Storage space is decreased for a mouted read-only root file system
I use the U-boot (v1.3.4) to boot the Linux kernel (v2.6.14) with a jffs2 file system (stored in the FLASH). The bootargs is inputted as below:
bootargs root=/dev/mtdblock0 ro rootfstype=jffs2 mtdparts=phys_mapped_flash:128M(root)
After booting this system several times, I found the stroage space of mounted read-only file system is descreased. The descrease is not happend quickly. But, for a period of 4~5 days, the space would be descreased about 0.7~1MB. I used the 'df' command to observe this.
Because I had mounted the root file system as read only, why is the storage space descreased? Does any one could show any idea with me? Thanks a lot.