[PATCH 0/9] xfs_db, xfs_repair: improve CRC error detection

[PATCH 0/9] xfs_db, xfs_repair: improve CRC error detection

[Dave Chinner]

Hi folks,

After a conversion with a user on #IRC this morning, it was clear
that xfs_repair and xfs_db weren't handling metadata blocks with CRC
errors in them particularly well. xfs_metadump was reporting blocks
with errors, but xfs_db was reporting them as having a correct CRC,
which wasn't actually the case - they were unchecked, and the code
saw the absence of error flags as meaning they were good.

Repair had a similar problem - buffers that were prefetched never
had the verifier run on them when they were read by the checking
code as they were uptodate in the cache. Hence the prefetch code
needed to mark the buffers as unchecked so that the code that
checked the metadata ran the verifier and appropriately.

This then showed up the fact that there were many places where
repair was not catching the CRC error and rewriting the buffer to
correct the bad CRC.

This then showed up that we weren't actually handling remote
attribute properly for the CRC enabled format.

And so I fixed all of them. I've verified the code by manually
corrupting blocks with xfs_db by writing garabges into unused
regions of the blocks so that CRC errors are triggered. In each case
repair detected the CRC error and took appropriate action. The CRC
error was not found on a second run of xfs_repair. This really needs
to be turned into a xfstest, but I haven't had time to do that yet.
Any volunteers?

Anyway, these fixes mean we'll definitely need a 3.2.0-rc2 release
in the not too distant future. Comments, flames and testing all
welcome....

-Dave.

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[PATCH 1/9] db: don't claim unchecked CRCs are correct

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Currently xfs_db will claim the CRC on a structure is correct if the
buffer is not marked with an error. However, buffers may have been
read without a verifier, and hence have not had their CRCs
validated. in this case, we shoul dreport "unchecked" rather than
"correct". For example:

xfs_db> fsb 0x6003f
xfs_db> type dir3
xfs_db> p
dhdr.hdr.magic = 0x58444433
dhdr.hdr.crc = 0x2d0f9c9d (unchecked)
....

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 db/fprint.c | 15 ++++++++++++++-
 db/io.c     |  2 ++
 db/io.h     | 12 +++++++++---
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/db/fprint.c b/db/fprint.c
index 435d984..52782e2 100644
--- a/db/fprint.c
+++ b/db/fprint.c
@@ -206,7 +206,20 @@ fp_crc(
 	__int64_t	val;
 	char		*ok;
 
-	ok = iocur_crc_valid() ? "correct" : "bad";
+	switch (iocur_crc_valid()) {
+	case -1:
+		ok = "unchecked";
+		break;
+	case 0:
+		ok = "bad";
+		break;
+	case 1:
+		ok = "correct";
+		break;
+	default:
+		ok = "unknown state";
+		break;
+	}
 
 	for (i = 0, bitpos = bit;
 	     i < count && !seenint();
diff --git a/db/io.c b/db/io.c
index 5eb61d9..387f171 100644
--- a/db/io.c
+++ b/db/io.c
@@ -531,6 +531,8 @@ set_cur(
 		return;
 	iocur_top->buf = bp->b_addr;
 	iocur_top->bp = bp;
+	if (!ops)
+		bp->b_flags |= LIBXFS_B_UNCHECKED;
 
 	iocur_top->bb = d;
 	iocur_top->blen = c;
diff --git a/db/io.h b/db/io.h
index ad39bee..7875119 100644
--- a/db/io.h
+++ b/db/io.h
@@ -63,10 +63,16 @@ extern void	set_cur(const struct typ *t, __int64_t d, int c, int ring_add,
 			bbmap_t *bbmap);
 extern void     ring_add(void);
 
-static inline bool
+/*
+ * returns -1 for unchecked, 0 for bad and 1 for good
+ */
+static inline int
 iocur_crc_valid()
 {
-	return (iocur_top->bp &&
-		iocur_top->bp->b_error != EFSBADCRC &&
+	if (!iocur_top->bp)
+		return -1;
+	if (iocur_top->bp->b_flags & LIBXFS_B_UNCHECKED)
+		return -1;
+	return (iocur_top->bp->b_error != EFSBADCRC &&
 		(!iocur_top->ino_buf || iocur_top->ino_crc_ok));
 }
-- 
1.9.0

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Re: [PATCH 1/9] db: don't claim unchecked CRCs are correct

[Christoph Hellwig]

> +	switch (iocur_crc_valid()) {
> +	case -1:
> +		ok = "unchecked";
> +		break;
> +	case 0:
> +		ok = "bad";
> +		break;
> +	case 1:
> +		ok = "correct";
> +		break;
> +	default:
> +		ok = "unknown state";
> +		break;
> +	}

We should have symbolic constants for these return values.  But then
again iocur_crc_valid only has a single caller currently, is it even
worth the effort, or should we simply inline it?

Otherwise looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

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Re: [PATCH 1/9] db: don't claim unchecked CRCs are correct

[Dave Chinner]

On Mon, Apr 21, 2014 at 12:00:09AM -0700, Christoph Hellwig wrote:
> > +	switch (iocur_crc_valid()) {
> > +	case -1:
> > +		ok = "unchecked";
> > +		break;
> > +	case 0:
> > +		ok = "bad";
> > +		break;
> > +	case 1:
> > +		ok = "correct";
> > +		break;
> > +	default:
> > +		ok = "unknown state";
> > +		break;
> > +	}
> 
> We should have symbolic constants for these return values.  But then
> again iocur_crc_valid only has a single caller currently, is it even
> worth the effort, or should we simply inline it?

If we grow another user, I'll add an enum for it...

> Otherwise looks good,
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Thanks.

-- 
Dave Chinner
david@fromorbit.com

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[PATCH 2/9] db: verify buffer on type change

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Currently when the type command is run, we simply change the type
associated with the buffer, but don't verify it. This results in
unchecked CRCs being displayed. Hence when changing the type, run
the verifier associated with the type to determine if the buffer
contents is valid or not.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 db/io.c   | 25 +++++++++++++++++++++++++
 db/io.h   |  1 +
 db/type.c |  9 +++++----
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/db/io.c b/db/io.c
index 387f171..1a75394 100644
--- a/db/io.c
+++ b/db/io.c
@@ -552,6 +552,31 @@ set_cur(
 		ring_add();
 }
 
+void
+set_iocur_type(
+	const typ_t	*t)
+{
+	const struct xfs_buf_ops *ops = t ? t->bops : NULL;
+	struct xfs_buf	*bp = iocur_top->bp;
+
+	iocur_top->typ = t;
+
+	/* verify the buffer if the type has one. */
+	if (!bp)
+		return;
+	if (!ops) {
+		bp->b_ops = NULL;
+		bp->b_flags |= LIBXFS_B_UNCHECKED;
+		return;
+	}
+	if (!(bp->b_flags & LIBXFS_B_UPTODATE))
+		return;
+	bp->b_error = 0;
+	bp->b_ops = ops;
+	bp->b_ops->verify_read(bp);
+	bp->b_flags &= ~LIBXFS_B_UNCHECKED;
+}
+
 static void
 stack_help(void)
 {
diff --git a/db/io.h b/db/io.h
index 7875119..71082e6 100644
--- a/db/io.h
+++ b/db/io.h
@@ -62,6 +62,7 @@ extern void     write_cur(void);
 extern void	set_cur(const struct typ *t, __int64_t d, int c, int ring_add,
 			bbmap_t *bbmap);
 extern void     ring_add(void);
+extern void	set_iocur_type(const struct typ *t);
 
 /*
  * returns -1 for unchecked, 0 for bad and 1 for good
diff --git a/db/type.c b/db/type.c
index 04d0d56..b29f2a4 100644
--- a/db/type.c
+++ b/db/type.c
@@ -162,10 +162,11 @@ type_f(
 		if (tt == NULL) {
 			dbprintf(_("no such type %s\n"), argv[1]);
 		} else {
-			if (iocur_top->typ == NULL) {
-			    dbprintf(_("no current object\n"));
-			} else {
-			    iocur_top->typ = cur_typ = tt;
+			if (iocur_top->typ == NULL)
+				dbprintf(_("no current object\n"));
+			else {
+				cur_typ = tt;
+				set_iocur_type(tt);
 			}
 		}
 	}
-- 
1.9.0

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Re: [PATCH 2/9] db: verify buffer on type change

[Christoph Hellwig]

> +void
> +set_iocur_type(
> +	const typ_t	*t)
> +{
> +	const struct xfs_buf_ops *ops = t ? t->bops : NULL;
> +	struct xfs_buf	*bp = iocur_top->bp;
> +
> +	iocur_top->typ = t;
> +
> +	/* verify the buffer if the type has one. */
> +	if (!bp)
> +		return;
> +	if (!ops) {
> +		bp->b_ops = NULL;
> +		bp->b_flags |= LIBXFS_B_UNCHECKED;
> +		return;
> +	}

The only caller currently makes sure we never pass a NULL t argument,
and I think keeping it that way is sensible.  If we want to allow
clearing the type we should add a separate clear_iocur_type helper for
it.

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Re: [PATCH 2/9] db: verify buffer on type change

[Dave Chinner]

On Mon, Apr 21, 2014 at 12:02:52AM -0700, Christoph Hellwig wrote:
> > +void
> > +set_iocur_type(
> > +	const typ_t	*t)
> > +{
> > +	const struct xfs_buf_ops *ops = t ? t->bops : NULL;
> > +	struct xfs_buf	*bp = iocur_top->bp;
> > +
> > +	iocur_top->typ = t;
> > +
> > +	/* verify the buffer if the type has one. */
> > +	if (!bp)
> > +		return;
> > +	if (!ops) {
> > +		bp->b_ops = NULL;
> > +		bp->b_flags |= LIBXFS_B_UNCHECKED;
> > +		return;
> > +	}
> 
> The only caller currently makes sure we never pass a NULL t argument,
> and I think keeping it that way is sensible.  If we want to allow
> clearing the type we should add a separate clear_iocur_type helper for
> it.

Ok, I'll clear the conditional initialisation of *ops.

-- 
Dave Chinner
david@fromorbit.com

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[PATCH 3/9] repair: ensure prefetched buffers have CRCs validated

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Prefetch currently does not do CRC validation when the IO completes
due to the optimisation it performs and the fact that it does not
know what the type of metadata into the buffer is supposed to be.
Hence, mark all prefetched buffers as "suspect" so that when the
end user tries to read it with a supplied validation function the
validation is run even though the buffer was already in the cache.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 include/libxfs.h  |  1 +
 libxfs/rdwr.c     | 36 +++++++++++++++++++++++++++++++-----
 repair/prefetch.c |  3 +++
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/include/libxfs.h b/include/libxfs.h
index 6bc6c94..6b1e276 100644
--- a/include/libxfs.h
+++ b/include/libxfs.h
@@ -333,6 +333,7 @@ enum xfs_buf_flags_t {	/* b_flags bits */
 	LIBXFS_B_STALE		= 0x0004,	/* buffer marked as invalid */
 	LIBXFS_B_UPTODATE	= 0x0008,	/* buffer is sync'd to disk */
 	LIBXFS_B_DISCONTIG	= 0x0010,	/* discontiguous buffer */
+	LIBXFS_B_UNCHECKED	= 0x0020,	/* needs verification */
 };
 
 #define XFS_BUF_DADDR_NULL		((xfs_daddr_t) (-1LL))
diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index 7208a2f..a8f06aa 100644
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -718,12 +718,25 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
 	bp = libxfs_getbuf(btp, blkno, len);
 	if (!bp)
 		return NULL;
-	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY)))
+
+	/*
+	 * if the buffer was prefetched, it is likely that it was not
+	 * validated. Hence if we are supplied an ops function and the
+	 * buffer is marked as unchecked, we need to validate it now.
+	 */
+	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
+		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
+			bp->b_error = 0;
+			bp->b_ops = ops;
+			bp->b_ops->verify_read(bp);
+			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
+		}
 		return bp;
+	}
 
 	/*
-	 * only set the ops on a cache miss (i.e. first physical read) as the
-	 * verifier may change the ops to match the typ eof buffer it contains.
+	 * Set the ops on a cache miss (i.e. first physical read) as the
+	 * verifier may change the ops to match the type of buffer it contains.
 	 * A cache hit might reset the verifier to the original type if we set
 	 * it again, but it won't get called again and set to match the buffer
 	 * contents. *cough* xfs_da_node_buf_ops *cough*.
@@ -733,8 +746,10 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
 	error = libxfs_readbufr(btp, blkno, bp, len, flags);
 	if (error)
 		bp->b_error = error;
-	else if (bp->b_ops)
+	else if (bp->b_ops) {
 		bp->b_ops->verify_read(bp);
+		bp->b_flags &= ~LIBXFS_B_UNCHECKED;
+	}
 	return bp;
 }
 
