Messages in this thread |  | | Date | Wed, 13 Sep 2000 00:01:50 -0400 | Subject | Re: Bug in block device read/write! | From | tytso@mit ... |
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Date: Fri, 08 Sep 2000 03:41:27 +0100 From: Anton Altaparmakov <aia21@cam.ac.uk>
I have been trying to get the linear md driver to work with NTFS volumes for several months and it never worked. - I was suspecting the NTFS driver (after having fixed linear md and verified that at least that worked fine) but today I finally found why it doesn't work:
There is a bug in reading/writing to block devices. - It manifests itself in the form that partitions are too small by exactly one sector!
Even though a cfdisk shows that a partition has a certain number of sectors, you can never seek + read and/or write to the last sector (doing file i/o using read/write(2) [also tried fread/fwrite(3), same result]. - Last sector doesn't seem to exist. However reading the actual hd (/dev/hdb or /dev/sda, ie. affects both IDE and SCSI) instead of the partition (/dev/hdb7 or whatever) the sector does exist and contains the expected information!
This isn't a bug. The last sector is used by the md device to store the md superblock.
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