[PATCH 04/22] xfs: add CRC checks to the AGFL

Dave Chinner
2013-04-03T05:11:53Z

From: Christoph Hellwig <hch@lst.de>

Add CRC checks, location information and a magic number to the AGFL.
Previously the AGFL was just a block containing nothing but the
free block pointers. The new AGFL has a real header with the usual
boilerplate instead, so that we can verify it's not corrupted and
written into the right place.

[dchinner@redhat.com] Added LSN field, reworked significantly to fit
into new verifier structure and growfs structure, enabled full
verifier functionality now there is a header to verify and we can
guarantee an initialised AGFL.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_ag.h | 25 +++++++++-
fs/xfs/xfs_alloc.c | 119 ++++++++++++++++++++++++++++++----------------
fs/xfs/xfs_buf_item.h | 4 +-
fs/xfs/xfs_fsops.c | 5 ++
fs/xfs/xfs_log_recover.c | 10 ++++
5 files changed, 119 insertions(+), 44 deletions(-)

diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
index 9f4815e..272ef09 100644
--- a/fs/xfs/xfs_ag.h
+++ b/fs/xfs/xfs_ag.h
@@ -30,6 +30,7 @@ struct xfs_trans;

#define XFS_AGF_MAGIC 0x58414746 /* 'XAGF' */
#define XFS_AGI_MAGIC 0x58414749 /* 'XAGI' */
+#define XFS_AGFL_MAGIC 0x5841464c /* 'XAFL' */
#define XFS_AGF_VERSION 1
#define XFS_AGI_VERSION 1

@@ -190,11 +191,31 @@ extern const struct xfs_buf_ops xfs_agi_buf_ops;
*/
#define XFS_AGFL_DADDR(mp) ((xfs_daddr_t)(3 << (mp)->m_sectbb_log))
#define XFS_AGFL_BLOCK(mp) XFS_HDR_BLOCK(mp, XFS_AGFL_DADDR(mp))
-#define XFS_AGFL_SIZE(mp) ((mp)->m_sb.sb_sectsize / sizeof(xfs_agblock_t))
#define XFS_BUF_TO_AGFL(bp) ((xfs_agfl_t *)((bp)->b_addr))

+#define XFS_BUF_TO_AGFL_BNO(mp, bp) \
+ (xfs_sb_version_hascrc(&((mp)->m_sb)) ? \
+ &(XFS_BUF_TO_AGFL(bp)->agfl_bno[0]) : \
+ (__be32 *)(bp)->b_addr)
+
+/*
+ * Size of the AGFL. For CRC-enabled filesystes we steal a couple of
+ * slots in the beginning of the block for a proper header with the
+ * location information and CRC.
+ */
+#define XFS_AGFL_SIZE(mp) \
+ (((mp)->m_sb.sb_sectsize - \
+ (xfs_sb_version_hascrc(&((mp)->m_sb)) ? \
+ sizeof(struct xfs_agfl) : 0)) / \
+ sizeof(xfs_agblock_t))
+
typedef struct xfs_agfl {
- __be32 agfl_bno[1]; /* actually XFS_AGFL_SIZE(mp) */
+ __be32 agfl_magicnum;
+ __be32 agfl_seqno;
+ uuid_t agfl_uuid;
+ __be64 agfl_lsn;
+ __be32 agfl_crc;
+ __be32 agfl_bno[]; /* actually XFS_AGFL_SIZE(mp) */
} xfs_agfl_t;

/*
diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index c34f799..40d3d57 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -432,53 +432,84 @@ xfs_alloc_fixup_trees(
return 0;
}

-static void
+static bool
xfs_agfl_verify(
struct xfs_buf *bp)
{
-#ifdef WHEN_CRCS_COME_ALONG
- /*
- * we cannot actually do any verification of the AGFL because mkfs does
- * not initialise the AGFL to zero or NULL. Hence the only valid part of
- * the AGFL is what the AGF says is active. We can't get to the AGF, so
- * we can't verify just those entries are valid.
- *
- * This problem goes away when the CRC format change comes along as that
- * requires the AGFL to be initialised by mkfs. At that point, we can
- * verify the blocks in the agfl -active or not- lie within the bounds
- * of the AG. Until then, just leave this check ifdef'd out.
- */
struct xfs_mount *mp = bp->b_target->bt_mount;
struct xfs_agfl *agfl = XFS_BUF_TO_AGFL(bp);
- int agfl_ok = 1;
-
int i;