@@ -786,6 +801,14 @@ libxfs_readbuf_map(struct xfs_buftarg *btp, struct xfs_buf_map *map, int nmaps,
 		return NULL;
 
 	bp->b_error = 0;
+	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
+		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
+			bp->b_ops = ops;
+			bp->b_ops->verify_read(bp);
+			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
+		}
+		return bp;
+	}
 	bp->b_ops = ops;
 	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY)))
 		return bp;
@@ -793,8 +816,10 @@ libxfs_readbuf_map(struct xfs_buftarg *btp, struct xfs_buf_map *map, int nmaps,
 	error = libxfs_readbufr_map(btp, bp, flags);
 	if (!error) {
 		bp->b_flags |= LIBXFS_B_UPTODATE;
-		if (bp->b_ops)
+		if (bp->b_ops) {
 			bp->b_ops->verify_read(bp);
+			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
+		}
 	}
 #ifdef IO_DEBUG
 	printf("%lx: %s: read %lu bytes, error %d, blkno=%llu(%llu), %p\n",
@@ -889,6 +914,7 @@ libxfs_writebufr(xfs_buf_t *bp)
 	if (!error) {
 		bp->b_flags |= LIBXFS_B_UPTODATE;
 		bp->b_flags &= ~(LIBXFS_B_DIRTY | LIBXFS_B_EXIT);
+		bp->b_flags &= ~LIBXFS_B_UNCHECKED;
 	}
 	return error;
 }
diff --git a/repair/prefetch.c b/repair/prefetch.c
index 6d6d344..d794ba3 100644
--- a/repair/prefetch.c
+++ b/repair/prefetch.c
@@ -389,6 +389,7 @@ pf_read_inode_dirs(
 
 	bp->b_ops = &xfs_inode_buf_ops;
 	bp->b_ops->verify_read(bp);
+	bp->b_flags &= ~LIBXFS_B_UNCHECKED;
 	if (bp->b_error)
 		return;
 
@@ -460,6 +461,7 @@ pf_read_discontig(
 
 	pthread_mutex_unlock(&args->lock);
 	libxfs_readbufr_map(mp->m_ddev_targp, bp, 0);
+	bp->b_flags |= LIBXFS_B_UNCHECKED;
 	libxfs_putbuf(bp);
 	pthread_mutex_lock(&args->lock);
 }
@@ -583,6 +585,7 @@ pf_batch_read(
 					break;
 				memcpy(XFS_BUF_PTR(bplist[i]), pbuf, size);
 				bplist[i]->b_flags |= LIBXFS_B_UPTODATE;
+				bplist[i]->b_flags |= LIBXFS_B_UNCHECKED;
 				len -= size;
 				if (B_IS_INODE(XFS_BUF_PRIORITY(bplist[i])))
 					pf_read_inode_dirs(args, bplist[i]);
-- 
1.9.0

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Re: [PATCH 3/9] repair: ensure prefetched buffers have CRCs validated

[Brian Foster]

On Tue, Apr 15, 2014 at 06:24:55PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> Prefetch currently does not do CRC validation when the IO completes
> due to the optimisation it performs and the fact that it does not
> know what the type of metadata into the buffer is supposed to be.
> Hence, mark all prefetched buffers as "suspect" so that when the
> end user tries to read it with a supplied validation function the
> validation is run even though the buffer was already in the cache.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  include/libxfs.h  |  1 +
>  libxfs/rdwr.c     | 36 +++++++++++++++++++++++++++++++-----
>  repair/prefetch.c |  3 +++
>  3 files changed, 35 insertions(+), 5 deletions(-)
> 
> diff --git a/include/libxfs.h b/include/libxfs.h
> index 6bc6c94..6b1e276 100644
> --- a/include/libxfs.h
> +++ b/include/libxfs.h
> @@ -333,6 +333,7 @@ enum xfs_buf_flags_t {	/* b_flags bits */
>  	LIBXFS_B_STALE		= 0x0004,	/* buffer marked as invalid */
>  	LIBXFS_B_UPTODATE	= 0x0008,	/* buffer is sync'd to disk */
>  	LIBXFS_B_DISCONTIG	= 0x0010,	/* discontiguous buffer */
> +	LIBXFS_B_UNCHECKED	= 0x0020,	/* needs verification */

This is used in the first couple patches, so it should probably be
defined earlier (or shuffle those patches appropriately).

>  };
>  
>  #define XFS_BUF_DADDR_NULL		((xfs_daddr_t) (-1LL))
> diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
> index 7208a2f..a8f06aa 100644
> --- a/libxfs/rdwr.c
> +++ b/libxfs/rdwr.c
> @@ -718,12 +718,25 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
>  	bp = libxfs_getbuf(btp, blkno, len);
>  	if (!bp)
>  		return NULL;
> -	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY)))
> +
> +	/*
> +	 * if the buffer was prefetched, it is likely that it was not
> +	 * validated. Hence if we are supplied an ops function and the
> +	 * buffer is marked as unchecked, we need to validate it now.
> +	 */
> +	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
> +		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
> +			bp->b_error = 0;
> +			bp->b_ops = ops;
> +			bp->b_ops->verify_read(bp);
> +			bp->b_flags &= ~LIBXFS_B_UNCHECKED;

Should we always expect an unchecked buffer to be read with an ops
vector before being written? Even if so, this might look cleaner if we
didn't encode the possibility of running a read verifier on a dirty
buffer. I presume that would always fail as the crc is updated in the
write verifier.

> +		}
>  		return bp;
> +	}
>  
>  	/*
> -	 * only set the ops on a cache miss (i.e. first physical read) as the
> -	 * verifier may change the ops to match the typ eof buffer it contains.
> +	 * Set the ops on a cache miss (i.e. first physical read) as the
> +	 * verifier may change the ops to match the type of buffer it contains.
>  	 * A cache hit might reset the verifier to the original type if we set
>  	 * it again, but it won't get called again and set to match the buffer
>  	 * contents. *cough* xfs_da_node_buf_ops *cough*.
> @@ -733,8 +746,10 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
>  	error = libxfs_readbufr(btp, blkno, bp, len, flags);
>  	if (error)
>  		bp->b_error = error;
> -	else if (bp->b_ops)
> +	else if (bp->b_ops) {
>  		bp->b_ops->verify_read(bp);
> +		bp->b_flags &= ~LIBXFS_B_UNCHECKED;
> +	}
>  	return bp;
>  }
>  
> @@ -786,6 +801,14 @@ libxfs_readbuf_map(struct xfs_buftarg *btp, struct xfs_buf_map *map, int nmaps,
>  		return NULL;
>  
>  	bp->b_error = 0;
> +	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
> +		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
> +			bp->b_ops = ops;
> +			bp->b_ops->verify_read(bp);
> +			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
> +		}

Same comment here.

Brian

> +		return bp;
> +	}
>  	bp->b_ops = ops;
>  	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY)))
>  		return bp;
> @@ -793,8 +816,10 @@ libxfs_readbuf_map(struct xfs_buftarg *btp, struct xfs_buf_map *map, int nmaps,
>  	error = libxfs_readbufr_map(btp, bp, flags);
>  	if (!error) {
>  		bp->b_flags |= LIBXFS_B_UPTODATE;
> -		if (bp->b_ops)
> +		if (bp->b_ops) {
>  			bp->b_ops->verify_read(bp);
> +			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
> +		}
>  	}
>  #ifdef IO_DEBUG
>  	printf("%lx: %s: read %lu bytes, error %d, blkno=%llu(%llu), %p\n",
> @@ -889,6 +914,7 @@ libxfs_writebufr(xfs_buf_t *bp)
>  	if (!error) {
>  		bp->b_flags |= LIBXFS_B_UPTODATE;
>  		bp->b_flags &= ~(LIBXFS_B_DIRTY | LIBXFS_B_EXIT);
> +		bp->b_flags &= ~LIBXFS_B_UNCHECKED;
>  	}
>  	return error;
>  }
> diff --git a/repair/prefetch.c b/repair/prefetch.c
> index 6d6d344..d794ba3 100644
> --- a/repair/prefetch.c
> +++ b/repair/prefetch.c
> @@ -389,6 +389,7 @@ pf_read_inode_dirs(
>  
>  	bp->b_ops = &xfs_inode_buf_ops;
>  	bp->b_ops->verify_read(bp);
> +	bp->b_flags &= ~LIBXFS_B_UNCHECKED;
>  	if (bp->b_error)
>  		return;
>  
> @@ -460,6 +461,7 @@ pf_read_discontig(
>  
>  	pthread_mutex_unlock(&args->lock);
>  	libxfs_readbufr_map(mp->m_ddev_targp, bp, 0);
> +	bp->b_flags |= LIBXFS_B_UNCHECKED;
>  	libxfs_putbuf(bp);
>  	pthread_mutex_lock(&args->lock);
>  }
> @@ -583,6 +585,7 @@ pf_batch_read(
>  					break;
>  				memcpy(XFS_BUF_PTR(bplist[i]), pbuf, size);
>  				bplist[i]->b_flags |= LIBXFS_B_UPTODATE;
> +				bplist[i]->b_flags |= LIBXFS_B_UNCHECKED;
>  				len -= size;
>  				if (B_IS_INODE(XFS_BUF_PRIORITY(bplist[i])))
>  					pf_read_inode_dirs(args, bplist[i]);
> -- 
> 1.9.0
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 3/9] repair: ensure prefetched buffers have CRCs validated

[Dave Chinner]

On Tue, Apr 15, 2014 at 03:40:00PM -0400, Brian Foster wrote:
> On Tue, Apr 15, 2014 at 06:24:55PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > Prefetch currently does not do CRC validation when the IO completes
> > due to the optimisation it performs and the fact that it does not
> > know what the type of metadata into the buffer is supposed to be.
> > Hence, mark all prefetched buffers as "suspect" so that when the
> > end user tries to read it with a supplied validation function the
> > validation is run even though the buffer was already in the cache.
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  include/libxfs.h  |  1 +
> >  libxfs/rdwr.c     | 36 +++++++++++++++++++++++++++++++-----
> >  repair/prefetch.c |  3 +++
> >  3 files changed, 35 insertions(+), 5 deletions(-)
> > 
> > diff --git a/include/libxfs.h b/include/libxfs.h
> > index 6bc6c94..6b1e276 100644
> > --- a/include/libxfs.h
> > +++ b/include/libxfs.h
> > @@ -333,6 +333,7 @@ enum xfs_buf_flags_t {	/* b_flags bits */
> >  	LIBXFS_B_STALE		= 0x0004,	/* buffer marked as invalid */
> >  	LIBXFS_B_UPTODATE	= 0x0008,	/* buffer is sync'd to disk */
> >  	LIBXFS_B_DISCONTIG	= 0x0010,	/* discontiguous buffer */
> > +	LIBXFS_B_UNCHECKED	= 0x0020,	/* needs verification */
> 
> This is used in the first couple patches, so it should probably be
> defined earlier (or shuffle those patches appropriately).

Ah, I busted that on shuffling the patchset, and hadn't done a
patch-by-patch compile. Well spotted!

> 
> >  };
> >  
> >  #define XFS_BUF_DADDR_NULL		((xfs_daddr_t) (-1LL))
> > diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
> > index 7208a2f..a8f06aa 100644
> > --- a/libxfs/rdwr.c
> > +++ b/libxfs/rdwr.c
> > @@ -718,12 +718,25 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
> >  	bp = libxfs_getbuf(btp, blkno, len);
> >  	if (!bp)
> >  		return NULL;
> > -	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY)))
> > +
> > +	/*
> > +	 * if the buffer was prefetched, it is likely that it was not
> > +	 * validated. Hence if we are supplied an ops function and the
> > +	 * buffer is marked as unchecked, we need to validate it now.
> > +	 */
> > +	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
> > +		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
> > +			bp->b_error = 0;
> > +			bp->b_ops = ops;
> > +			bp->b_ops->verify_read(bp);
> > +			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
> 
> Should we always expect an unchecked buffer to be read with an ops
> vector before being written? Even if so, this might look cleaner if we
> didn't encode the possibility of running a read verifier on a dirty
> buffer. I presume that would always fail as the crc is updated in the
> write verifier.

It should fail, and that's a good thing because writing to an
unchecked buffer would indicate that we didn't validate it properly
in the first place. Hence I thought that doing it this way leaves
a canary that traps other problem usage with unchecked buffers.

