Messages in this thread | | | From | Matthew Geier <> | Subject | Re: write access to read-only mounted device, uhh | Date | Sun, 10 Jan 1999 09:55:01 +1100 (EST) |
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> When trying to hunt a bug in dmsdos, I ran into a problem with the FAT > driver. Well, meanwhile I think this is not a problem of the FAT driver, > but may be a more general problem, probably affecting other filesystems, > too. It seems, that under some circumstances, the FAT driver or something > at a higher level (probably VFS) can write to a device though it is mounted > read-only. > This might explain how I managed to corrupt the FAT file system on compact fash card. I use a Laptop running RH 5.2 linux to read the flash cards from my camera. I have a 16meg card and a 4 Meg card. I mount the flash cards read only, I delete the picture files back on the camera.
Well recently I ejected the 16meg card and inserted the 4meg card with out umounting the device first. The system got a little upset when I tried to list the directory, with all sorts of errors. Then I realised my error and removed the card and umounted the file system. However the 4 meg card's FAT file system was rather worse for wear afterward, and I lost several unsaved photos as a result. I for one was rather confused how a 'disk' mounted read only appeared to be modified by the system. (The flash cards emulate an ATA harddisk - Linux/PCMCIA Card Services treat them like hard disks...)
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