnt(p, p->mnt_root, flag);
+ q = clone_mnt(p, p->mnt_root, flag, p->mnt_flags);
if (!q)
goto Enomem;
spin_lock(&vfsmount_lock);
@@ -1146,6 +1147,11 @@ Enomem:
}
return NULL;
}
+struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
+ int flag)
+{
+ return __copy_tree(mnt, dentry, flag, mnt->mnt_flags);
+}
struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)
{
@@ -1322,8 +1328,8 @@ static noinline int do_change_type(struc
* do loopback mount.
* noinline this do_mount helper to save do_mount stack space.
*/
-static noinline int do_loopback(struct nameidata *nd, char *old_name,
- int recurse)
+static noinline int do_loopback(struct nameidata *nd, char *old_name, int flags,
+ int mnt_flags)
{
struct nameidata old_nd;
struct vfsmount *mnt = NULL;
@@ -1345,10 +1351,15 @@ static noinline int do_loopback(struct n
goto out;
err = -ENOMEM;
- if (recurse)
- mnt = copy_tree(old_nd.path.mnt, old_nd.path.dentry, 0);
+ /* Use the source mount flags unless the user passed MS_BIND_FLAGS */
+ if (!(flags & MS_BIND_FLAGS))
+ mnt_flags = old_nd.path.mnt->mnt_flags;
+ if (flags & MS_REC)
+ mnt = __copy_tree(old_nd.path.mnt, old_nd.path.dentry, 0,
+ mnt_flags);
else
- mnt = clone_mnt(old_nd.path.mnt, old_nd.path.dentry, 0);
+ mnt = clone_mnt(old_nd.path.mnt, old_nd.path.dentry, 0,
+ mnt_flags);
if (!mnt)
goto out;
@@ -1882,7 +1893,9 @@ long do_mount(char *dev_name, char *dir_
retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags,
data_page);
else if (flags & MS_BIND)
- retval = do_loopback(&nd, dev_name, flags & MS_REC);
+ retval = do_loopback(&nd, dev_name,
+ flags & (MS_REC | MS_BIND_FLAGS),
+ mnt_flags);
else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
retval = do_change_type(&nd, flags);
else if (flags & MS_MOVE)
diff -puN include/linux/fs.h~vfs-add-ms_bind_flags-mount-flag include/linux/fs.h
--- a/include/linux/fs.h~vfs-add-ms_bind_flags-mount-flag
+++ a/include/linux/fs.h
@@ -125,6 +125,8 @@ extern int dir_notify_enable;
#define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */
#define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */
#define MS_I_VERSION (1<<23) /* Update inode I_version field */
+#define MS_BIND_FLAGS (1<<24) /* For MS_BIND, take mnt_flags from
+ * args, not from source mountpoint */
#define MS_ACTIVE (1<<30)
#define MS_NOUSER (1<<31)
_
Patches currently in -mm which might be from menage@xxxxxxxxxx are
vfs-add-ms_bind_flags-mount-flag.patch
add-a-refcount-check-in-dput.patch
-
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