Realistically, we shouldn't be writing unchecked buffers - prefetch
doesn't touch buffers, it just does IO, and so someone else has to
read the buffers before they can be dirtied. If it's read without an
ops structure then modified and read again with an ops structure,
we'll catch it...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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Re: [PATCH 3/9] repair: ensure prefetched buffers have CRCs validated

[Brian Foster]

On Wed, Apr 16, 2014 at 07:46:42AM +1000, Dave Chinner wrote:
> On Tue, Apr 15, 2014 at 03:40:00PM -0400, Brian Foster wrote:
> > On Tue, Apr 15, 2014 at 06:24:55PM +1000, Dave Chinner wrote:
> > > From: Dave Chinner <dchinner@redhat.com>
> > > 
> > > Prefetch currently does not do CRC validation when the IO completes
> > > due to the optimisation it performs and the fact that it does not
> > > know what the type of metadata into the buffer is supposed to be.
> > > Hence, mark all prefetched buffers as "suspect" so that when the
> > > end user tries to read it with a supplied validation function the
> > > validation is run even though the buffer was already in the cache.
> > > 
> > > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > > ---
> > >  include/libxfs.h  |  1 +
> > >  libxfs/rdwr.c     | 36 +++++++++++++++++++++++++++++++-----
> > >  repair/prefetch.c |  3 +++
> > >  3 files changed, 35 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/include/libxfs.h b/include/libxfs.h
> > > index 6bc6c94..6b1e276 100644
> > > --- a/include/libxfs.h
> > > +++ b/include/libxfs.h
> > > @@ -333,6 +333,7 @@ enum xfs_buf_flags_t {	/* b_flags bits */
> > >  	LIBXFS_B_STALE		= 0x0004,	/* buffer marked as invalid */
> > >  	LIBXFS_B_UPTODATE	= 0x0008,	/* buffer is sync'd to disk */
> > >  	LIBXFS_B_DISCONTIG	= 0x0010,	/* discontiguous buffer */
> > > +	LIBXFS_B_UNCHECKED	= 0x0020,	/* needs verification */
> > 
> > This is used in the first couple patches, so it should probably be
> > defined earlier (or shuffle those patches appropriately).
> 
> Ah, I busted that on shuffling the patchset, and hadn't done a
> patch-by-patch compile. Well spotted!
> 
> > 
> > >  };
> > >  
> > >  #define XFS_BUF_DADDR_NULL		((xfs_daddr_t) (-1LL))
> > > diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
> > > index 7208a2f..a8f06aa 100644
> > > --- a/libxfs/rdwr.c
> > > +++ b/libxfs/rdwr.c
> > > @@ -718,12 +718,25 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
> > >  	bp = libxfs_getbuf(btp, blkno, len);
> > >  	if (!bp)
> > >  		return NULL;
> > > -	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY)))
> > > +
> > > +	/*
> > > +	 * if the buffer was prefetched, it is likely that it was not
> > > +	 * validated. Hence if we are supplied an ops function and the
> > > +	 * buffer is marked as unchecked, we need to validate it now.
> > > +	 */
> > > +	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
> > > +		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
> > > +			bp->b_error = 0;
> > > +			bp->b_ops = ops;
> > > +			bp->b_ops->verify_read(bp);
> > > +			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
> > 
> > Should we always expect an unchecked buffer to be read with an ops
> > vector before being written? Even if so, this might look cleaner if we
> > didn't encode the possibility of running a read verifier on a dirty
> > buffer. I presume that would always fail as the crc is updated in the
> > write verifier.
> 
> It should fail, and that's a good thing because writing to an
> unchecked buffer would indicate that we didn't validate it properly
> in the first place. Hence I thought that doing it this way leaves
> a canary that traps other problem usage with unchecked buffers.
> 
> Realistically, we shouldn't be writing unchecked buffers - prefetch
> doesn't touch buffers, it just does IO, and so someone else has to
> read the buffers before they can be dirtied. If it's read without an
> ops structure then modified and read again with an ops structure,
> we'll catch it...
> 

Ah, I see. That sounds good, but a small comment there with the
reasoning to allow a read verifier to run on a dirty buffer would be
nice. :)

Brian

> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com

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Re: [PATCH 3/9] repair: ensure prefetched buffers have CRCs validated

[Dave Chinner]

On Tue, Apr 15, 2014 at 06:06:00PM -0400, Brian Foster wrote:
> On Wed, Apr 16, 2014 at 07:46:42AM +1000, Dave Chinner wrote:
> > On Tue, Apr 15, 2014 at 03:40:00PM -0400, Brian Foster wrote:
> > > Should we always expect an unchecked buffer to be read with an ops
> > > vector before being written? Even if so, this might look cleaner if we
> > > didn't encode the possibility of running a read verifier on a dirty
> > > buffer. I presume that would always fail as the crc is updated in the
> > > write verifier.
> > 
> > It should fail, and that's a good thing because writing to an
> > unchecked buffer would indicate that we didn't validate it properly
> > in the first place. Hence I thought that doing it this way leaves
> > a canary that traps other problem usage with unchecked buffers.
> > 
> > Realistically, we shouldn't be writing unchecked buffers - prefetch
> > doesn't touch buffers, it just does IO, and so someone else has to
> > read the buffers before they can be dirtied. If it's read without an
> > ops structure then modified and read again with an ops structure,
> > we'll catch it...
> > 
> 
> Ah, I see. That sounds good, but a small comment there with the
> reasoning to allow a read verifier to run on a dirty buffer would be
> nice. :)

Ok, I'll add one.

Cheers,

Dave.
-- 
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david@fromorbit.com

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[PATCH 4/9] repair: detect and correct CRC errors in directory blocks

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

repair doesn't currently verifier errors in directory blocks - they
cause repair to ignore blocks and hence fail because it can't read
critical blocks from the directory.

Fix this by having the directory buffer read code detect a verifier
error and retry the read without the verifier if the verifier has
detected an error. Then pass the verifer error with the successfully
read buffer back to the caller, so the caller can handle the error
appropriately. In most cases, this is simply marking the directory
as needing a rebuild, so once the directory entries have been
checked and repaired, it will rewrite all the directory buffers
(including the clean ones) and in the process recalculate all the
the CRC on the directory blocks.

Hence pure CRC errors in directory blocks are now handled correctly
by xfs_repair.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 libxfs/rdwr.c   |   3 +-
 repair/phase6.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 90 insertions(+), 21 deletions(-)

diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index a8f06aa..314c45d 100644
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -724,9 +724,9 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
 	 * validated. Hence if we are supplied an ops function and the
 	 * buffer is marked as unchecked, we need to validate it now.
 	 */
+	bp->b_error = 0;
 	if ((bp->b_flags & (LIBXFS_B_UPTODATE|LIBXFS_B_DIRTY))) {
 		if (ops && (bp->b_flags & LIBXFS_B_UNCHECKED)) {
-			bp->b_error = 0;
 			bp->b_ops = ops;
 			bp->b_ops->verify_read(bp);
 			bp->b_flags &= ~LIBXFS_B_UNCHECKED;
@@ -741,7 +741,6 @@ libxfs_readbuf(struct xfs_buftarg *btp, xfs_daddr_t blkno, int len, int flags,
 	 * it again, but it won't get called again and set to match the buffer
 	 * contents. *cough* xfs_da_node_buf_ops *cough*.
 	 */
-	bp->b_error = 0;
 	bp->b_ops = ops;
 	error = libxfs_readbufr(btp, blkno, bp, len, flags);
 	if (error)
diff --git a/repair/phase6.c b/repair/phase6.c
index 0c35e1c..6c5ff53 100644
--- a/repair/phase6.c
+++ b/repair/phase6.c
@@ -125,6 +125,43 @@ typedef struct freetab {
 #define	DIR_HASH_CK_TOTAL	6
 
 /*
+ * Need to handle CRC and validation errors specially here. If
+ * there is a validator error, re-read without the verifier so
+ * that we get a buffer we can check and repair. Re-attach the
+ * ops to the buffer after the read so that when it is rewritten
+ * the CRC is recalculated.
+ *
+ * Returns a positive error on failure, 0 for success, and negative
+ * error if a verifier error occurred and we reread the block without
+ * the verifier successfully.
+ */
+static int
+dir_read_buf(
+	struct xfs_inode	*ip,
+	xfs_dablk_t		bno,
+	xfs_daddr_t		mappedbno,
+	struct xfs_buf		**bpp,
+	const struct xfs_buf_ops *ops)
+{
+	int error;
+	int error2;
+
+	error = libxfs_da_read_buf(NULL, ip, bno, mappedbno, bpp,
+				   XFS_DATA_FORK, ops);
+
+	if (error != EFSBADCRC && error != EFSCORRUPTED)
+		return error;
+
+	error2 = libxfs_da_read_buf(NULL, ip, bno, mappedbno, bpp,
+				   XFS_DATA_FORK, NULL);
+	if (error2)
+		return error2;
+
+	(*bpp)->b_ops = ops;
+	return -error;
+}
+
+/*
  * Returns 0 if the name already exists (ie. a duplicate)
  */
 static int
@@ -1906,15 +1943,22 @@ longform_dir2_check_leaf(
 	int			seeval;
 	struct xfs_dir2_leaf_entry *ents;
 	struct xfs_dir3_icleaf_hdr leafhdr;
+	int			error;
+	int			fixit = 0;
 
 	da_bno = mp->m_dirleafblk;
-	if (libxfs_da_read_buf(NULL, ip, da_bno, -1, &bp, XFS_DATA_FORK,
-				&xfs_dir3_leaf1_buf_ops)) {
+	error = dir_read_buf(ip, da_bno, -1, &bp, &xfs_dir3_leaf1_buf_ops);
+	if (error < 0) {
+		fixit++;
+		error = 0;
+	}
+	if (error) {
 		do_error(
-	_("can't read block %u for directory inode %" PRIu64 "\n"),
-			da_bno, ip->i_ino);
+	_("can't read block %u for directory inode %" PRIu64 ", error %d\n"),
+			da_bno, ip->i_ino, error);
 		/* NOTREACHED */
 	}
+
 	leaf = bp->b_addr;
 	xfs_dir3_leaf_hdr_from_disk(&leafhdr, leaf);
 	ents = xfs_dir3_leaf_ents_p(leaf);
@@ -1951,7 +1995,7 @@ longform_dir2_check_leaf(
 		return 1;
 	}
 	libxfs_putbuf(bp);
-	return 0;
+	return fixit;
 }
 
 /*
@@ -1978,6 +2022,8 @@ longform_dir2_check_node(
 	struct xfs_dir3_icleaf_hdr leafhdr;
 	struct xfs_dir3_icfree_hdr freehdr;
 	__be16			*bests;
+	int			error;
+	int			fixit = 0;
 
 	for (da_bno = mp->m_dirleafblk, next_da_bno = 0;
 			next_da_bno != NULLFILEOFF && da_bno < mp->m_dirfreeblk;
@@ -1993,11 +2039,16 @@ longform_dir2_check_node(
 		 * a node block, then we'll skip it below based on a magic
 		 * number check.
 		 */
-		if (libxfs_da_read_buf(NULL, ip, da_bno, -1, &bp,
-				XFS_DATA_FORK, &xfs_da3_node_buf_ops)) {
+		error = dir_read_buf(ip, da_bno, -1, &bp,
+				     &xfs_da3_node_buf_ops);
+		if (error < 0) {
+			fixit++;
+			error = 0;
+		}
+		if (error) {
 			do_warn(
-	_("can't read leaf block %u for directory inode %" PRIu64 "\n"),
-				da_bno, ip->i_ino);
+	_("can't read leaf block %u for directory inode %" PRIu64 ", error %d\n"),
+				da_bno, ip->i_ino, error);
 			return 1;
 		}
 		leaf = bp->b_addr;
@@ -2016,6 +2067,12 @@ longform_dir2_check_node(
 			libxfs_putbuf(bp);
 			return 1;
 		}
+
+		/*
+		 * If there's a validator error, we need to ensure that we got
+		 * the right ops on the buffer for when we write it back out.
+		 */
+		bp->b_ops = &xfs_dir3_leafn_buf_ops;
 		if (leafhdr.count > xfs_dir3_max_leaf_ents(mp, leaf) ||
 		    leafhdr.count < leafhdr.stale) {
 			do_warn(
@@ -2039,11 +2096,17 @@ longform_dir2_check_node(
 		next_da_bno = da_bno + mp->m_dirblkfsbs - 1;
 		if (bmap_next_offset(NULL, ip, &next_da_bno, XFS_DATA_FORK))
 			break;
-		if (libxfs_da_read_buf(NULL, ip, da_bno, -1, &bp,
-				XFS_DATA_FORK, &xfs_dir3_free_buf_ops)) {
+
+		error = dir_read_buf(ip, da_bno, -1, &bp,
+				     &xfs_dir3_free_buf_ops);
+		if (error < 0) {
+			fixit++;
+			error = 0;
+		}
+		if (error) {
 			do_warn(
-	_("can't read freespace block %u for directory inode %" PRIu64 "\n"),
-				da_bno, ip->i_ino);
+	_("can't read freespace block %u for directory inode %" PRIu64 ", error %d\n"),
+				da_bno, ip->i_ino, error);
 			return 1;
 		}
 		free = bp->b_addr;
@@ -2093,7 +2156,7 @@ longform_dir2_check_node(
 			return 1;
 		}
 	}
-	return 0;
+	return fixit;
 }
 
