vfs: prevent remount read-only if pending removes
If there are any inodes on the super block that have been unlinked
(i_nlink == 0) but have not yet been deleted then prevent the
remounting the super block read-only.
Reported-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index 98ebc78..7e6f2c9 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -449,6 +449,10 @@
struct mount *mnt;
int err = 0;
+ /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */
+ if (atomic_long_read(&sb->s_remove_count))
+ return -EBUSY;
+
br_write_lock(vfsmount_lock);
list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
if (!(mnt->mnt.mnt_flags & MNT_READONLY)) {
@@ -460,6 +464,9 @@
}
}
}
+ if (!err && atomic_long_read(&sb->s_remove_count))
+ err = -EBUSY;
+
if (!err) {
sb->s_readonly_remount = 1;
smp_wmb();