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#1 (**permalink**) 01-05-2008, 02:48 AM

Hi,

The file sys/filsys.h contains the format of a JFS file system. It
contains the structure superblock which hold s_logdev of type dev_t
(the device address of log). I would like to know where exactly
s_logdev is used. What happens to the system if the s_logdev does not
contain the correct device address?

The superblock structure contains another member called s_fmod of type
char. Is this member set only during mount and unmount operations or
anywhere else?

Thanks in advance,
Atoshi

#2 (**permalink**) 01-05-2008, 02:59 AM

Atoshi wrote:

> The file sys/filsys.h contains the format of a JFS file system. It
> contains the structure superblock which hold s_logdev of type dev_t
> (the device address of log). I would like to know where exactly
> s_logdev is used. What happens to the system if the s_logdev does not
> contain the correct device address?

The log device if used by the filesystem helper when mounting the
filesystem, and then afterwards by the filesystem itself IIRC. No log
device, no mount.

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Usage of s_logdev and s_fmod in the superblock structure in sys/filsys.h