Step1:First Launch the emulator
Step 2:Type a command like adb shell, now u r in adb shell.
Step 3:Type # mount and enter
Show the list of folders (mount folder) or we can say file system
Output like below
rootfs / rootfs ro 0 0
tmpfs /dev tmpfs rw,mode=755 0 0
devpts /dev/pts devpts rw,mode=600 0 0
proc /proc proc rw 0 0
sysfs /sys sysfs rw 0 0
tmpfs /sqlite_stmt_journals tmpfs rw,size=4096k 0 0
/dev/block/mtdblock0 /system yaffs2 ro 0 0
/dev/block/mtdblock1 /data yaffs2 rw,nosuid,nodev 0 0
/dev/block/mtdblock2 /cache yaffs2 rw,nosuid,nodev 0 0
Step 4:# mount -o rw,remount -t yaffs2 /dev/block/mtdblock1 /data
Note: Replace /dev/block/mtdblock1 & /data with appropriate device path and mount point