On Sun, Dec 12, 2010 at 07:37:54PM -0000, Kazuya Mio wrote: > Hi, > > ext4_ext_find_goal() returns an ideal physical block number that the block > allocator tries to allocate first. However, if a required file offset is > smaller than the existing extent's one, ext4_ext_find_goal() returns > a wrong block number because it may overflow at > "block - le32_to_cpu(ex->ee_block)". This patch fixes the problem. Thanks, applied. One comment which I've added to the code: The block placement algorithm in this section of code assumes that we are filling in a file which will eventually be non-sparse --- i.e., in the case of libbfd writing an ELF object sections out-of-order but in a way the eventually results in a contiguous object or executable file, or the old BSD dbm library writing dbm files. However, this is actually somewhat non-ideal if we are writing a sparse file such as qemu or KVM writing a raw image file, as it will result in the free space getting unnecessarily fragmented. Maybe we should have some hueristics to determine whether we are in the first or second case? I don't currently think using raw image files is that common in most virtualization application, but if someone can think of some common use cases where we would care, it might be worth adding either some hueristics to detect this, or perhaps some way that userspace can pass a hint to the file system that what we're doing is writing a raw sparse file. For now I'm going to consider the first scenario more common than the second.... - 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
