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Consider a scenario when 'vfs_link(dirA/fileA)' and 'vfs_unlink(dirA/fileA, dirB/fileB)' race. 'vfs_link()' does not lock 'dirA->i_mutex', so this is possible. Both of the functions lock 'fileA->i_mutex' though. Suppose 'vfs_unlink()' wins, and takes 'fileA->i_mutex' mutex first. Suppose 'fileA->i_nlink' is 1. In this case 'ubifs_unlink()' will drop the last reference, and put 'inodeA' to the list of orphans. After this, 'vfs_link()' will link 'dirB/fileB' to 'inodeA'. Thir is a problem because, for example, the subsequent 'vfs_unlink(dirB/fileB)' will add the same inode to the list of orphans. This problem was reported by J. R. Okajima <hooanon05@yahoo.co.jp> [Artem: add more comments, amended commit message] Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>