On Thu, Jan 14, 2010 at 04:28:11PM -0800, Linus Torvalds wrote:
> - maybe blkid could be improved to not be such a pig. Even if you don't
> have a really slow device like mine, I bet people could see some of the
> same issues with a USB floppy drive.
Fixed. Changes:
("small device" = 1024*1440 bytes)
- don't ignore size in blkid_probe_set_device() (-S option)
- ignore extremely small devices (<= 1024 bytes, e.g. extended partitions)
- don't use safe probing for small devices
- don't probe for RAIDs on small devices
- don't read the begin (69kB) of the device by one large read()
- fill in the SB buffer dynamically
- use extra buffer for FATs root dir entries (FAT FS label)
on small devices to avoid large reads
You needn't any extra option or spacial udev rule. Everything works
by default.
For example FAT12 on a small device:
Old version:
$ strace -e read blkid -p floppy.img 2>&1 | \
awk -F ' = ' 'BEGIN {x=0} /read/ && !/.*ELF/ {x += $2} END { print x }'
73292
New version:
$ strace -e read blkid -p floppy.img 2>&1 | \
awk -F ' = ' 'BEGIN {x=0} /read/ && !/.*ELF/ {x += $2} END { print x }'
8192
I think 8192 bytes is not so bad.
Linus, if you want to test it:
git clone git://git.kernel.org/pub/scm/utils/util-linux-ng/util-linux-ng.git
cd util-linux-ng
./autogen.sh
./configure
make -C shlibs/blkid/src/
make -C misc-utils/ blkid
misc-utils/blkid -p /dev/sdc1
... or I can add a test rpm package to Fedora testing repository.
What version of Fedora are you running on the machine?
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
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