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Date: Tue, 16 Jan 2007 12:21:34 -0700 From: Andreas Dilger <adilger@...sterfs.com> To: sho@...s.nec.co.jp Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: Re: [RFC][PATCH 0/3] ext4 online defrag (ver 0.2) On Jan 16, 2007 21:03 +0900, sho@...s.nec.co.jp wrote: > 1. Add new ioctl(EXT4_IOC_DEFRAG) which returns the first physical > block number of the specified file. With this ioctl, a command > gets the specified directory's. Maybe I don't understand, but how is this different from the long-time FIBMAP ioctl? > 2. The new entry "goal" is added on ext4_ext_defrag_data structure > which is passed to existing ioctl(EXT4_IOC_DEFRAG) > as the argument. The kernel starts searching the free blocks > from "goal". The command passes the physical block number > gotten in the above step(1) to the ioctl. > > struct ext4_ext_defrag_data { > loff_t start_offset; /* start offset to defrag in byte */ > loff_t defrag_size; /* size of defrag in bytes */ > ext4_fsblk_t goal; /* block offset for allocation */ > }; Two things of note: - presumably the start_offset and defrag_size should be multiples of the filesystem blocksize? If they are not, is it an error or are they adjusted to cover whole blocks? - in previous defrag discussions (i.e. XFS defrag), it was desirable to allow specifying different types of goals (e.g. hard, soft, kernel picks). We may as well have a structure that allows these to be specified, instead of having to change the interface afterward. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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