+ if (!uuid_equal(&agfl->agfl_uuid, &mp->m_sb.sb_uuid))
+ return false;
+ if (be32_to_cpu(agfl->agfl_magicnum) != XFS_AGFL_MAGIC)
+ return false;
+ /*
+ * during growfs operations, the perag is not fully initialised,
+ * so we can't use it for any useful checking. growfs ensures we can't
+ * use it by using uncached buffers that don't have the perag attached
+ * so we can detect and avoid this problem.
+ */
+ if (bp->b_pag && be32_to_cpu(agfl->agfl_seqno) != bp->b_pag->pag_agno)
+ return false;
+
for (i = 0; i < XFS_AGFL_SIZE(mp); i++) {
- if (be32_to_cpu(agfl->agfl_bno[i]) == NULLAGBLOCK ||
+ if (be32_to_cpu(agfl->agfl_bno[i]) != NULLAGBLOCK &&
be32_to_cpu(agfl->agfl_bno[i]) >= mp->m_sb.sb_agblocks)
- agfl_ok = 0;
+ return false;
}
+ return true;
+}
+
+static void
+xfs_agfl_read_verify(
+ struct xfs_buf *bp)
+{
+ struct xfs_mount *mp = bp->b_target->bt_mount;
+ int agfl_ok = 1;
+
+ /*
+ * There is no verification of non-crc AGFLs because mkfs does not
+ * initialise the AGFL to zero or NULL. Hence the only valid part of the
+ * AGFL is what the AGF says is active. We can't get to the AGF, so we
+ * can't verify just those entries are valid.
+ */
+ if (!xfs_sb_version_hascrc(&mp->m_sb))
+ return;
+
+ agfl_ok = xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
+ offsetof(struct xfs_agfl, agfl_crc));
+
+ agfl_ok = agfl_ok && xfs_agfl_verify(bp);

if (!agfl_ok) {
- XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, agfl);
+ XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
xfs_buf_ioerror(bp, EFSCORRUPTED);
}
-#endif
}

static void
xfs_agfl_write_verify(
struct xfs_buf *bp)
{
- xfs_agfl_verify(bp);
-}
+ struct xfs_mount *mp = bp->b_target->bt_mount;
+ struct xfs_buf_log_item *bip = bp->b_fspriv;

-static void
-xfs_agfl_read_verify(
- struct xfs_buf *bp)
-{
- xfs_agfl_verify(bp);
+ /* no verification of non-crc AGFLs */
+ if (!xfs_sb_version_hascrc(&mp->m_sb))
+ return;
+
+ if (!xfs_agfl_verify(bp)) {
+ XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
+ xfs_buf_ioerror(bp, EFSCORRUPTED);
+ return;
+ }
+
+ if (bip)
+ XFS_BUF_TO_AGFL(bp)->agfl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
+
+ xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
+ offsetof(struct xfs_agfl, agfl_crc));
}

const struct xfs_buf_ops xfs_agfl_buf_ops = {
@@ -1984,18 +2015,18 @@ xfs_alloc_get_freelist(
int btreeblk) /* destination is a AGF btree */
{
xfs_agf_t *agf; /* a.g. freespace structure */
- xfs_agfl_t *agfl; /* a.g. freelist structure */
xfs_buf_t *agflbp;/* buffer for a.g. freelist structure */
xfs_agblock_t bno; /* block number returned */
+ __be32 *agfl_bno;
int error;
int logflags;
- xfs_mount_t *mp; /* mount structure */
+ xfs_mount_t *mp = tp->t_mountp;
xfs_perag_t *pag; /* per allocation group data */

- agf = XFS_BUF_TO_AGF(agbp);
/*
* Freelist is empty, give up.
*/
+ agf = XFS_BUF_TO_AGF(agbp);
if (!agf->agf_flcount) {
*bnop = NULLAGBLOCK;
return 0;
@@ -2003,15 +2034,17 @@ xfs_alloc_get_freelist(
/*
* Read the array of free blocks.
*/
- mp = tp->t_mountp;
- if ((error = xfs_alloc_read_agfl(mp, tp,
- be32_to_cpu(agf->agf_seqno), &agflbp)))
+ error = xfs_alloc_read_agfl(mp, tp, be32_to_cpu(agf->agf_seqno),
+ &agflbp);
+ if (error)
return error;
- agfl = XFS_BUF_TO_AGFL(agflbp);
+
+
/*
* Get the block number and update the data structures.
*/
- bno = be32_to_cpu(agfl->agfl_bno[be32_to_cpu(agf->agf_flfirst)]);
+ agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agflbp);
+ bno = be32_to_cpu(agfl_bno[be32_to_cpu(agf->agf_flfirst)]);
be32_add_cpu(&agf->agf_flfirst, 1);
xfs_trans_brelse(tp, agflbp);
if (be32_to_cpu(agf->agf_flfirst) == XFS_AGFL_SIZE(mp))
@@ -2104,12 +2137,13 @@ xfs_alloc_put_freelist(
int btreeblk) /* block came from a AGF btree */
{
xfs_agf_t *agf; /* a.g. freespace structure */
- xfs_agfl_t *agfl; /* a.g. free block array */
__be32 *blockp;/* pointer to array entry */
int error;
int logflags;
xfs_mount_t *mp; /* mount structure */
xfs_perag_t *pag; /* per allocation group data */
+ __be32 *agfl_bno;
+ int startoff;

agf = XFS_BUF_TO_AGF(agbp);
mp = tp->t_mountp;
@@ -2117,7 +2151,6 @@ xfs_alloc_put_freelist(
if (!agflbp && (error = xfs_alloc_read_agfl(mp, tp,
be32_to_cpu(agf->agf_seqno), &agflbp)))
return error;
- agfl = XFS_BUF_TO_AGFL(agflbp);
be32_add_cpu(&agf->agf_fllast, 1);
if (be32_to_cpu(agf->agf_fllast) == XFS_AGFL_SIZE(mp))
agf->agf_fllast = 0;
@@ -2138,13 +2171,17 @@ xfs_alloc_put_freelist(
xfs_alloc_log_agf(tp, agbp, logflags);

ASSERT(be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp));
- blockp = &agfl->agfl_bno[be32_to_cpu(agf->agf_fllast)];
+
+ agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agflbp);
+ blockp = &agfl_bno[be32_to_cpu(agf->agf_fllast)];
*blockp = cpu_to_be32(bno);
+ startoff = (char *)blockp - (char *)agflbp->b_addr;
+
xfs_alloc_log_agf(tp, agbp, logflags);
- xfs_trans_log_buf(tp, agflbp,
- (int)((xfs_caddr_t)blockp - (xfs_caddr_t)agfl),
- (int)((xfs_caddr_t)blockp - (xfs_caddr_t)agfl +
- sizeof(xfs_agblock_t) - 1));
+
+ xfs_trans_buf_set_type(tp, agflbp, XFS_BLF_AGFL_BUF);
+ xfs_trans_log_buf(tp, agflbp, startoff,
+ startoff + sizeof(xfs_agblock_t) - 1);
return 0;
}

diff --git a/fs/xfs/xfs_buf_item.h b/fs/xfs/xfs_buf_item.h
index 76bd7a1..067d5f0 100644
--- a/fs/xfs/xfs_buf_item.h
+++ b/fs/xfs/xfs_buf_item.h
@@ -46,13 +46,15 @@ extern kmem_zone_t *xfs_buf_item_zone;
*/
#define XFS_BLF_BTREE_BUF (1<<5)
#define XFS_BLF_AGF_BUF (1<<6)
+#define XFS_BLF_AGFL_BUF (1<<7)

#define XFS_BLF_TYPE_MASK \
(XFS_BLF_UDQUOT_BUF | \
XFS_BLF_PDQUOT_BUF | \
XFS_BLF_GDQUOT_BUF | \
XFS_BLF_BTREE_BUF | \
- XFS_BLF_AGF_BUF)
+ XFS_BLF_AGF_BUF | \
+ XFS_BLF_AGFL_BUF)

#define XFS_BLF_CHUNK 128
#define XFS_BLF_SHIFT 7
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index b6cca27..a693a54 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -268,6 +268,11 @@ xfs_growfs_data_private(
}

agfl = XFS_BUF_TO_AGFL(bp);
+ if (xfs_sb_version_hascrc(&mp->m_sb)) {
+ agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
+ agfl->agfl_seqno = cpu_to_be32(agno);
+ uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_uuid);
+ }
for (bucket = 0; bucket < XFS_AGFL_SIZE(mp); bucket++)
agfl->agfl_bno[bucket] = cpu_to_be32(NULLAGBLOCK);

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index dadf245..da2a19e 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1961,6 +1961,16 @@ xlog_recover_do_reg_buffer(
}
bp->b_ops = &xfs_agf_buf_ops;
break;
+ case XFS_BLF_AGFL_BUF:
+ if (!xfs_sb_version_hascrc(&mp->m_sb))
+ break;
+ if (*(__be32 *)bp->b_addr != cpu_to_be32(XFS_AGFL_MAGIC)) {
+ xfs_warn(mp, "Bad AGFL block magic!");
+ ASSERT(0);
+ break;
+ }
+ bp->b_ops = &xfs_agfl_buf_ops;
+ break;
default:
break;
}
--
1.7.10.4