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Re: [Cluster-devel] [GFS2 PATCH] GFS2: Set log descriptor type for jdata blocks



----- Original Message -----
| Hi,
| 
| On Fri, 2013-05-24 at 15:02 -0400, Bob Peterson wrote:
| > Hi,
| > 
| > This patch sets the log descriptor type according to whether the
| > journal commit is for (journaled) data or metadata. This was
| > recently broken when the functions to process data and metadata
| > log ops were combined.
| > 
| > Regards,
| > 
| > Bob Peterson
| > Red Hat File Systems
| > 
| Thanks - looks good. If we can automatically detect the erroneous
| entries, could we also automatically deal with those too? That might be
| useful in case people already have such entries in their logs,
| 
| Steve.

Hi,

Don't consider this a patch submission quite yet, but:
I wrote the following patch to do what you're suggesting. It detects the
bad blocks in the journal and adjusts accordingly. I've tested this with
both sets of corrupt metadata I have in my possession, and instrumentation
shows that it works properly.

Is this the kind of thing you had in mind? Is there a better way
to do this? Or do you have any suggestions for improvements?

Regards,

Bob Peterson
---
 fs/gfs2/lops.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 33f18b7..5a34e7e 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -31,6 +31,10 @@
 #include "util.h"
 #include "trace_gfs2.h"
 
+static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
+				    struct gfs2_log_descriptor *ld,
+				    __be64 *ptr, int pass);
+
 /**
  * gfs2_pin - Pin a buffer in memory
  * @sdp: The superblock
@@ -530,6 +534,23 @@ static void buf_lo_before_scan(struct gfs2_jdesc *jd,
 	sdp->sd_replayed_blocks = 0;
 }
 
+static bool is_mismarked_databuf(struct gfs2_sbd *sdp, __be64 *ptr,
+				 unsigned int blks)
+{
+	u64 sb_addr = GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift;
+
+	while (blks) {
+		if (be64_to_cpu(*ptr) <= sb_addr)
+			return false;
+		ptr++;
+		if (be64_to_cpu(*ptr) > 1)
+			return false;
+		ptr++;
+		blks--;
+	}
+	return true;
+}
+
 static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 				struct gfs2_log_descriptor *ld, __be64 *ptr,
 				int pass)
@@ -545,6 +566,9 @@ static int buf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
 	if (pass != 1 || be32_to_cpu(ld->ld_type) != GFS2_LOG_DESC_METADATA)
 		return 0;
 
+	if (is_mismarked_databuf(sdp, ptr, blks))
+		return databuf_lo_scan_elements(jd, start, ld, ptr, pass);
+	
 	gfs2_replay_incr_blk(sdp, &start);
 
 	for (; blks; gfs2_replay_incr_blk(sdp, &start), blks--) {


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