On 19/04/10 12:20 PM, Greg Freemyer wrote:
Adding Mark Lord in cc.
..
On Mon, Apr 19, 2010 at 6:55 AM, Lukas Czerner<lczerner@xxxxxxxxxx> wrote:
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The basic idea behind my discard support is to create an ioctl which walks through all the free extents in each allocating group and discard those extents. As an addition to improve its performance one can specify minimum free extent length, so ioctl will not bother with shorter extents.
.. Perfect. I proposed exactly this last year, but never found time to work it further. Please proceed with it! ..
But you may notice, that there is one problem. bb_bitmap_deleted does not survive umount. To bypass the problem the first ioctl call have to walk through whole file system trimming all free extents. But there is a better solution to this problem. The bb_bitmap_deleted can be stored on disk an can be restored in mount time along with other bitmaps, but I think it is a quite big change and should be discussed further.
.. That's not necessary. It is a simple matter to TRIM a clean filesystem before it is mounted R/W during the boot sequence. No new information is required for that operation. My wiper.sh script already shows walking the freelists and trimming all available space, something which takes only a couple of seconds on a 120GB filesystem that has not been kept up-to-date with on-the-fly trim. Cheers -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
