diff options
| -rw-r--r-- | sys/ufs/ufs/ufs_readwrite.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/sys/ufs/ufs/ufs_readwrite.c b/sys/ufs/ufs/ufs_readwrite.c index af7298c..c76081f 100644 --- a/sys/ufs/ufs/ufs_readwrite.c +++ b/sys/ufs/ufs/ufs_readwrite.c @@ -491,23 +491,27 @@ WRITE(ap) vnode_pager_setsize(vp, uio->uio_offset + xfersize); /* - * Avoid a data-consistency race between write() and mmap() - * by ensuring that newly allocated blocks are zerod. The - * race can occur even in the case where the write covers - * the entire block. + * We must perform a read-before-write if the transfer size + * does not cover the entire buffer. */ - flags |= B_CLRBUF; -#if 0 if (fs->fs_bsize > xfersize) flags |= B_CLRBUF; else flags &= ~B_CLRBUF; -#endif /* XXX is uio->uio_offset the right thing here? */ error = UFS_BALLOC(vp, uio->uio_offset, xfersize, ap->a_cred, flags, &bp); if (error != 0) break; + /* + * If the buffer is not valid we have to clear out any + * garbage data from the pages instantiated for the buffer. + * If we do not, a failed uiomove() during a write can leave + * the prior contents of the pages exposed to a userland + * mmap(). XXX deal with uiomove() errors a better way. + */ + if ((bp->b_flags & B_CACHE) == 0 && fs->fs_bsize <= xfersize) + vfs_bio_clrbuf(bp); if (ioflag & IO_DIRECT) bp->b_flags |= B_DIRECT; if (ioflag & IO_NOWDRAIN) |
