Thanks Arjan for clearing it about SG. I think i am fine with the
page_address() for now.
I managed to finish my virtual scsi device driver. Everything seems to
be working fine (Reading, writing , etc). But i can not mount a file
system created on it. From my verification, the driver seems to be doing
its job. I verified the read and write to the disk by partitioning the
device, using dd, etc. Seems to work fine. But i can not mount the file
system created on it.
(I am sorry if i am taking too much of your time and posting wrong
questions in the mailing list. Please guide me on this, this is the only
mailing list which responded to my question. I am not a professional
kernel developer and this is not my full time job but rather just a hobby).
I attached the outputs below, can some one advice what could be wrong here?
I partitioned the drive as follows. Please not that it shows one head, 8
sectors. I am not sure where it is getting this info. (I do not see any
SCSI commands issued to the driver for MODE_SENSE for disk geometry page).
[root@localhost scsitap]# fdisk -l /dev/sdb
Disk /dev/sdb: 104 MB, 104858112 bytes
1 heads, 8 sectors/track, 25600 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 2 21975 87896 83 Linux
[root@localhost scsitap]# mkfs /dev/sdb1
mke2fs 1.37 (21-Mar-2005)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
22000 inodes, 87896 blocks
4394 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
11 block groups
8192 blocks per group, 8192 fragments per group
2000 inodes per group
Superblock backups stored on blocks:
8193, 24577, 40961, 57345, 73729
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost scsitap]# mount -o ro /dev/sdb1 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
missing codepage or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
EXT2-fs error (device sdb1): ext2_check_descriptors: Block bitmap for
group 0 not in group (block 0)!
EXT2-fs: group descriptors corrupted!
Aboo
Arjan van de Ven wrote:
[note: you forgot to put in a link to your sourcecode, which greatly
reduces our ability to give you good answers; please fix this]
1. In 2.6 kernel, even if I set the sg_tablesize to SG_NONE, the
mid-layer is still queuing commands with use_sg=1. There is no way to
disable this SG at all?
in 2.6 everything is now going via the ONE sg codepath yes. The dual
code path stuff was just incredibly fragile and a bad idea.
address=page_address(sg[i].page) + sg[i].offset;
Is this the right way? I am assuming that sg[i].page will be mapped in
to kernel address space as this address is created by SCSI mid-layer. Is
that right? Or do I have to use kmap? I tried replacing page_address
with kmap/kunmap. But as soon as call kunmap to unmap, the kernal
panics! Any thoughts?
kmap doesn't take struct page as argument.
but.... if you show us the real code we can give you better
suggestions.
3. Do I have to disable bottom halves before calling scsi_done()? It
seems that the kernel panics when I call scsi_done if I use spin_lock
instead of spin_lock_bh(). This is one of my spin_locks created for
protecting a data structure.
you don't need any locks before calling the done method.
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