UPDATE: Rooting via Framaroot will only give you partial root access.. If you mount your system partition as RW, the phone will reboot.. IMO, if you dont need root, then wait for DoomLord to add Xperia M to his script..
I tried changing the vold.fstab file and ended up losing access to my ext sd card.. But I managed to return to stock rom again y flashing it via flashtool..
If you mess up your phone, dont panic.. im gonna post a tutorial soon how to restore back to stock rom
TUTORIAL - HOW TO RESTORE STOCK ROM (Link to original XDA post)
Step 1 -> Download FTF file for Xperia M - C1904 India from XDA from here .. Use the Mega Download manager as itll make the download process a little easier.. Ill upload the rom to my dropbox shortly for convenience
My Dropbox Link - here
Step 2 -> Download latest Flashtool from here.. Register an account first then download it..
As of today, the latest flashtool version is 6-2013..
Step 3 -> Install and run flashtool
Step 4 -> turn on USB debugging and unknown sources Connect your phone..Flash tool will automatically detect your device
If you get this error, its fine as Xperia M hasnt been added to the flashtool index.. you can still use this to flash and itll wont pose any problem..
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Step 5 -> Disconnect your phone, Turn it off.. Now press and hold Volume Down and then plug in your cable.. you will see windows install SEMC Flash drivers automatically..
Step 6 -> Click the lightning button on Flashtool, select flashmode, then browse where you kept your STOCK ROM downloaded from Mega..
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Step 7 -> Click Flash and keep your fingers crossed.. ABSOLUTELY DO NOT REMOVE YOUR CABLE AT THIS POINT !!!!!
Step 8 -> When it's finished, itll ask you to unplug your cable and start the phone.. Do so now and wait a couple of moments for the phone to start.. The first boot after a successful flash usually takes a lot longer...
Step 9 -> there you go, you just successfully flashed stock ROM