The umount_end operation allows cleaning of state set by umount_begin in
the event the filesystem doesn't actually get unmounted.
Signed-off-by: Joshua Watt <JPEWhacker@xxxxxxxxx>
---
fs/namespace.c | 22 ++++++++++++++++++++--
include/linux/fs.h | 1 +
2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index d18deb4c410b..d2587be4d08b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1524,6 +1524,12 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
}
}
+static void umount_end(struct super_block *sb, int flags)
+{
+ if (flags & MNT_FORCE && sb->s_op->umount_end)
+ sb->s_op->umount_end(sb);
+}
+
static void shrink_submounts(struct mount *mnt);
static int do_umount(struct mount *mnt, int flags)
@@ -1589,12 +1595,16 @@ static int do_umount(struct mount *mnt, int flags)
* Special case for "unmounting" root ...
* we just try to remount it readonly.
*/
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
+ if (!capable(CAP_SYS_ADMIN)) {
+ retval = -EPERM;
+ goto out_umount_end;
+ }
down_write(&sb->s_umount);
if (!sb_rdonly(sb))
retval = do_remount_sb(sb, SB_RDONLY, NULL, 0);
up_write(&sb->s_umount);
+ /* Still mounted. Always invoke the cleanup */
+ umount_end(sb, flags);
return retval;
}
@@ -1617,6 +1627,14 @@ static int do_umount(struct mount *mnt, int flags)
}
unlock_mount_hash();
namespace_unlock();
+
+out_umount_end:
+ /* If the umount failed and the file system is still mounted, allow the
+ * driver to cleanup any state it may have setup in umount_begin(). Note
+ * that this is purposely *not* called when MNT_DETACH is specified.
+ */
+ if (retval)
+ umount_end(sb, flags);
return retval;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 885266aae2d7..5443c22da18f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1816,6 +1816,7 @@ struct super_operations {
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
void (*umount_begin) (struct super_block *);
+ void (*umount_end)(struct super_block *);
int (*show_options)(struct seq_file *, struct dentry *);
int (*show_devname)(struct seq_file *, struct dentry *);
--
2.13.6
--
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