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vfs: fix freeze protection in mnt_want_write_file() for overlayfs

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[ Upstream commit a6795a585929d94ca3e931bc8518f8deb8bbe627 ]

The underlying real file used by overlayfs still contains the overlay path.
This results in mnt_want_write_file() calls by the filesystem getting
freeze protection on the wrong inode (the overlayfs one instead of the real
one).

Fix by using file_inode(file)->i_sb instead of file->f_path.mnt->mnt_sb.

Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miklos Szeredi 2018-07-18 15:44:43 +02:00 committed by Greg Kroah-Hartman
parent b888dba2e8
commit 4f4374a9bd
1 changed files with 4 additions and 3 deletions
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7
fs/namespace.c
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@ -446,10 +446,10 @@ int mnt_want_write_file_path(struct file *file)
{
int ret;
sb_start_write(file->f_path.mnt->mnt_sb);
sb_start_write(file_inode(file)->i_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file->f_path.mnt->mnt_sb);
sb_end_write(file_inode(file)->i_sb);
return ret;
}
@ -540,7 +540,8 @@ void __mnt_drop_write_file(struct file *file)
void mnt_drop_write_file_path(struct file *file)
{
mnt_drop_write(file->f_path.mnt);
__mnt_drop_write_file(file);
sb_end_write(file_inode(file)->i_sb);
}
void mnt_drop_write_file(struct file *file)