On Fri, 6 Aug 2010, Dmitry Monakhov wrote: > Lukas Czerner <lczerner@xxxxxxxxxx> writes: > > > Hi, all > > > > because people were worried about possibly long stalls appearing > > when FITRIM ioctl is working, I have changed the FITRIM interface > > as Dimitry suggested. Now you can choose whether to trim whole > > file system or just a part of it, resp. you can specify the range > > of Bytes to trim. > Agree with whole patch-set, except minor note for ext4'th path. > Please feel free to add > Reviewed-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> to the series > > The only thing what is still not obvious for me is that, there are > several types of discard request possible > 1) Simple discard > 2) Secure discard which was proposed here http://lkml.org/lkml/2010/6/24/71 > Should we specify which type should be used in ioctl flags? > But i hope that we can just stick maximum security scenario > Use secure discard if possible. First of all, thanks for you review Dimitry. And second, to be honest I am not entirely familiar with the Secure discard implementation. Right now it just doing the simple discard like "send TRIM command", so it does work just for devices which supports it. I suppose we can just check blk_queue_discard() at some level and then decide whether to do simple discard (TRIM), or secure discard "Write zeroes", when the device does not support TRIM - if it is what you mean by secure discard. Regards -Lukas > > > > To be specific you can create something like this: > > > > int main(int argc, char **argv) > > { > > int fd; > > uint64_t range[3]; > > > > range[0] = 40960; > > range[1] = 134217728; > > range[2] = 4096; > > > > fd = open(argv[1], O_RDONLY); > > if (fd < 0) { > > perror("open"); > > return 1; > > } > > > > if (ioctl(fd, FITRIM, range)) { > > if (errno == EOPNOTSUPP) > > fprintf(stderr, "FITRIM not supported\n"); > > else > > perror("FITRIM"); > > return 1; > > } > > > > return 0; > > } > > > > Range items have following meaning: > > > > range[0] - (start) first Byte to trim > > range[1] - (len) number of Bytes to trim from start > > range[2] - (minlen) minimum extent length to trim, free extents shorter > > than this number of Bytes will be ignored. This number will be rounded > > up to the block size. > > > > So in my example it will trim all free extents from block 10 of first > > alloc. group to block 10 of second alloc. group, assuming we have > > block_size = 4096. > > > > Also, when you want to trim the whole fs, you can simply pass NULL > > instead of range into the ioctl, or you can specify the range correctly > > to cover the whole fs. > > > > Regards > > -Lukas > > > > [PATCH 1/3] Add ioctl FITRIM. > > [PATCH 2/3] Add batched discard support for ext3 > > [PATCH 3/3] Add batched discard support for ext4 > > > > fs/ext3/balloc.c | 249 +++++++++++++++++++++++++++++++++++++++++++++++ > > fs/ext3/super.c | 1 + > > fs/ext4/ext4.h | 2 + > > fs/ext4/mballoc.c | 194 ++++++++++++++++++++++++++++++++++++ > > fs/ext4/super.c | 1 + > > fs/ioctl.c | 34 +++++++ > > include/linux/ext3_fs.h | 1 + > > include/linux/fs.h | 2 + > > 8 files changed, 484 insertions(+), 0 deletions(-) > -- -- 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