 /*
@@ -2148,6 +2211,7 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
 	     next_da_bno != NULLFILEOFF && da_bno < mp->m_dirleafblk;
 	     da_bno = (xfs_dablk_t)next_da_bno) {
 		const struct xfs_buf_ops *ops;
+		int			 error;
 
 		next_da_bno = da_bno + mp->m_dirblkfsbs - 1;
 		if (bmap_next_offset(NULL, ip, &next_da_bno, XFS_DATA_FORK))
@@ -2167,11 +2231,17 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
 			ops = &xfs_dir3_block_buf_ops;
 		else
 			ops = &xfs_dir3_data_buf_ops;
-		if (libxfs_da_read_buf(NULL, ip, da_bno, -1, &bplist[db],
-				       XFS_DATA_FORK, ops)) {
+
+		error = dir_read_buf(ip, da_bno, -1, &bplist[db], ops);
+		if (error < 0) {
+			fixit++;
+			error = 0;
+		}
+
+		if (error) {
 			do_warn(
-	_("can't read data block %u for directory inode %" PRIu64 "\n"),
-				da_bno, ino);
+	_("can't read data block %u for directory inode %" PRIu64 " error %d\n"),
+				da_bno, ino, error);
 			*num_illegal += 1;
 
 			/*
@@ -2189,7 +2259,7 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
 				irec, ino_offset, &bplist[db], hashtab,
 				&freetab, da_bno, isblock);
 	}
-	fixit = (*num_illegal != 0) || dir2_is_badino(ino) || *need_dot;
+	fixit |= (*num_illegal != 0) || dir2_is_badino(ino) || *need_dot;
 
 	if (!dotdot_update) {
 		/* check btree and freespace */
-- 
1.9.0

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Re: [PATCH 4/9] repair: detect and correct CRC errors in directory blocks

[Christoph Hellwig]

On Tue, Apr 15, 2014 at 06:24:56PM +1000, Dave Chinner wrote:
> + * Need to handle CRC and validation errors specially here. If
> + * there is a validator error, re-read without the verifier so
> + * that we get a buffer we can check and repair. Re-attach the
> + * ops to the buffer after the read so that when it is rewritten
> + * the CRC is recalculated.
> + *
> + * Returns a positive error on failure, 0 for success, and negative
> + * error if a verifier error occurred and we reread the block without
> + * the verifier successfully.

This comment doesn't come clear to using up the 80 character allowance
:)

I have to say the positive and negative errno convention is a bit
confusing to me.  I'd rather always return 0 if we could read it, and
pass a bool *crc_error instead that indicates if it needs fixing.

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[PATCH 5/9] repair: detect CRC errors in AG headers

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

repair doesn't currently detect verifier errors in AG header
blocks - apart from the primary superblock they are not detected.
They are, fortunately, corrected in the important cases (AGF, AGI
and AGFL) because these structures are rebuilt in phase 5, but if
you run xfs_repair in checking mode it won't report them as bad.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 repair/scan.c | 66 ++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/repair/scan.c b/repair/scan.c
index 1744c32..6c43474 100644
--- a/repair/scan.c
+++ b/repair/scan.c
@@ -1207,28 +1207,31 @@ scan_ag(
 	void		*arg)
 {
 	struct aghdr_cnts *agcnts = arg;
-	xfs_agf_t	*agf;
-	xfs_buf_t	*agfbuf;
+	struct xfs_agf	*agf;
+	struct xfs_buf	*agfbuf = NULL;
 	int		agf_dirty = 0;
-	xfs_agi_t	*agi;
-	xfs_buf_t	*agibuf;
+	struct xfs_agi	*agi;
+	struct xfs_buf	*agibuf = NULL;
 	int		agi_dirty = 0;
-	xfs_sb_t	*sb;
-	xfs_buf_t	*sbbuf;
+	struct xfs_sb	*sb = NULL;
+	struct xfs_buf	*sbbuf = NULL;
 	int		sb_dirty = 0;
 	int		status;
+	char		*objname = NULL;
 
 	sbbuf = libxfs_readbuf(mp->m_dev, XFS_AG_DADDR(mp, agno, XFS_SB_DADDR),
 				XFS_FSS_TO_BB(mp, 1), 0, &xfs_sb_buf_ops);
 	if (!sbbuf)  {
-		do_error(_("can't get root superblock for ag %d\n"), agno);
-		return;
+		objname = _("root superblock");
+		goto out_free;
 	}
+	if (sbbuf->b_error == EFSBADCRC || sbbuf->b_error == EFSCORRUPTED)
+		sb_dirty = 1;
+
 	sb = (xfs_sb_t *)calloc(BBSIZE, 1);
 	if (!sb) {
 		do_error(_("can't allocate memory for superblock\n"));
-		libxfs_putbuf(sbbuf);
-		return;
+		goto out_free;
 	}
 	libxfs_sb_from_disk(sb, XFS_BUF_TO_SBP(sbbuf));
 
@@ -1236,23 +1239,22 @@ scan_ag(
 			XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), 0, &xfs_agf_buf_ops);
 	if (!agfbuf)  {
-		do_error(_("can't read agf block for ag %d\n"), agno);
-		libxfs_putbuf(sbbuf);
-		free(sb);
-		return;
+		objname = _("agf block");
+		goto out_free;
 	}
+	if (agfbuf->b_error == EFSBADCRC || agfbuf->b_error == EFSCORRUPTED)
+		agf_dirty = 1;
 	agf = XFS_BUF_TO_AGF(agfbuf);
 
 	agibuf = libxfs_readbuf(mp->m_dev,
 			XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), 0, &xfs_agi_buf_ops);
 	if (!agibuf)  {
-		do_error(_("can't read agi block for ag %d\n"), agno);
-		libxfs_putbuf(agfbuf);
-		libxfs_putbuf(sbbuf);
-		free(sb);
-		return;
+		objname = _("agi block");
+		goto out_free;
 	}
+	if (agibuf->b_error == EFSBADCRC || agibuf->b_error == EFSCORRUPTED)
+		agi_dirty = 1;
 	agi = XFS_BUF_TO_AGI(agibuf);
 
 	/* fix up bad ag headers */
@@ -1277,7 +1279,7 @@ scan_ag(
 			do_warn(_("would reset bad sb for ag %d\n"), agno);
 		}
 	}
-	if (status & XR_AG_AGF)  {
+	if (agf_dirty || status & XR_AG_AGF)  {
 		if (!no_modify) {
 			do_warn(_("reset bad agf for ag %d\n"), agno);
 			agf_dirty = 1;
@@ -1285,7 +1287,7 @@ scan_ag(
 			do_warn(_("would reset bad agf for ag %d\n"), agno);
 		}
 	}
-	if (status & XR_AG_AGI)  {
+	if (agi_dirty || status & XR_AG_AGI)  {
 		if (!no_modify) {
 			do_warn(_("reset bad agi for ag %d\n"), agno);
 			agi_dirty = 1;
@@ -1295,15 +1297,9 @@ scan_ag(
 	}
 
 	if (status && no_modify)  {
-		libxfs_putbuf(agibuf);
-		libxfs_putbuf(agfbuf);
-		libxfs_putbuf(sbbuf);
-		free(sb);
-
 		do_warn(_("bad uncorrected agheader %d, skipping ag...\n"),
 			agno);
-
-		return;
+		goto out_free;
 	}
 
 	scan_freelist(agf, agcnts);
@@ -1341,6 +1337,20 @@ scan_ag(
 	print_inode_list(i);
 #endif
 	return;
+
+out_free:
+	if (sb)
+		free(sb);
+	if (agibuf)
+		libxfs_putbuf(agibuf);
+	if (agfbuf)
+		libxfs_putbuf(agfbuf);
+	if (sbbuf)
+		libxfs_putbuf(sbbuf);
+	if (objname)
+		do_error(_("can't get %s for ag %d\n"), objname, agno);
+	return;
+
 }
 
 #define SCAN_THREADS 32
-- 
1.9.0

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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Brian Foster]

On Tue, Apr 15, 2014 at 06:24:57PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> repair doesn't currently detect verifier errors in AG header
> blocks - apart from the primary superblock they are not detected.
> They are, fortunately, corrected in the important cases (AGF, AGI
> and AGFL) because these structures are rebuilt in phase 5, but if
> you run xfs_repair in checking mode it won't report them as bad.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  repair/scan.c | 66 ++++++++++++++++++++++++++++++++++-------------------------
>  1 file changed, 38 insertions(+), 28 deletions(-)
> 
> diff --git a/repair/scan.c b/repair/scan.c
> index 1744c32..6c43474 100644
> --- a/repair/scan.c
> +++ b/repair/scan.c
> @@ -1207,28 +1207,31 @@ scan_ag(
>  	void		*arg)
>  {
>  	struct aghdr_cnts *agcnts = arg;
> -	xfs_agf_t	*agf;
> -	xfs_buf_t	*agfbuf;
> +	struct xfs_agf	*agf;
> +	struct xfs_buf	*agfbuf = NULL;
>  	int		agf_dirty = 0;
> -	xfs_agi_t	*agi;
> -	xfs_buf_t	*agibuf;
> +	struct xfs_agi	*agi;
> +	struct xfs_buf	*agibuf = NULL;
>  	int		agi_dirty = 0;
> -	xfs_sb_t	*sb;
> -	xfs_buf_t	*sbbuf;
> +	struct xfs_sb	*sb = NULL;
> +	struct xfs_buf	*sbbuf = NULL;
>  	int		sb_dirty = 0;
>  	int		status;
> +	char		*objname = NULL;
>  
>  	sbbuf = libxfs_readbuf(mp->m_dev, XFS_AG_DADDR(mp, agno, XFS_SB_DADDR),
>  				XFS_FSS_TO_BB(mp, 1), 0, &xfs_sb_buf_ops);
>  	if (!sbbuf)  {
> -		do_error(_("can't get root superblock for ag %d\n"), agno);
> -		return;
> +		objname = _("root superblock");
> +		goto out_free;
>  	}
> +	if (sbbuf->b_error == EFSBADCRC || sbbuf->b_error == EFSCORRUPTED)
> +		sb_dirty = 1;
> +
>  	sb = (xfs_sb_t *)calloc(BBSIZE, 1);
>  	if (!sb) {
>  		do_error(_("can't allocate memory for superblock\n"));
> -		libxfs_putbuf(sbbuf);
> -		return;
> +		goto out_free;
>  	}
>  	libxfs_sb_from_disk(sb, XFS_BUF_TO_SBP(sbbuf));
>  
> @@ -1236,23 +1239,22 @@ scan_ag(
>  			XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
>  			XFS_FSS_TO_BB(mp, 1), 0, &xfs_agf_buf_ops);
>  	if (!agfbuf)  {
> -		do_error(_("can't read agf block for ag %d\n"), agno);
> -		libxfs_putbuf(sbbuf);
> -		free(sb);
> -		return;
> +		objname = _("agf block");
> +		goto out_free;
>  	}
> +	if (agfbuf->b_error == EFSBADCRC || agfbuf->b_error == EFSCORRUPTED)
> +		agf_dirty = 1;
>  	agf = XFS_BUF_TO_AGF(agfbuf);
>  
>  	agibuf = libxfs_readbuf(mp->m_dev,
>  			XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
>  			XFS_FSS_TO_BB(mp, 1), 0, &xfs_agi_buf_ops);
>  	if (!agibuf)  {
> -		do_error(_("can't read agi block for ag %d\n"), agno);
> -		libxfs_putbuf(agfbuf);
> -		libxfs_putbuf(sbbuf);
> -		free(sb);
> -		return;
> +		objname = _("agi block");
> +		goto out_free;
>  	}
> +	if (agibuf->b_error == EFSBADCRC || agibuf->b_error == EFSCORRUPTED)
> +		agi_dirty = 1;
>  	agi = XFS_BUF_TO_AGI(agibuf);
>  
>  	/* fix up bad ag headers */
> @@ -1277,7 +1279,7 @@ scan_ag(
>  			do_warn(_("would reset bad sb for ag %d\n"), agno);
>  		}
>  	}
> -	if (status & XR_AG_AGF)  {
> +	if (agf_dirty || status & XR_AG_AGF)  {
>  		if (!no_modify) {
>  			do_warn(_("reset bad agf for ag %d\n"), agno);
>  			agf_dirty = 1;
> @@ -1285,7 +1287,7 @@ scan_ag(
>  			do_warn(_("would reset bad agf for ag %d\n"), agno);
>  		}
>  	}
> -	if (status & XR_AG_AGI)  {
> +	if (agi_dirty || status & XR_AG_AGI)  {
>  		if (!no_modify) {
>  			do_warn(_("reset bad agi for ag %d\n"), agno);
>  			agi_dirty = 1;

There are a few asserts a bit further down this function that assume
*_dirty is set only when in !no_modify mode. E.g.:

	ASSERT(agi_dirty == 0 || (agi_dirty && !no_modify));

You'll probably want to remove those. Or...

