Re: Mounting block device fails.

On Thu, Oct 8, 2009 at 12:38 PM, Prasad Joshi <[email protected]> wrote:
> Hi,
>
> I am working on translation layer for flash. For the purpose testing I am
> using a disk file to simulate the flash behavior. So every read and write on
> the block device finally goes to a disk file, something similar to loop
> device, but in addition maintaining the flash property.
>
> I am able to create the file system on the device (/dev/ftl) but when I try
> to mount the device it fails with error "Invalid Argument".

From the code I can see -EINVAL can be returned at lot of places. You
need to see dmesg to see the message which can help tracing.

>
> I thought it is failing to read the super block of the file systems, but it
> seems like it did not fail in superblock read
>
> # strace -o out mount -t ext2 /dev/ftl /mntpt/
> [  175.192033] Opening the device.
> [  175.193599] IftlIoRead: offset=0x400 Length=0x400
> [  175.193875] OffsetWithinPage: 400
> [  175.195104] Read pos=1002535424, length=8192
> [  175.195474] 0000 0001 0000 0004 3333 0000 eea5 0003 fff5 0000 0000 0000
> 0002 0000 0002 0000 8000 0000 8000 0000 2000 0000 0000 0000 8a9e 4acd 0000
> 0020 ef53 0001 0001 0000 8a9e 4acd 4e00 00ed 0000 0000 0001 0000 0000 0000
> 000b 0000 0100 0000 0038 0000 0002 0000 0003 0000 a037 8e0c d6b3 de11 abb8
> 0635 bff9 2b36 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
> 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
> 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
> 0000 003f 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
> 0000 a037 8f0c d6b3 de11 abb8 0635 bff9 2b36 0001 0000 0000 0000 0000 0000
> 8a9e 4acd 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
> 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
> 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 001c 001c 0001
> 0000 0000 0000 0000 0000 0000 0000 0000 0000 [  175.215929] Closing the
> device.
> mount: mounting /dev/ftl on /mntpt/ failed: Invalid argument
>
> I tried printing the data in hex format just to make sure proper ext2 magic
> code in present in the superblock read from the flash device.  "ef53" is the
> magic code of ext2 superblock, ftl device is correctly reading the magic
> code
>
> # cat out
> execve("/bin/mount", ["mount", "-t", "ext2", "/dev/ftl", "/mntpt/"], [/* 4
> vars */]) = 0
> uname({sys="Linux", node="(none)", ...}) = 0
> brk(0)                                  = 0x72f000
> brk(0x72ff40)                           = 0x72ff40
> arch_prctl(ARCH_SET_FS, 0x72f880)       = 0
> open("/dev/urandom", O_RDONLY)          = -1 ENOENT (No such file or
> directory)
> brk(0x750f40)                           = 0x750f40
> brk(0x751000)                           = 0x751000
> getuid()                                = 0
> getuid()                                = 0
> geteuid()                               = 0
> stat("/dev/ftl", {st_mode=S_IFBLK|0644, st_rdev=makedev(254, 0), ...}) = 0
> mount("/dev/ftl", "/mntpt/", "ext2", MS_SILENT, "") = -1 EINVAL (Invalid
> argument)
> vfork()                                 = 869
> --- SIGCHLD (Child exited) @ 0 (0) ---
> write(2, "mount: mounting /dev/ftl on /mntp"..., 61) = 61
> exit_group(-1)                          = ?
>
> What could be the reason of failure of mount?
>
> Thanks and Regards,
> Prasad
>
>



-- 
Thanks -
Manish
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