Hi, Here is another way of allowing sane access to file system specific information, statistics and configuration. It involves using the translation filesystem (http://trfs.sourceforge.net/). An example of filesystem configuration: configurable forcing data flush for all writes to files in a filesystem, is implemented and is available for download. It is implemented for ext2tr filesystem, which is ext2 filesystem with few modifications to use the translation filesystem. Filesystem views ---------------- Filesystem views give information about filesystems and allow users to configure them. Filesystem views for files and directories residing in the same filesystem are identical. They are applicable to the whole filesystem. An example filesystem view fs/config has been provided for ext2tr filesytem. This view can be used to configure the filesystem to immediately flush data written to files in the filesystem. Uses of filesystem views ----------------------- Filesystems can allow users to configure them through filesystem configuration views. Although ioctls can be used for the same purpose, using views is better. A comparison of ioctls and translation filesystem views is given on the translation filesystem webpage. A View that gives information for a filesystem can be put into the fs view at fs/info. The view can be instantiated into a directory which contains text files giving filesystem information. Filesystem statistics can be put into fs/stats. fs/config view can be used to configure a filesystem. Example of fs/config view ------------------------- The ext2tr filesystem (available from downloads page) contains an example translator for fs/config view. The view instantiates into a directory, which contains a file forcedsync. This file is used to control data sync behavior for an ext2tr filesystem. If forcedsync file contains a character 0, flags specified while opening a file in the filesystem are used to determine whether data written to the file is immediately flushed to disk. If forcedsync file contains a character 1, all data written to a file in the filesystem is immediately flushed to disk regardless of the flags specified while opening the file. Contents of the file can be checked by reading it and can be changed by writing to it. A usage of the view is shown below. In the example, dd command required 0.10 seconds when forcedsync was not enabled. After enabling forcedsync, dd command required 1.62 seconds because data was being flushed at each write system call. [root@localhost /root]# mkfs -t ext2 /dev/hda5 > /dev/null mke2fs 1.18, 11-Nov-1999 for EXT2 FS 0.5b, 95/08/09 [root@localhost /root]# mount -t ext2tr /dev/hda5 /mnt0 [root@localhost /root]# time dd if=/dev/zero of=/mnt0/foo bs=1024 count=100 100+0 records in 100+0 records out 0.00user 0.02system 0:00.10elapsed 18%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (116major+20minor)pagefaults 0swaps [root@localhost /root]# umount /mnt0 [root@localhost /root]# mkfs -t ext2 /dev/hda5 > /dev/null mke2fs 1.18, 11-Nov-1999 for EXT2 FS 0.5b, 95/08/09 [root@localhost /root]# mount -t ext2tr /dev/hda5 /mnt0 [root@localhost /root]# /home/amit/developement/trfs/cmds/vcmd/vcmd /mnt0 fs/config -c ls @1/ forcedsync [root@localhost /root]# /home/amit/developement/trfs/cmds/vcmd/vcmd /mnt0 fs/config -c cat @1/forcedsync [root@localhost /root]# echo 1 | /home/amit/developement/trfs/cmds/vcmd/vcmd /mnt0 fs/config -c dd of=@1/forcedsync bs=1 count=1 1+0 records in 1+0 records out [root@localhost /root]# /home/amit/developement/trfs/cmds/vcmd/vcmd /mnt0 fs/config -c cat @1/forcedsync [root@localhost /root]# time dd if=/dev/zero of=/mnt0/foo bs=1024 count=100 100+0 records in 100+0 records out 0.00user 0.01system 0:01.62elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (116major+20minor)pagefaults 0swaps -- Amit S. Kale <[EMAIL PROTECTED]> Linux kernel source level debugger http://kgdb.sourceforge.net/ Translation Filesystem http://trfs.sourceforge.net/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