> @@ -1295,15 +1297,9 @@ scan_ag(
>  	}
>  
>  	if (status && no_modify)  {
> -		libxfs_putbuf(agibuf);
> -		libxfs_putbuf(agfbuf);
> -		libxfs_putbuf(sbbuf);
> -		free(sb);
> -
>  		do_warn(_("bad uncorrected agheader %d, skipping ag...\n"),
>  			agno);
> -
> -		return;
> +		goto out_free;
>  	}

Would we want to skip the ag, as such, on a CRC error in no_modify mode?
If so, perhaps we could set the status variable on crc errors and
bitwise or the value returned from verify_set_agheader().

Brian

>  
>  	scan_freelist(agf, agcnts);
> @@ -1341,6 +1337,20 @@ scan_ag(
>  	print_inode_list(i);
>  #endif
>  	return;
> +
> +out_free:
> +	if (sb)
> +		free(sb);
> +	if (agibuf)
> +		libxfs_putbuf(agibuf);
> +	if (agfbuf)
> +		libxfs_putbuf(agfbuf);
> +	if (sbbuf)
> +		libxfs_putbuf(sbbuf);
> +	if (objname)
> +		do_error(_("can't get %s for ag %d\n"), objname, agno);
> +	return;
> +
>  }
>  
>  #define SCAN_THREADS 32
> -- 
> 1.9.0
> 
> _______________________________________________
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> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Dave Chinner]

On Tue, Apr 15, 2014 at 03:40:29PM -0400, Brian Foster wrote:
> On Tue, Apr 15, 2014 at 06:24:57PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > repair doesn't currently detect verifier errors in AG header
> > blocks - apart from the primary superblock they are not detected.
> > They are, fortunately, corrected in the important cases (AGF, AGI
> > and AGFL) because these structures are rebuilt in phase 5, but if
> > you run xfs_repair in checking mode it won't report them as bad.
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
....
> > @@ -1285,7 +1287,7 @@ scan_ag(
> >  			do_warn(_("would reset bad agf for ag %d\n"), agno);
> >  		}
> >  	}
> > -	if (status & XR_AG_AGI)  {
> > +	if (agi_dirty || status & XR_AG_AGI)  {
> >  		if (!no_modify) {
> >  			do_warn(_("reset bad agi for ag %d\n"), agno);
> >  			agi_dirty = 1;
> 
> There are a few asserts a bit further down this function that assume
> *_dirty is set only when in !no_modify mode. E.g.:
> 
> 	ASSERT(agi_dirty == 0 || (agi_dirty && !no_modify));
> 
> You'll probably want to remove those. Or...

I thought I caught all of those...

> 
> > @@ -1295,15 +1297,9 @@ scan_ag(
> >  	}
> >  
> >  	if (status && no_modify)  {
> > -		libxfs_putbuf(agibuf);
> > -		libxfs_putbuf(agfbuf);
> > -		libxfs_putbuf(sbbuf);
> > -		free(sb);
> > -
> >  		do_warn(_("bad uncorrected agheader %d, skipping ag...\n"),
> >  			agno);
> > -
> > -		return;
> > +		goto out_free;
> >  	}
> 
> Would we want to skip the ag, as such, on a CRC error in no_modify mode?
> If so, perhaps we could set the status variable on crc errors and
> bitwise or the value returned from verify_set_agheader().

I figured that for CRC errors we really should try to validate
everything if we can. If nothing else fails the validation, then it
might be a bit flip in an unused portion of the sector and in that
case we can actually continue onwards. IOWs, a CRC error is not
necessarily fatal....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Christoph Hellwig]

On Tue, Apr 15, 2014 at 06:24:57PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> repair doesn't currently detect verifier errors in AG header
> blocks - apart from the primary superblock they are not detected.
> They are, fortunately, corrected in the important cases (AGF, AGI
> and AGFL) because these structures are rebuilt in phase 5, but if
> you run xfs_repair in checking mode it won't report them as bad.

Shouldn't we apply the same scheme as for directories here, that is if
it fails with a verifier error re-read without the verifier and then
still do the full check as well?

Btw, it might make sense to have special read_buf variants in libxfs
that always return a valid buffer even if the verifier fails, just
telling us about it without having to re-read.

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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Dave Chinner]

On Mon, Apr 21, 2014 at 12:11:06AM -0700, Christoph Hellwig wrote:
> On Tue, Apr 15, 2014 at 06:24:57PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > repair doesn't currently detect verifier errors in AG header
> > blocks - apart from the primary superblock they are not detected.
> > They are, fortunately, corrected in the important cases (AGF, AGI
> > and AGFL) because these structures are rebuilt in phase 5, but if
> > you run xfs_repair in checking mode it won't report them as bad.
> 
> Shouldn't we apply the same scheme as for directories here, that is if
> it fails with a verifier error re-read without the verifier and then
> still do the full check as well?

The directory code is the special case - it uses xfs_trans_read_buf*
interfaces, which return either a good buffer with no error or an
error with no buffer. Hence for the directory code, we have to
re-read the buffer without the verifier to grab the unchecked buffer
from the cache when the verifier detects an error.

> Btw, it might make sense to have special read_buf variants in libxfs
> that always return a valid buffer even if the verifier fails, just
> telling us about it without having to re-read.

That's exactly what they do now - you get the xfs_buf, the data in
bp->b_addr and the verifier error in bp->b_error all in one call.

Cheers,

Dave.
-- 
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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Christoph Hellwig]

On Tue, Apr 22, 2014 at 09:35:12AM +1000, Dave Chinner wrote:
> > Shouldn't we apply the same scheme as for directories here, that is if
> > it fails with a verifier error re-read without the verifier and then
> > still do the full check as well?
> 
> The directory code is the special case - it uses xfs_trans_read_buf*
> interfaces, which return either a good buffer with no error or an
> error with no buffer. Hence for the directory code, we have to
> re-read the buffer without the verifier to grab the unchecked buffer
> from the cache when the verifier detects an error.

How about just having a variant of xfs_da_read_buf that doesn't use
xfs_trans_read_buf *?  xfs_da_read_buf is pretty simple, especially
when removing the magic test that has been superceeded by the verifiers.

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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Dave Chinner]

On Mon, Apr 21, 2014 at 11:47:37PM -0700, Christoph Hellwig wrote:
> On Tue, Apr 22, 2014 at 09:35:12AM +1000, Dave Chinner wrote:
> > > Shouldn't we apply the same scheme as for directories here, that is if
> > > it fails with a verifier error re-read without the verifier and then
> > > still do the full check as well?
> > 
> > The directory code is the special case - it uses xfs_trans_read_buf*
> > interfaces, which return either a good buffer with no error or an
> > error with no buffer. Hence for the directory code, we have to
> > re-read the buffer without the verifier to grab the unchecked buffer
> > from the cache when the verifier detects an error.
> 
> How about just having a variant of xfs_da_read_buf that doesn't use
> xfs_trans_read_buf *?  xfs_da_read_buf is pretty simple, especially
> when removing the magic test that has been superceeded by the verifiers.

Right now I ijust want to keep the change as small as possible and
get a release out.

Yes, I agree there's much more cleanup that is needed in this code,
but at this point is seems unnecessary and doesn't matter for the
purpose of providing this functionality initially.  We have to
provide the same functionality for the kernel code for it to be able
to handle CRC errors sanely, and so we're going to need to
restructure xfs_trans_read_buf() to handle it. in doing this, we
solve the libxfs problem, too, because what we do to the kernel code
will flow on to userspace...

So really, I'd prefer to leave the userspace code doing this retry
for this one piece of infrastructure and do all the major
restructing of the directory buffer read code in the kernel code
first. That way we can pick up all the changes for userspace when
the libxfs code is updated.

Keep in mind that right now we've got a *lot* of updates from the
kernel to the libxfs code pending that are stalled waiting for a
release to be done...

Cheers,

Dave.
-- 
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david@fromorbit.com

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Re: [PATCH 5/9] repair: detect CRC errors in AG headers

[Christoph Hellwig]

On Tue, Apr 22, 2014 at 07:10:43PM +1000, Dave Chinner wrote:
> Right now I ijust want to keep the change as small as possible and
> get a release out.

Oh well.  I'll probably ACK it next time it comes around.  I think the
series needs enough changes for a resend anyway.

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[PATCH 6/9] repair: report AG btree verifier errors

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

When we scan the filesystem freespace and inode maps in phase 2, we
don't report CRC errors that are found. We don't really care from a
repair perspective, because the trees are completely rebuilt from
the ground up in phase 5, but froma checking perspective we need to
inform the user that we found inconsistencies.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 repair/scan.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/repair/scan.c b/repair/scan.c
index 6c43474..75b4b70 100644
--- a/repair/scan.c
+++ b/repair/scan.c
@@ -82,6 +82,12 @@ scan_sbtree(
 		do_error(_("can't read btree block %d/%d\n"), agno, root);
 		return;
 	}
+	if (bp->b_error == EFSBADCRC || bp->b_error == EFSCORRUPTED) {
+		do_warn(_("btree block %d/%d is suspect, error %d\n"),
+			agno, root, bp->b_error);
+		suspect = 1;
+	}
+
 	(*func)(XFS_BUF_TO_BLOCK(bp), nlevels - 1, root, agno, suspect,
 							isroot, magic, priv);
 	libxfs_putbuf(bp);
@@ -123,6 +129,7 @@ scan_lbtree(
 	xfs_buf_t	*bp;
 	int		err;
 	int		dirty = 0;
+	bool		badcrc = false;
 
 	bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, root),
 		      XFS_FSB_TO_BB(mp, 1), 0, ops);
@@ -132,14 +139,25 @@ scan_lbtree(
 			XFS_FSB_TO_AGBNO(mp, root));
 		return(1);
 	}
+
+	/*
+	 * only check for bad CRC here - caller will determine if there
+	 * is a corruption or not and whether it got corrected and so needs
+	 * writing back. CRC errors always imply we need to write the block.
+	 */
+	if (bp->b_error == EFSBADCRC) {
+		do_warn(_("btree block %d/%d is suspect, error %d\n"),
+			XFS_FSB_TO_AGNO(mp, root),
+			XFS_FSB_TO_AGBNO(mp, root), bp->b_error);
+		badcrc = true;
+	}
+
 	err = (*func)(XFS_BUF_TO_BLOCK(bp), nlevels - 1,
 			type, whichfork, root, ino, tot, nex, blkmapp,
 			bm_cursor, isroot, check_dups, &dirty,
 			magic);
 
-	ASSERT(dirty == 0 || (dirty && !no_modify));
-
-	if (dirty && !no_modify)
+	if ((dirty || badcrc) && !no_modify)
 		libxfs_writebuf(bp, 0);
 	else
 		libxfs_putbuf(bp);
@@ -1066,6 +1084,9 @@ scan_freelist(
 		do_abort(_("can't read agfl block for ag %d\n"), agno);
 		return;
 	}
+	if (agflbuf->b_error == EFSBADCRC)
+		do_warn(_("agfl has bad CRC for ag %d\n"), agno);
+
 	freelist = XFS_BUF_TO_AGFL_BNO(mp, agflbuf);
 	i = be32_to_cpu(agf->agf_flfirst);
 
-- 
1.9.0

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Re: [PATCH 6/9] repair: report AG btree verifier errors

[Brian Foster]

