From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q4ML5IBx255128 for ; Tue, 22 May 2012 16:05:18 -0500 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id kkkOpwE8yDB2o7sv for ; Mon, 21 May 2012 15:10:52 -0700 (PDT) Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q4LMAp3L032041 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 21 May 2012 18:10:51 -0400 Message-ID: <4FBABD6A.6070800@redhat.com> Date: Mon, 21 May 2012 17:10:50 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: [PATCH 2/3] xfs_repair: Document & robustify blkmap_next_off() References: <4FBABCAB.20300@redhat.com> In-Reply-To: <4FBABCAB.20300@redhat.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: xfs-oss blkmap_next_off() was cryptic (to me), so document what it does. Also catch cases when the passed in extent index 't' is beyond the number of extents in the blkmap, so that: ext = blkmap->exts + *t; doesn't walk off the end of the array into garbage. Signed-off-by: Eric Sandeen --- diff --git a/repair/bmap.c b/repair/bmap.c index c43ca7f..85d66dc 100644 --- a/repair/bmap.c +++ b/repair/bmap.c @@ -206,8 +206,25 @@ blkmap_last_off( return ext->startoff + ext->blockcount; } -/* - * Return the next offset in a block map. +/** + * blkmap_next_off - Return next logical block offset in a block map. + * @blkmap: blockmap to use + * @o: current file logical block number + * @t: current extent index into blockmap (in/out) + * + * Given a logical block offset in a file, return the next mapped logical offset + * The map index "t" tracks the current extent number in the block map, and + * is updated automatically if the returned offset resides within the next + * mapped extent. + * + * If the blockmap contains no extents, or no more logical offsets are mapped, + * or the extent index exceeds the number of extents in the map, + * return NULLDFILOFF. + * + * If offset o is beyond extent index t, the first offset in the next extent + * after extent t will be returned. + * + * Intended to be called starting with offset 0, index 0, and iterated. */ xfs_dfiloff_t blkmap_next_off( @@ -223,10 +240,12 @@ blkmap_next_off( *t = 0; return blkmap->exts[0].startoff; } + if (*t >= blkmap->nexts) + return NULLDFILOFF; ext = blkmap->exts + *t; if (o < ext->startoff + ext->blockcount - 1) return o + 1; - if (*t >= blkmap->nexts - 1) + if (*t == blkmap->nexts - 1) return NULLDFILOFF; (*t)++; return ext[1].startoff; _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs