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Message-Id: <20080429185947.BB8609C2@kernel>
Date: Tue, 29 Apr 2008 11:59:47 -0700
From: Dave Hansen <dave@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, viro@...iv.linux.org.uk,
hch@...radead.org, trond.myklebust@....uio.no,
Dave Hansen <dave@...ux.vnet.ibm.com>
Subject: [RFC][PATCH 3/5] reintroduce list of vfsmounts over superblock
We're moving a big chunk of the burden of keeping people from
writing to r/o filesystems from the superblock into the
vfsmount. This requires that we consult the superblock's
vfsmounts when things like remounts occur.
So, introduce a list of vfsmounts hanging off the superblock.
We'll use this in a bit.
Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com>
---
linux-2.6.git-dave/fs/namespace.c | 12 ++++++++++++
linux-2.6.git-dave/fs/super.c | 1 +
linux-2.6.git-dave/include/linux/fs.h | 1 +
linux-2.6.git-dave/include/linux/mount.h | 1 +
4 files changed, 15 insertions(+)
diff -puN fs/namespace.c~reintroduce_list_of_vfsmounts_over_superblock fs/namespace.c
--- linux-2.6.git/fs/namespace.c~reintroduce_list_of_vfsmounts_over_superblock 2008-04-29 11:56:40.000000000 -0700
+++ linux-2.6.git-dave/fs/namespace.c 2008-04-29 11:56:40.000000000 -0700
@@ -402,6 +402,13 @@ static void __mnt_unmake_readonly(struct
spin_unlock(&vfsmount_lock);
}
+void add_mount_to_sb_list(struct vfsmount *mnt, struct super_block *sb)
+{
+ spin_lock(&vfsmount_lock);
+ list_add(&mnt->mnt_sb_list, &sb->s_vfsmounts);
+ spin_unlock(&vfsmount_lock);
+}
+
int simple_set_mnt_no_get(struct vfsmount *mnt, struct super_block *sb)
{
mnt->mnt_sb = sb;
@@ -420,6 +427,10 @@ EXPORT_SYMBOL(simple_set_mnt);
void free_vfsmnt(struct vfsmount *mnt)
{
+ spin_lock(&vfsmount_lock);
+ if (mnt->mnt_sb)
+ list_del(&mnt->mnt_sb_list);
+ spin_unlock(&vfsmount_lock);
kfree(mnt->mnt_devname);
mnt_free_id(mnt);
kmem_cache_free(mnt_cache, mnt);
@@ -585,6 +596,7 @@ static struct vfsmount *clone_mnt(struct
mnt->mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
+ add_mount_to_sb_list(mnt, sb);
if (flag & CL_SLAVE) {
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
diff -puN fs/super.c~reintroduce_list_of_vfsmounts_over_superblock fs/super.c
--- linux-2.6.git/fs/super.c~reintroduce_list_of_vfsmounts_over_superblock 2008-04-29 11:56:40.000000000 -0700
+++ linux-2.6.git-dave/fs/super.c 2008-04-29 11:56:40.000000000 -0700
@@ -67,6 +67,7 @@ static struct super_block *alloc_super(s
INIT_LIST_HEAD(&s->s_io);
INIT_LIST_HEAD(&s->s_more_io);
INIT_LIST_HEAD(&s->s_files);
+ INIT_LIST_HEAD(&s->s_vfsmounts);
INIT_LIST_HEAD(&s->s_instances);
INIT_HLIST_HEAD(&s->s_anon);
INIT_LIST_HEAD(&s->s_inodes);
diff -puN include/linux/fs.h~reintroduce_list_of_vfsmounts_over_superblock include/linux/fs.h
--- linux-2.6.git/include/linux/fs.h~reintroduce_list_of_vfsmounts_over_superblock 2008-04-29 11:56:40.000000000 -0700
+++ linux-2.6.git-dave/include/linux/fs.h 2008-04-29 11:56:40.000000000 -0700
@@ -1058,6 +1058,7 @@ struct super_block {
struct list_head s_io; /* parked for writeback */
struct list_head s_more_io; /* parked for more writeback */
struct hlist_head s_anon; /* anonymous dentries for (nfs) exporting */
+ struct list_head s_vfsmounts;
struct list_head s_files;
struct block_device *s_bdev;
diff -puN include/linux/mount.h~reintroduce_list_of_vfsmounts_over_superblock include/linux/mount.h
--- linux-2.6.git/include/linux/mount.h~reintroduce_list_of_vfsmounts_over_superblock 2008-04-29 11:56:40.000000000 -0700
+++ linux-2.6.git-dave/include/linux/mount.h 2008-04-29 11:56:40.000000000 -0700
@@ -44,6 +44,7 @@ struct vfsmount {
struct dentry *mnt_mountpoint; /* dentry of mountpoint */
struct dentry *mnt_root; /* root of the mounted tree */
struct super_block *mnt_sb; /* pointer to superblock */
+ struct list_head mnt_sb_list; /* list of all mounts on same sb */
struct list_head mnt_mounts; /* list of children, anchored here */
struct list_head mnt_child; /* and going through their mnt_child */
int mnt_flags;
_
--
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