On Tue, Apr 15, 2014 at 06:24:58PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> When we scan the filesystem freespace and inode maps in phase 2, we
> don't report CRC errors that are found. We don't really care from a
> repair perspective, because the trees are completely rebuilt from
> the ground up in phase 5, but froma checking perspective we need to
> inform the user that we found inconsistencies.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  repair/scan.c | 27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/repair/scan.c b/repair/scan.c
> index 6c43474..75b4b70 100644
> --- a/repair/scan.c
> +++ b/repair/scan.c
> @@ -82,6 +82,12 @@ scan_sbtree(
>  		do_error(_("can't read btree block %d/%d\n"), agno, root);
>  		return;
>  	}
> +	if (bp->b_error == EFSBADCRC || bp->b_error == EFSCORRUPTED) {
> +		do_warn(_("btree block %d/%d is suspect, error %d\n"),
> +			agno, root, bp->b_error);
> +		suspect = 1;
> +	}
> +
>  	(*func)(XFS_BUF_TO_BLOCK(bp), nlevels - 1, root, agno, suspect,
>  							isroot, magic, priv);
>  	libxfs_putbuf(bp);
> @@ -123,6 +129,7 @@ scan_lbtree(
>  	xfs_buf_t	*bp;
>  	int		err;
>  	int		dirty = 0;
> +	bool		badcrc = false;
>  
>  	bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, root),
>  		      XFS_FSB_TO_BB(mp, 1), 0, ops);
> @@ -132,14 +139,25 @@ scan_lbtree(
>  			XFS_FSB_TO_AGBNO(mp, root));
>  		return(1);
>  	}
> +
> +	/*
> +	 * only check for bad CRC here - caller will determine if there
> +	 * is a corruption or not and whether it got corrected and so needs
> +	 * writing back. CRC errors always imply we need to write the block.
> +	 */
> +	if (bp->b_error == EFSBADCRC) {
> +		do_warn(_("btree block %d/%d is suspect, error %d\n"),
> +			XFS_FSB_TO_AGNO(mp, root),
> +			XFS_FSB_TO_AGBNO(mp, root), bp->b_error);
> +		badcrc = true;
> +	}
> +
>  	err = (*func)(XFS_BUF_TO_BLOCK(bp), nlevels - 1,
>  			type, whichfork, root, ino, tot, nex, blkmapp,
>  			bm_cursor, isroot, check_dups, &dirty,
>  			magic);
>  
> -	ASSERT(dirty == 0 || (dirty && !no_modify));
> -

Here we remove the dirty assert, but don't change the semantics of dirty
(we use badcrc).

Brian

> -	if (dirty && !no_modify)
> +	if ((dirty || badcrc) && !no_modify)
>  		libxfs_writebuf(bp, 0);
>  	else
>  		libxfs_putbuf(bp);
> @@ -1066,6 +1084,9 @@ scan_freelist(
>  		do_abort(_("can't read agfl block for ag %d\n"), agno);
>  		return;
>  	}
> +	if (agflbuf->b_error == EFSBADCRC)
> +		do_warn(_("agfl has bad CRC for ag %d\n"), agno);
> +
>  	freelist = XFS_BUF_TO_AGFL_BNO(mp, agflbuf);
>  	i = be32_to_cpu(agf->agf_flfirst);
>  
> -- 
> 1.9.0
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 6/9] repair: report AG btree verifier errors

[Dave Chinner]

On Tue, Apr 15, 2014 at 03:40:48PM -0400, Brian Foster wrote:
> On Tue, Apr 15, 2014 at 06:24:58PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > When we scan the filesystem freespace and inode maps in phase 2, we
> > don't report CRC errors that are found. We don't really care from a
> > repair perspective, because the trees are completely rebuilt from
> > the ground up in phase 5, but froma checking perspective we need to
> > inform the user that we found inconsistencies.
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  repair/scan.c | 27 ++++++++++++++++++++++++---
> >  1 file changed, 24 insertions(+), 3 deletions(-)
> > 
> > diff --git a/repair/scan.c b/repair/scan.c
> > index 6c43474..75b4b70 100644
> > --- a/repair/scan.c
> > +++ b/repair/scan.c
> > @@ -82,6 +82,12 @@ scan_sbtree(
> >  		do_error(_("can't read btree block %d/%d\n"), agno, root);
> >  		return;
> >  	}
> > +	if (bp->b_error == EFSBADCRC || bp->b_error == EFSCORRUPTED) {
> > +		do_warn(_("btree block %d/%d is suspect, error %d\n"),
> > +			agno, root, bp->b_error);
> > +		suspect = 1;
> > +	}
> > +
> >  	(*func)(XFS_BUF_TO_BLOCK(bp), nlevels - 1, root, agno, suspect,
> >  							isroot, magic, priv);
> >  	libxfs_putbuf(bp);
> > @@ -123,6 +129,7 @@ scan_lbtree(
> >  	xfs_buf_t	*bp;
> >  	int		err;
> >  	int		dirty = 0;
> > +	bool		badcrc = false;
> >  
> >  	bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, root),
> >  		      XFS_FSB_TO_BB(mp, 1), 0, ops);
> > @@ -132,14 +139,25 @@ scan_lbtree(
> >  			XFS_FSB_TO_AGBNO(mp, root));
> >  		return(1);
> >  	}
> > +
> > +	/*
> > +	 * only check for bad CRC here - caller will determine if there
> > +	 * is a corruption or not and whether it got corrected and so needs
> > +	 * writing back. CRC errors always imply we need to write the block.
> > +	 */
> > +	if (bp->b_error == EFSBADCRC) {
> > +		do_warn(_("btree block %d/%d is suspect, error %d\n"),
> > +			XFS_FSB_TO_AGNO(mp, root),
> > +			XFS_FSB_TO_AGBNO(mp, root), bp->b_error);
> > +		badcrc = true;
> > +	}
> > +
> >  	err = (*func)(XFS_BUF_TO_BLOCK(bp), nlevels - 1,
> >  			type, whichfork, root, ino, tot, nex, blkmapp,
> >  			bm_cursor, isroot, check_dups, &dirty,
> >  			magic);
> >  
> > -	ASSERT(dirty == 0 || (dirty && !no_modify));
> > -
> 
> Here we remove the dirty assert, but don't change the semantics of dirty
> (we use badcrc).

Yeah, I went back and changed the mechanism for correcting pure
CRC errors not to use the dirty flag. I'll re-instate the assert...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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[PATCH 7/9] repair: remove more dirv1 leftovers

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

get_bmapi() and it's children were only called by dirv1 code. There
are no current callers, so remove them.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 repair/dinode.c | 239 --------------------------------------------------------
 repair/dinode.h |   6 --
 2 files changed, 245 deletions(-)

diff --git a/repair/dinode.c b/repair/dinode.c
index 48f17ac..b086bec 100644
--- a/repair/dinode.c
+++ b/repair/dinode.c
@@ -870,245 +870,6 @@ get_agino_buf(xfs_mount_t	 *mp,
 }
 
 /*
- * these next routines return the filesystem blockno of the
- * block containing the block "bno" in the file whose bmap
- * tree (or extent list) is rooted by "rootblock".
- *
- * the next routines are utility routines for the third
- * routine, get_bmapi().
- *
- * NOTE: getfunc_extlist only used by dirv1 checking code
- */
-static xfs_dfsbno_t
-getfunc_extlist(xfs_mount_t		*mp,
-		xfs_ino_t		ino,
-		xfs_dinode_t		*dip,
-		xfs_dfiloff_t		bno,
-		int			whichfork)
-{
-	xfs_bmbt_irec_t		irec;
-	xfs_dfsbno_t		final_fsbno = NULLDFSBNO;
-	xfs_bmbt_rec_t		*rootblock = (xfs_bmbt_rec_t *)
-						XFS_DFORK_PTR(dip, whichfork);
-	xfs_extnum_t		nextents = XFS_DFORK_NEXTENTS(dip, whichfork);
-	int			i;
-
-	for (i = 0; i < nextents; i++)  {
-		libxfs_bmbt_disk_get_all(rootblock + i, &irec);
-		if (irec.br_startoff <= bno &&
-				bno < irec.br_startoff + irec.br_blockcount) {
-			final_fsbno = bno - irec.br_startoff + irec.br_startblock;
-			break;
-		}
-	}
-
-	return(final_fsbno);
-}
-
-/*
- * NOTE: getfunc_btree only used by dirv1 checking code... 
- */
-static xfs_dfsbno_t
-getfunc_btree(xfs_mount_t		*mp,
-		xfs_ino_t		ino,
-		xfs_dinode_t		*dip,
-		xfs_dfiloff_t		bno,
-		int			whichfork)
-{
-	int			i;
-#ifdef DEBUG
-	int			prev_level;
-#endif
-	int			found;
-	int			numrecs;
-	xfs_bmbt_rec_t		*rec;
-	xfs_bmbt_irec_t		irec;
-	xfs_bmbt_ptr_t		*pp;
-	xfs_bmbt_key_t		*key;
-	xfs_bmdr_key_t		*rkey;
-	xfs_bmdr_ptr_t		*rp;
-	xfs_dfsbno_t		fsbno;
-	xfs_buf_t		*bp;
-	xfs_dfsbno_t		final_fsbno = NULLDFSBNO;
-	struct xfs_btree_block	*block;
-	xfs_bmdr_block_t	*rootblock = (xfs_bmdr_block_t *)
-						XFS_DFORK_PTR(dip, whichfork);
-
-	ASSERT(rootblock->bb_level != 0);
-	/*
-	 * deal with root block, it's got a slightly different
-	 * header structure than interior nodes.  We know that
-	 * a btree should have at least 2 levels otherwise it
-	 * would be an extent list.
-	 */
-	rkey = XFS_BMDR_KEY_ADDR(rootblock, 1);
-	rp = XFS_BMDR_PTR_ADDR(rootblock, 1,
-		xfs_bmdr_maxrecs(mp, XFS_DFORK_SIZE(dip, mp, whichfork), 1));
-	found = -1;
-	for (i = 0; i < be16_to_cpu(rootblock->bb_numrecs) - 1; i++) {
-		if (be64_to_cpu(rkey[i].br_startoff) <= bno && 
-				bno < be64_to_cpu(rkey[i + 1].br_startoff)) {
-			found = i;
-			break;
-		}
-	}
-	if (i == be16_to_cpu(rootblock->bb_numrecs) - 1 && 
-				bno >= be64_to_cpu(rkey[i].br_startoff))
-		found = i;
-
-	ASSERT(found != -1);
-
-	fsbno = be64_to_cpu(rp[found]);
-
-	ASSERT(verify_dfsbno(mp, fsbno));
-
-	bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, fsbno),
-				XFS_FSB_TO_BB(mp, 1), 0, NULL);
-	if (!bp) {
-		do_error(_("cannot read bmap block %" PRIu64 "\n"), fsbno);
-		return(NULLDFSBNO);
-	}
-	block = XFS_BUF_TO_BLOCK(bp);
-	numrecs = be16_to_cpu(block->bb_numrecs);
-
-	/*
-	 * ok, now traverse any interior btree nodes
-	 */
-#ifdef DEBUG
-	prev_level = be16_to_cpu(block->bb_level);
-#endif
-
-	while (be16_to_cpu(block->bb_level) > 0)  {
-#ifdef DEBUG
-		ASSERT(be16_to_cpu(block->bb_level) < prev_level);
-
-		prev_level = be16_to_cpu(block->bb_level);
-#endif
-		if (numrecs > mp->m_bmap_dmxr[1]) {
-			do_warn(
-_("# of bmap records in inode %" PRIu64 " exceeds max (%u, max - %u)\n"),
-				ino, numrecs,
-				mp->m_bmap_dmxr[1]);
-			libxfs_putbuf(bp);
-			return(NULLDFSBNO);
-		}
-		if (verbose && numrecs < mp->m_bmap_dmnr[1]) {
-			do_warn(
-_("- # of bmap records in inode %" PRIu64 " less than minimum (%u, min - %u), proceeding ...\n"),
-				ino, numrecs, mp->m_bmap_dmnr[1]);
-		}
-		key = XFS_BMBT_KEY_ADDR(mp, block, 1);
-		pp = XFS_BMBT_PTR_ADDR(mp, block, 1, mp->m_bmap_dmxr[1]);
-		for (found = -1, i = 0; i < numrecs - 1; i++) {
-			if (be64_to_cpu(key[i].br_startoff) <= bno && bno < 
-					be64_to_cpu(key[i + 1].br_startoff)) {
-				found = i;
-				break;
-			}
-		}
-		if (i == numrecs - 1 && bno >= be64_to_cpu(key[i].br_startoff))
-			found = i;
-
-		ASSERT(found != -1);
-		fsbno = be64_to_cpu(pp[found]);
-
-		ASSERT(verify_dfsbno(mp, fsbno));
-
-		/*
-		 * release current btree block and read in the
-		 * next btree block to be traversed
-		 */
-		libxfs_putbuf(bp);
-		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, fsbno),
-					XFS_FSB_TO_BB(mp, 1), 0, NULL);
-		if (!bp) {
-			do_error(_("cannot read bmap block %" PRIu64 "\n"),
-				fsbno);
-			return(NULLDFSBNO);
-		}
-		block = XFS_BUF_TO_BLOCK(bp);
-		numrecs = be16_to_cpu(block->bb_numrecs);
-	}
-
-	/*
-	 * current block must be a leaf block
-	 */
-	ASSERT(be16_to_cpu(block->bb_level) == 0);
-	if (numrecs > mp->m_bmap_dmxr[0]) {
-		do_warn(
-_("# of bmap records in inode %" PRIu64 " greater than maximum (%u, max - %u)\n"),
-			ino, numrecs, mp->m_bmap_dmxr[0]);
-		libxfs_putbuf(bp);
-		return(NULLDFSBNO);
-	}
-	if (verbose && numrecs < mp->m_bmap_dmnr[0])
-		do_warn(
-_("- # of bmap records in inode %" PRIu64 " less than minimum (%u, min - %u), continuing...\n"),
-			ino, numrecs, mp->m_bmap_dmnr[0]);
-
-	rec = XFS_BMBT_REC_ADDR(mp, block, 1);
-	for (i = 0; i < numrecs; i++)  {
-		libxfs_bmbt_disk_get_all(rec + i, &irec);
-		if (irec.br_startoff <= bno &&
-				bno < irec.br_startoff + irec.br_blockcount) {
-			final_fsbno = bno - irec.br_startoff +
-							irec.br_startblock;
-			break;
-		}
-	}
-	libxfs_putbuf(bp);
-
-	if (final_fsbno == NULLDFSBNO)
-		do_warn(_("could not map block %" PRIu64 "\n"), bno);
-
-	return(final_fsbno);
-}
-
-/*
- * this could be smarter.  maybe we should have an open inode
- * routine that would get the inode buffer and return back
- * an inode handle.  I'm betting for the moment that this
- * is used only by the directory and attribute checking code
- * and that the avl tree find and buffer cache search are
- * relatively cheap.  If they're too expensive, we'll just
- * have to fix this and add an inode handle to the da btree
- * cursor.
- *
- * caller is responsible for checking doubly referenced blocks
- * and references to holes
- *
- * NOTE: get_bmapi only used by dirv1 checking code
- */
-xfs_dfsbno_t
-get_bmapi(xfs_mount_t *mp, xfs_dinode_t *dino_p,
-		xfs_ino_t ino_num, xfs_dfiloff_t bno, int whichfork)
-{
-	xfs_dfsbno_t		fsbno;
-
-	switch (XFS_DFORK_FORMAT(dino_p, whichfork)) {
-	case XFS_DINODE_FMT_EXTENTS:
-		fsbno = getfunc_extlist(mp, ino_num, dino_p, bno, whichfork);
-		break;
-	case XFS_DINODE_FMT_BTREE:
-		fsbno = getfunc_btree(mp, ino_num, dino_p, bno, whichfork);
-		break;
-	case XFS_DINODE_FMT_LOCAL:
-		do_error(_("get_bmapi() called for local inode %" PRIu64 "\n"),
-			ino_num);
-		fsbno = NULLDFSBNO;
-		break;
-	default:
-		/*
-		 * shouldn't happen
-		 */
-		do_error(_("bad inode format for inode %" PRIu64 "\n"), ino_num);
-		fsbno = NULLDFSBNO;
-	}
-
-	return(fsbno);
-}
-
-/*
  * higher level inode processing stuff starts here:
  * first, one utility routine for each type of inode
  */
diff --git a/repair/dinode.h b/repair/dinode.h
index 5ee51ca..80f3e4e 100644
--- a/repair/dinode.h
+++ b/repair/dinode.h
@@ -119,12 +119,6 @@ get_agino_buf(xfs_mount_t	*mp,
 		xfs_agino_t	agino,
 		xfs_dinode_t	**dipp);
 
