On Fri, 15 Jan 2010, Karel Zak wrote:
>
> BTW, you can call
>
> blkid -o udev -p -u filesystem /dev/snail
Doesn't help much at all:
[root@EeePC torvalds]# time blkid -o udev -p -u filesystem /dev/sdc1
ID_FS_SEC_TYPE=msdos
ID_FS_VERSION=FAT12
ID_FS_TYPE=vfat
ID_FS_USAGE=filesystem
real 0m9.233s
user 0m0.003s
sys 0m0.003s
because it still does that large read:
read(3, "\353<\220){'`jIHC\0\2\10\1\0\2\0\2\333\3\370\1\0?\0\377\0 \0\0\0"..., 69632) = 69632
(but then it does _not_ do the 15+ small reads at the end).
It still does two other reads:
_llseek(3, 270336, [270336], SEEK_SET) = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1024) = 1024
_llseek(3, 262144, [262144], SEEK_SET) = 0
read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1377) = 1377
I dunno what those are about. It's at about the middle of the disk. Might
be some vfat tables.
> or -u noraid
Same thing. "-u noraid" seems to do exactly the same reads and seeks as
"-u filesystem".
> the other way is to use -S <size> to restrict probing
> area. (Unfortunately, it seems that -S doesn't work now, I'll fix it
> asap.)
Well, I'd have to restrict it to the first few kB of the device to get rid
of that insane 70kB read.
You can definitely find a FAT12 filesystem in way less than 70kB.
Linus
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