Date: Wed, 17 Jul 2019 17:01:07 +0000 (UTC) From: Alan Somers <asomers@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r350088 - head/sys/kern Message-ID: <201907171701.x6HH17p9006383@repo.freebsd.org>
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Author: asomers Date: Wed Jul 17 17:01:07 2019 New Revision: 350088 URL: https://svnweb.freebsd.org/changeset/base/350088 Log: F_READAHEAD: Fix r349248's overflow protection, broken by r349391 I accidentally broke the main point of r349248 when making stylistic changes in r349391. Restore the original behavior, and also fix an additional overflow that was possible when uio->uio_resid was nearly SSIZE_MAX. Reported by: cem Reviewed by: bde MFC after: 2 weeks MFC-With: 349248 Sponsored by: The FreeBSD Foundation Modified: head/sys/kern/vfs_vnops.c Modified: head/sys/kern/vfs_vnops.c ============================================================================== --- head/sys/kern/vfs_vnops.c Wed Jul 17 16:52:25 2019 (r350087) +++ head/sys/kern/vfs_vnops.c Wed Jul 17 17:01:07 2019 (r350088) @@ -499,8 +499,13 @@ sequential_heuristic(struct uio *uio, struct file *fp) * closely related to the best I/O size for real disks than * to any block size used by software. */ - fp->f_seqcount += lmin(IO_SEQMAX, - howmany(uio->uio_resid, 16384)); + if (uio->uio_resid >= IO_SEQMAX * 16384) + fp->f_seqcount = IO_SEQMAX; + else { + fp->f_seqcount += howmany(uio->uio_resid, 16384); + if (fp->f_seqcount > IO_SEQMAX) + fp->f_seqcount = IO_SEQMAX; + } return (fp->f_seqcount << IO_SEQSHIFT); }
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