-xfs_dfsbno_t
-get_bmapi(xfs_mount_t		*mp,
-		xfs_dinode_t	*dip,
-		xfs_ino_t	ino_num,
-		xfs_dfiloff_t	bno,
-		int             whichfork );
 
 void dinode_bmbt_translation_init(void);
 char * get_forkname(int whichfork);
-- 
1.9.0

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Re: [PATCH 7/9] repair: remove more dirv1 leftovers

[Brian Foster]

On Tue, Apr 15, 2014 at 06:24:59PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> get_bmapi() and it's children were only called by dirv1 code. There
> are no current callers, so remove them.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  repair/dinode.c | 239 --------------------------------------------------------
>  repair/dinode.h |   6 --
>  2 files changed, 245 deletions(-)
> 
> diff --git a/repair/dinode.c b/repair/dinode.c
> index 48f17ac..b086bec 100644
> --- a/repair/dinode.c
> +++ b/repair/dinode.c
...
> -xfs_dfsbno_t
> -get_bmapi(xfs_mount_t *mp, xfs_dinode_t *dino_p,
> -		xfs_ino_t ino_num, xfs_dfiloff_t bno, int whichfork)
> -{
> -	xfs_dfsbno_t		fsbno;
> -
> -	switch (XFS_DFORK_FORMAT(dino_p, whichfork)) {
> -	case XFS_DINODE_FMT_EXTENTS:
> -		fsbno = getfunc_extlist(mp, ino_num, dino_p, bno, whichfork);
> -		break;
> -	case XFS_DINODE_FMT_BTREE:
> -		fsbno = getfunc_btree(mp, ino_num, dino_p, bno, whichfork);
> -		break;
> -	case XFS_DINODE_FMT_LOCAL:
> -		do_error(_("get_bmapi() called for local inode %" PRIu64 "\n"),
> -			ino_num);

I'm not quite familiar with how we manage the .po translation files, but
FYI this string appears in a couple of them. Not sure whether there is
value in keeping the translation around. The string does include the
specific function name.

Brian

> -		fsbno = NULLDFSBNO;
> -		break;
> -	default:
> -		/*
> -		 * shouldn't happen
> -		 */
> -		do_error(_("bad inode format for inode %" PRIu64 "\n"), ino_num);
> -		fsbno = NULLDFSBNO;
> -	}
> -
> -	return(fsbno);
> -}
> -
> -/*
>   * higher level inode processing stuff starts here:
>   * first, one utility routine for each type of inode
>   */
> diff --git a/repair/dinode.h b/repair/dinode.h
> index 5ee51ca..80f3e4e 100644
> --- a/repair/dinode.h
> +++ b/repair/dinode.h
> @@ -119,12 +119,6 @@ get_agino_buf(xfs_mount_t	*mp,
>  		xfs_agino_t	agino,
>  		xfs_dinode_t	**dipp);
>  
> -xfs_dfsbno_t
> -get_bmapi(xfs_mount_t		*mp,
> -		xfs_dinode_t	*dip,
> -		xfs_ino_t	ino_num,
> -		xfs_dfiloff_t	bno,
> -		int             whichfork );
>  
>  void dinode_bmbt_translation_init(void);
>  char * get_forkname(int whichfork);
> -- 
> 1.9.0
> 
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Re: [PATCH 7/9] repair: remove more dirv1 leftovers

[Christoph Hellwig]

On Wed, Apr 16, 2014 at 09:23:34AM -0400, Brian Foster wrote:
> I'm not quite familiar with how we manage the .po translation files, but
> FYI this string appears in a couple of them. Not sure whether there is
> value in keeping the translation around. The string does include the
> specific function name.

They are dead but harmless after the original ones are removed.  The
next time the translators generate the translatable strings they won't
be in there, and they should be removed with the translation update.

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Re: [PATCH 7/9] repair: remove more dirv1 leftovers

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

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[PATCH 8/9] repair: handle remote sylmlink CRC errors

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

We can't really repair broken symlink buffer contents, but we can at
least warn about it and correct the CRC error so the symlink is
again readable.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 repair/dinode.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/repair/dinode.c b/repair/dinode.c
index b086bec..51863c4 100644
--- a/repair/dinode.c
+++ b/repair/dinode.c
@@ -1254,6 +1254,7 @@ process_symlink_remote(
 	while (pathlen > 0) {
 		int	blk_cnt = 1;
 		int	byte_cnt;
+		int	dirty = 0;
 
 		fsbno = blkmap_get(blkmap, i);
 		if (fsbno == NULLDFSBNO) {
@@ -1284,6 +1285,12 @@ _("cannot read inode %" PRIu64 ", file block %d, disk block %" PRIu64 "\n"),
 				lino, i, fsbno);
 			return 1;
 		}
+		if (bp->b_error == EFSBADCRC) {
+			do_warn(
+_("Bad symlink buffer CRC block %" PRIu64 ", inode %" PRIu64 ".\n"
+  "Correcting CRC, but symlink may be bad.\n"), fsbno, lino);
+			dirty = 1;
+		}
 
 		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 		byte_cnt = MIN(pathlen, byte_cnt);
@@ -1307,7 +1314,10 @@ _("bad symlink header ino %" PRIu64 ", file block %d, disk block %" PRIu64 "\n")
 		offset += byte_cnt;
 		i++;
 
-		libxfs_putbuf(bp);
+		if (dirty)
+			libxfs_writebuf(bp, 0);
+		else
+			libxfs_putbuf(bp);
 	}
 	return 0;
 }
-- 
1.9.0

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Re: [PATCH 8/9] repair: handle remote sylmlink CRC errors

[Brian Foster]

On Tue, Apr 15, 2014 at 06:25:00PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 

Just a couple nits... otherwise it looks good to me. There's a typo in
the patch subject...

> We can't really repair broken symlink buffer contents, but we can at
> least warn about it and correct the CRC error so the symlink is
> again readable.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  repair/dinode.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/repair/dinode.c b/repair/dinode.c
> index b086bec..51863c4 100644
> --- a/repair/dinode.c
> +++ b/repair/dinode.c
> @@ -1254,6 +1254,7 @@ process_symlink_remote(
>  	while (pathlen > 0) {
>  		int	blk_cnt = 1;
>  		int	byte_cnt;
> +		int	dirty = 0;
>  
>  		fsbno = blkmap_get(blkmap, i);
>  		if (fsbno == NULLDFSBNO) {
> @@ -1284,6 +1285,12 @@ _("cannot read inode %" PRIu64 ", file block %d, disk block %" PRIu64 "\n"),
>  				lino, i, fsbno);
>  			return 1;
>  		}
> +		if (bp->b_error == EFSBADCRC) {
> +			do_warn(
> +_("Bad symlink buffer CRC block %" PRIu64 ", inode %" PRIu64 ".\n"
     "Bad symlink buffer CRC, block ..."

... and sticking a comma or some separator in that message makes it a
little easier to read, IMO.

