On Sun, Apr 08, 2007 at 02:39:03PM +0800, coly wrote: > Hi, list: > > I find size of struct ext4_inode is 152 bytes, but from the dumpe2fs, it > tells me the inode size is 128 bytes. > > I am confused that, the ext4_inode is the on-disk inode format, so how > can dumpe2fs tells the inode size is 128 bytes. > > Further more, when I use sb_bread() to read inode from inode table (with > 152 bytes inode size), I can not read proper data from the bh->b_data. > Once I use 128 bytes inode size, I can read what I want from the > bh->b_data. The inode size for ext4 filesystems can be multiple sizes; the traditional ext2/ext3 inode size is 128 bytes. If so, then you won't have any of the features that require inode fields starting at i_extra_isize. If you use an inode size of 256 bytes, then you will be able to use nanosecond granularity timestamps, and the extra space (256-152 bytes) can be used for fast access to extended attributes. If there is an expectation that the filesystem will need a larger amount of space for extended attributes, the filesystem can be formatted with 512, 1024, or even larger sizes (so long as it is a power of two >= 128 bytes). - 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
