1 files changed, 17 insertions, 102 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index bd2f4c68506a..99186556f8d3 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -61,9 +61,6 @@ __setup("mphash_entries=", set_mphash_entries);
 static u64 event;
 static DEFINE_IDA(mnt_id_ida);
 static DEFINE_IDA(mnt_group_ida);
-static DEFINE_SPINLOCK(mnt_id_lock);
-static int mnt_id_start = 0;
-static int mnt_group_start = 1;
 
 static struct hlist_head *mount_hashtable __read_mostly;
 static struct hlist_head *mountpoint_hashtable __read_mostly;
@@ -101,50 +98,30 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry)
 
 static int mnt_alloc_id(struct mount *mnt)
 {
-	int res;
+	int res = ida_alloc(&mnt_id_ida, GFP_KERNEL);
 
-retry:
-	ida_pre_get(&mnt_id_ida, GFP_KERNEL);
-	spin_lock(&mnt_id_lock);
-	res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
-	if (!res)
-		mnt_id_start = mnt->mnt_id + 1;
-	spin_unlock(&mnt_id_lock);
-	if (res == -EAGAIN)
-		goto retry;
-
-	return res;
+	if (res < 0)
+		return res;
+	mnt->mnt_id = res;
+	return 0;
 }
 
 static void mnt_free_id(struct mount *mnt)
 {
-	int id = mnt->mnt_id;
-	spin_lock(&mnt_id_lock);
-	ida_remove(&mnt_id_ida, id);
-	if (mnt_id_start > id)
-		mnt_id_start = id;
-	spin_unlock(&mnt_id_lock);
+	ida_free(&mnt_id_ida, mnt->mnt_id);
 }
 
 /*
  * Allocate a new peer group ID
- *
- * mnt_group_ida is protected by namespace_sem
  */
 static int mnt_alloc_group_id(struct mount *mnt)
 {
-	int res;
+	int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL);
 
-	if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
-		return -ENOMEM;
-
-	res = ida_get_new_above(&mnt_group_ida,
-				mnt_group_start,
-				&mnt->mnt_group_id);
-	if (!res)
-		mnt_group_start = mnt->mnt_group_id + 1;
-
-	return res;
+	if (res < 0)
+		return res;
+	mnt->mnt_group_id = res;
+	return 0;
 }
 
 /*
@@ -152,10 +129,7 @@ static int mnt_alloc_group_id(struct mount *mnt)
  */
 void mnt_release_group_id(struct mount *mnt)
 {
-	int id = mnt->mnt_group_id;
-	ida_remove(&mnt_group_ida, id);
-	if (mnt_group_start > id)
-		mnt_group_start = id;
+	ida_free(&mnt_group_ida, mnt->mnt_group_id);
 	mnt->mnt_group_id = 0;
 }
 
@@ -431,74 +405,20 @@ int __mnt_want_write_file(struct file *file)
 }
 
 /**
- * mnt_want_write_file_path - get write access to a file's mount
- * @file: the file who's mount on which to take a write
- *
- * This is like mnt_want_write, but it takes a file and can
- * do some optimisations if the file is open for write already
- *
- * Called by the vfs for cases when we have an open file at hand, but will do an
- * inode operation on it (important distinction for files opened on overlayfs,
- * since the file operations will come from the real underlying file, while
- * inode operations come from the overlay).
- */
-int mnt_want_write_file_path(struct file *file)
-{
-	int ret;
-
-	sb_start_write(file->f_path.mnt->mnt_sb);
-	ret = __mnt_want_write_file(file);
-	if (ret)
-		sb_end_write(file->f_path.mnt->mnt_sb);
-	return ret;
-}
-
-static inline int may_write_real(struct file *file)
-{
-	struct dentry *dentry = file->f_path.dentry;
-	struct dentry *upperdentry;
-
-	/* Writable file? */
-	if (file->f_mode & FMODE_WRITER)
-		return 0;
-
-	/* Not overlayfs? */
-	if (likely(!(dentry->d_flags & DCACHE_OP_REAL)))
-		return 0;
-
-	/* File refers to upper, writable layer? */
-	upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
-	if (upperdentry &&
-	    (file_inode(file) == d_inode(upperdentry) ||
-	     file_inode(file) == d_inode(dentry)))
-		return 0;
-
-	/* Lower layer: can't write to real file, sorry... */
-	return -EPERM;
-}
-
-/**
  * mnt_want_write_file - get write access to a file's mount
  * @file: the file who's mount on which to take a write
  *
  * This is like mnt_want_write, but it takes a file and can
  * do some optimisations if the file is open for write already
- *
- * Mostly called by filesystems from their ioctl operation before performing
- * modification.  On overlayfs this needs to check if the file is on a read-only
- * lower layer and deny access in that case.
  */
 int mnt_want_write_file(struct file *file)
 {
 	int ret;
 
-	ret = may_write_real(file);
-	if (!ret) {
-		sb_start_write(file_inode(file)->i_sb);
-		ret = __mnt_want_write_file(file);
-		if (ret)
-			sb_end_write(file_inode(file)->i_sb);
-	}
+	sb_start_write(file_inode(file)->i_sb);
+	ret = __mnt_want_write_file(file);
+	if (ret)
+		sb_end_write(file_inode(file)->i_sb);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(mnt_want_write_file);
@@ -538,14 +458,9 @@ void __mnt_drop_write_file(struct file *file)
 	__mnt_drop_write(file->f_path.mnt);
 }
 
-void mnt_drop_write_file_path(struct file *file)
-{
-	mnt_drop_write(file->f_path.mnt);
-}
-
 void mnt_drop_write_file(struct file *file)
 {
-	__mnt_drop_write(file->f_path.mnt);
+	__mnt_drop_write_file(file);
 	sb_end_write(file_inode(file)->i_sb);
 }
 EXPORT_SYMBOL(mnt_drop_write_file);