Brian

> +  "Correcting CRC, but symlink may be bad.\n"), fsbno, lino);
> +			dirty = 1;
> +		}
>  
>  		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
>  		byte_cnt = MIN(pathlen, byte_cnt);
> @@ -1307,7 +1314,10 @@ _("bad symlink header ino %" PRIu64 ", file block %d, disk block %" PRIu64 "\n")
>  		offset += byte_cnt;
>  		i++;
>  
> -		libxfs_putbuf(bp);
> +		if (dirty)
> +			libxfs_writebuf(bp, 0);
> +		else
> +			libxfs_putbuf(bp);
>  	}
>  	return 0;
>  }
> -- 
> 1.9.0
> 
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> http://oss.sgi.com/mailman/listinfo/xfs

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[PATCH 9/9] repair: detect and handle attribute tree CRC errors

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Currently the attribute code will not detect and correct errors in
the attribute tree. It also fails to validate the CRCs and headers
on remote attribute blocks. Ensure that all the attribute blocks are
CRC checked and that the processing functions understand the correct
block formats for decoding.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 repair/attr_repair.c | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/repair/attr_repair.c b/repair/attr_repair.c
index ba85ac2..13ec90e 100644
--- a/repair/attr_repair.c
+++ b/repair/attr_repair.c
@@ -611,6 +611,8 @@ verify_da_path(xfs_mount_t	*mp,
 		ASSERT(cursor->level[this_level].dirty == 0 ||
 			(cursor->level[this_level].dirty && !no_modify));
 
+		if (bp->b_error == EFSBADCRC)
+			cursor->level[this_level].dirty++;
 		if (cursor->level[this_level].dirty && !no_modify)
 			libxfs_writebuf(cursor->level[this_level].bp, 0);
 		else
@@ -974,6 +976,10 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t ino, blkmap_t *blkmap,
 	xfs_dfsbno_t	bno;
 	xfs_buf_t	*bp;
 	int		clearit = 0, i = 0, length = 0, amountdone = 0;
+	int		hdrsize = 0;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		hdrsize = sizeof(struct xfs_attr3_rmt_hdr);
 
 	/* ASSUMPTION: valuelen is a valid number, so use it for looping */
 	/* Note that valuelen is not a multiple of blocksize */
@@ -986,16 +992,26 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t ino, blkmap_t *blkmap,
 			break;
 		}
 		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, bno),
-				XFS_FSB_TO_BB(mp, 1), 0, NULL);
+				    XFS_FSB_TO_BB(mp, 1), 0,
+				    &xfs_attr3_rmt_buf_ops);
 		if (!bp) {
 			do_warn(
 	_("can't read remote block for attributes of inode %" PRIu64 "\n"), ino);
 			clearit = 1;
 			break;
 		}
+
+		if (bp->b_error == EFSBADCRC || bp->b_error == EFSCORRUPTED) {
+			do_warn(
+	_("Corrupt remote block for attributes of inode %" PRIu64 "\n"), ino);
+			clearit = 1;
+			break;
+		}
+
 		ASSERT(mp->m_sb.sb_blocksize == XFS_BUF_COUNT(bp));
-		length = MIN(XFS_BUF_COUNT(bp), valuelen - amountdone);
-		memmove(value, XFS_BUF_PTR(bp), length);
+
+		length = MIN(XFS_BUF_COUNT(bp) - hdrsize, valuelen - amountdone);
+		memmove(value, XFS_BUF_PTR(bp) + hdrsize, length);
 		amountdone += length;
 		value += length;
 		i++;
@@ -1320,13 +1336,16 @@ process_leaf_attr_level(xfs_mount_t	*mp,
 		}
 
 		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, dev_bno),
-					XFS_FSB_TO_BB(mp, 1), 0, NULL);
+				    XFS_FSB_TO_BB(mp, 1), 0,
+				    &xfs_attr3_leaf_buf_ops);
 		if (!bp) {
 			do_warn(
 	_("can't read file block %u (fsbno %" PRIu64 ") for attribute fork of inode %" PRIu64 "\n"),
 				da_bno, dev_bno, ino);
 			goto error_out;
 		}
+		if (bp->b_error == EFSBADCRC)
+			repair++;
 
 		leaf = bp->b_addr;
 		xfs_attr3_leaf_hdr_from_disk(&leafhdr, leaf);
@@ -1382,9 +1401,9 @@ process_leaf_attr_level(xfs_mount_t	*mp,
 
 		current_hashval = greatest_hashval;
 
-		if (repair && !no_modify) 
+		if (repair && !no_modify)
 			libxfs_writebuf(bp, 0);
-		else 
+		else
 			libxfs_putbuf(bp);
 	} while (da_bno != 0);
 
@@ -1512,6 +1531,8 @@ process_longform_attr(
 			ino);
 		return(1);
 	}
+	if (bp->b_error == EFSBADCRC)
+		(*repair)++;
 
 	/* verify leaf block */
 	leaf = (xfs_attr_leafblock_t *)XFS_BUF_PTR(bp);
@@ -1555,7 +1576,7 @@ process_longform_attr(
 	case XFS_DA_NODE_MAGIC:		/* btree-form attribute */
 	case XFS_DA3_NODE_MAGIC:
 		/* must do this now, to release block 0 before the traversal */
-		if (repairlinks) {
+		if (*repair || repairlinks) {
 			*repair = 1;
 			libxfs_writebuf(bp, 0);
 		} else
-- 
1.9.0

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Re: [PATCH 9/9] repair: detect and handle attribute tree CRC errors

[Brian Foster]

On Tue, Apr 15, 2014 at 06:25:01PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> Currently the attribute code will not detect and correct errors in
> the attribute tree. It also fails to validate the CRCs and headers
> on remote attribute blocks. Ensure that all the attribute blocks are
> CRC checked and that the processing functions understand the correct
> block formats for decoding.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  repair/attr_repair.c | 35 ++++++++++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/repair/attr_repair.c b/repair/attr_repair.c
> index ba85ac2..13ec90e 100644
> --- a/repair/attr_repair.c
> +++ b/repair/attr_repair.c
> @@ -611,6 +611,8 @@ verify_da_path(xfs_mount_t	*mp,
>  		ASSERT(cursor->level[this_level].dirty == 0 ||
>  			(cursor->level[this_level].dirty && !no_modify));
>  
> +		if (bp->b_error == EFSBADCRC)
> +			cursor->level[this_level].dirty++;

I was wondering why this wasn't checked closer to the readbuf call, then
I noticed the assert. Any reason not to be consistent with the other
changes, move this up closer to the call and nuke the assert?

>  		if (cursor->level[this_level].dirty && !no_modify)
>  			libxfs_writebuf(cursor->level[this_level].bp, 0);
>  		else
> @@ -974,6 +976,10 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t ino, blkmap_t *blkmap,
>  	xfs_dfsbno_t	bno;
>  	xfs_buf_t	*bp;
>  	int		clearit = 0, i = 0, length = 0, amountdone = 0;
> +	int		hdrsize = 0;
> +
> +	if (xfs_sb_version_hascrc(&mp->m_sb))
> +		hdrsize = sizeof(struct xfs_attr3_rmt_hdr);
>  
>  	/* ASSUMPTION: valuelen is a valid number, so use it for looping */
>  	/* Note that valuelen is not a multiple of blocksize */
> @@ -986,16 +992,26 @@ rmtval_get(xfs_mount_t *mp, xfs_ino_t ino, blkmap_t *blkmap,
>  			break;
>  		}
>  		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, bno),
> -				XFS_FSB_TO_BB(mp, 1), 0, NULL);
> +				    XFS_FSB_TO_BB(mp, 1), 0,
> +				    &xfs_attr3_rmt_buf_ops);
>  		if (!bp) {
>  			do_warn(
>  	_("can't read remote block for attributes of inode %" PRIu64 "\n"), ino);
>  			clearit = 1;
>  			break;
>  		}
> +
> +		if (bp->b_error == EFSBADCRC || bp->b_error == EFSCORRUPTED) {
> +			do_warn(
> +	_("Corrupt remote block for attributes of inode %" PRIu64 "\n"), ino);
> +			clearit = 1;
> +			break;
> +		}
> +
>  		ASSERT(mp->m_sb.sb_blocksize == XFS_BUF_COUNT(bp));
> -		length = MIN(XFS_BUF_COUNT(bp), valuelen - amountdone);
> -		memmove(value, XFS_BUF_PTR(bp), length);
> +
> +		length = MIN(XFS_BUF_COUNT(bp) - hdrsize, valuelen - amountdone);
> +		memmove(value, XFS_BUF_PTR(bp) + hdrsize, length);
>  		amountdone += length;
>  		value += length;
>  		i++;
> @@ -1320,13 +1336,16 @@ process_leaf_attr_level(xfs_mount_t	*mp,
>  		}
>  
>  		bp = libxfs_readbuf(mp->m_dev, XFS_FSB_TO_DADDR(mp, dev_bno),
> -					XFS_FSB_TO_BB(mp, 1), 0, NULL);
> +				    XFS_FSB_TO_BB(mp, 1), 0,
> +				    &xfs_attr3_leaf_buf_ops);
>  		if (!bp) {
>  			do_warn(
>  	_("can't read file block %u (fsbno %" PRIu64 ") for attribute fork of inode %" PRIu64 "\n"),
>  				da_bno, dev_bno, ino);
>  			goto error_out;
>  		}
> +		if (bp->b_error == EFSBADCRC)
> +			repair++;

Could you remind me why we only check EFSBADCRC in some places and
EFSCORRUPTED as well in others?

>  
>  		leaf = bp->b_addr;
>  		xfs_attr3_leaf_hdr_from_disk(&leafhdr, leaf);
> @@ -1382,9 +1401,9 @@ process_leaf_attr_level(xfs_mount_t	*mp,
>  
>  		current_hashval = greatest_hashval;
>  
> -		if (repair && !no_modify) 
> +		if (repair && !no_modify)
>  			libxfs_writebuf(bp, 0);
> -		else 
> +		else
>  			libxfs_putbuf(bp);
>  	} while (da_bno != 0);
>  
> @@ -1512,6 +1531,8 @@ process_longform_attr(
>  			ino);
>  		return(1);
>  	}
> +	if (bp->b_error == EFSBADCRC)
> +		(*repair)++;

Note that repair is unconditionally reset to 0 at the beginning of
process_leaf_attr_block() (in the XFS_ATTR_LEAF_MAGIC case further down
this function).

Brian

>  
>  	/* verify leaf block */
>  	leaf = (xfs_attr_leafblock_t *)XFS_BUF_PTR(bp);
> @@ -1555,7 +1576,7 @@ process_longform_attr(
>  	case XFS_DA_NODE_MAGIC:		/* btree-form attribute */
>  	case XFS_DA3_NODE_MAGIC:
>  		/* must do this now, to release block 0 before the traversal */
> -		if (repairlinks) {
> +		if (*repair || repairlinks) {
>  			*repair = 1;
>  			libxfs_writebuf(bp, 0);
>  		} else
> -- 
> 1.9.0
> 
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> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH 9/9] repair: detect and handle attribute tree CRC errors

[Dave Chinner]

On Wed, Apr 16, 2014 at 09:25:04AM -0400, Brian Foster wrote:
> On Tue, Apr 15, 2014 at 06:25:01PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > Currently the attribute code will not detect and correct errors in
> > the attribute tree. It also fails to validate the CRCs and headers
> > on remote attribute blocks. Ensure that all the attribute blocks are
> > CRC checked and that the processing functions understand the correct
> > block formats for decoding.
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > ---
> >  repair/attr_repair.c | 35 ++++++++++++++++++++++++++++-------
> >  1 file changed, 28 insertions(+), 7 deletions(-)
> > 
> > diff --git a/repair/attr_repair.c b/repair/attr_repair.c
> > index ba85ac2..13ec90e 100644
> > --- a/repair/attr_repair.c
> > +++ b/repair/attr_repair.c
> > @@ -611,6 +611,8 @@ verify_da_path(xfs_mount_t	*mp,
> >  		ASSERT(cursor->level[this_level].dirty == 0 ||
> >  			(cursor->level[this_level].dirty && !no_modify));
> >  
> > +		if (bp->b_error == EFSBADCRC)
> > +			cursor->level[this_level].dirty++;
> 
> I was wondering why this wasn't checked closer to the readbuf call, then
> I noticed the assert. Any reason not to be consistent with the other
> changes, move this up closer to the call and nuke the assert?

Because I didn't want to modify the cursor state if the buffer
failed the basic checks (i.e. if (bad) {... return} branch was
taken) as if it is bad we aren't even going to try to repair it.
Hence marking it dirty for writeout when it might not even be an
attr block is probably a bad thing...

> >  		if (!bp) {
> >  			do_warn(
> >  	_("can't read file block %u (fsbno %" PRIu64 ") for attribute fork of inode %" PRIu64 "\n"),
> >  				da_bno, dev_bno, ino);
> >  			goto error_out;
> >  		}
> > +		if (bp->b_error == EFSBADCRC)
> > +			repair++;
> 
> Could you remind me why we only check EFSBADCRC in some places and
> EFSCORRUPTED as well in others?

Here we are checking and repairing the buffer, so EFSCORRUPTED
detection doesn't provide any value - if there is a corruption,
repair will already handle it and fix it. Hence this is here to
catch a buffer with a bad CRC but is otherwise good (e.g. bit error
in usused/unreferenced space in the metadata block).

> 
> >  
> >  		leaf = bp->b_addr;
> >  		xfs_attr3_leaf_hdr_from_disk(&leafhdr, leaf);
> > @@ -1382,9 +1401,9 @@ process_leaf_attr_level(xfs_mount_t	*mp,
> >  
> >  		current_hashval = greatest_hashval;
> >  
> > -		if (repair && !no_modify) 
> > +		if (repair && !no_modify)
> >  			libxfs_writebuf(bp, 0);
> > -		else 
> > +		else
> >  			libxfs_putbuf(bp);
> >  	} while (da_bno != 0);
> >  
> > @@ -1512,6 +1531,8 @@ process_longform_attr(
> >  			ino);
> >  		return(1);
> >  	}
> > +	if (bp->b_error == EFSBADCRC)
> > +		(*repair)++;
> 
> Note that repair is unconditionally reset to 0 at the beginning of
> process_leaf_attr_block() (in the XFS_ATTR_LEAF_MAGIC case further down
> this function).

Oh, so it is. I missed that. Good catch! Will fix.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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