On Thu, Apr 30, 2015 at 07:12:04PM +0900, Chanho Park wrote: > > In my situation, I usually use the "resize2fs -M" when making a tizen > platform image. As you know, like android, tizen also uses ext4 filesystem > and flash the image from bootloader. Instead of flashing full image size, we > only flash shrinked filesystem image to reduce flashing time and want to > avoid download huge files. If the partition size is 3GB, we'll make a 3GB > loop image and fill files into it. And I shrink the loop image to the > minimum size and flash it to my phone. When first booting, the system will > do resizing the partition to 3GB original size. What I would recommend is to estimate how big the file system needs to doing a "du -s" over the directory that you want to preload onto the file system size, add say, 5% or so the file system metadata, and then create the file system that way. If the file system is close enough to the right size, then resize2fs -M is much more likely to shrink the file system to its minimal size, and also reduce the file fragmentation that results from it. (One of the better uses for using resize2fs to slightly shrink a file system was to make room for the LVM table at the end of the device, for example. It's when you try to take, say, a 1TB file system and shrink to a few megabytes that resize2fs doesn't do a great job, because it really wasn't engineered for that use case, and it's hard enough to make sure it does so in a efficient and robust manner as it is.) You can then take that file system and shrink to a size far larger than what it was originally created as --- that works much better than taking a large empty file system, shrinking it down to its minimal size, and then expanding it to something bigger. If necessary, you can use the "mke2fs -E resize=15T" option to make sure enough metadata blocks have been reserved so the file system can be expanded as much as you would like. By default we reserve enough metadata blocks for the file system to grow by a factor of a thousand, so if you create a super-tiny file system and then expect to grow it to a multi-TB size, that mke2fs option will be useful. It's not strictly necessary for ext4 (although it was required for ext3), but it will result in a slightly more efficient file system that will mount more quickly under ext4. So if your Tizen image is, say, 390 megabytes, I'd suggest creating a 400 megabyte file system, and load that up with the image. If you then use resize2fs -M, it should shirnk it down to something much closer to 390M. I suspect you will find that the resulting image will be far more efficient than trying to start with a 3GB file system, shrink it down to 400M, and then expand it backup to 3GB. Best regards, - Ted -- 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
