Hello all, hope I am right here. We have some questions concerning the ext2 filesystem: When looking for free blocks and inodes in function ext2_statfs the overhead, free inodes and free blocks are newly calculated by iterating through all inodes and blocks and look if they are free or not. On the other hand free inodes and free blocks are held in the structure-members s_freeinode_count and s_free_block_count of the superblock info. Now my questions: Why is the overhead calculated ? Isn't it is constant since filling the superblock ? Wy are free blocks and free inodes are calculated every time, when they are held in s_freeinode_count and s_free_block_count ? Isn't it is possible to use these variables directly ? By the way: s_freeinode_count is not incremented in function ext2_release_inode. The background for these questions is as it always is: We have a problem using 320 GB harddrives instead of 80 GB harddrives with ext2. Before writing to the harddrive our software looks for enough space to make sure the data can be stored safely. This leads to heavy performance problems when using larger disks. We can reduce the check for enough space to every 10th or 100th write operation, but at some point our software has to check and this may lead to a los of data because the system is busy calculating the free inodes and blocks. Our solution will be to create a patch using the structure members s_freeinode_count, s_free_block_count and create a new member s_overhead_count and use them directly. s_overhead_count is calculated once when filling the superblock. Is this a good solution or are there circumstances which can lead to a misbehavior ? Thanks in advance, Björn Slotkowski -- imc Messsysteme GmbH Bereich Entwicklung / Dept. Development Voltastraße 5 D-13355 Berlin Germany Tel: +49 30 46 70 90 23 Fax: +49 30 46 31 57 6 mailto:Bjoern.Slotkowski@xxxxxxxxxxxxx Homepage: http://www.imc-berlin.de Sitz der Gesellschaft : Berlin Handelsregister : Berlin-Charlottenburg HRB 28778 Geschäftsführer : Dr.-Ing. Dietmar Sprenger -- 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
