Date: Sun, 13 Feb 2011 21:51:31 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Konstantin Belousov <kib@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r218603 - head/sbin/tunefs Message-ID: <20110213213251.B1474@besplex.bde.org> In-Reply-To: <201102121312.p1CDCjhD002584@svn.freebsd.org> References: <201102121312.p1CDCjhD002584@svn.freebsd.org>
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On Sat, 12 Feb 2011, Konstantin Belousov wrote: > Log: > When creating a directory entry for the journal, always read at least > the fragment, and write the full block. Reading less might not work > due to device sector size bigger then size of direntries in the > last directory fragment. I think it should always write full fragments too (and the kernel should always read/write in units of fragments, not sectors of any size). > Modified: head/sbin/tunefs/tunefs.c > ============================================================================== > --- head/sbin/tunefs/tunefs.c Sat Feb 12 12:52:12 2011 (r218602) > +++ head/sbin/tunefs/tunefs.c Sat Feb 12 13:12:45 2011 (r218603) > @@ -733,16 +740,19 @@ dir_extend(ufs2_daddr_t blk, ufs2_daddr_ > { > char block[MAXBSIZE]; > > - if (bread(&disk, fsbtodb(&sblock, blk), block, size) <= 0) { > + if (bread(&disk, fsbtodb(&sblock, blk), block, > + roundup(size, sblock.fs_fsize)) <= 0) { Rounding up to a fragment boundary is spelled fragroundup(fs, size) in ffs. This use fs->fs_qfmask and fs->fs_fmask for optimality. It is unclear if the kernel macros work in userland, but here we already use fsbtodb() which uses fs->fsbtodb for optimality. [I've just learned again about fragroundup() after trying to fix rounding in cluster_read(). See blksize(). Since cluster_read() doesn't know about the fragment size or the fs dependencies in blksize(), it cannot read ahead correctly across i/o size boundaries (exactly one of which occurs near EOF for almost all files with fragments in ffs). This bug is missing in old breadn() -- it can even handle multiple i/o size boundaries, since it is passed a separate size for every block.] Bruce
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