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-rw-r--r--fs/xfs/libxfs/xfs_alloc.c94
-rw-r--r--fs/xfs/xfs_mount.h1
-rw-r--r--fs/xfs/xfs_trace.h9
3 files changed, 103 insertions, 1 deletions
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 3db90b707fb2..39387bdd225d 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2063,6 +2063,93 @@ xfs_alloc_space_available(
}
/*
+ * Check the agfl fields of the agf for inconsistency or corruption. The purpose
+ * is to detect an agfl header padding mismatch between current and early v5
+ * kernels. This problem manifests as a 1-slot size difference between the
+ * on-disk flcount and the active [first, last] range of a wrapped agfl. This
+ * may also catch variants of agfl count corruption unrelated to padding. Either
+ * way, we'll reset the agfl and warn the user.
+ *
+ * Return true if a reset is required before the agfl can be used, false
+ * otherwise.
+ */
+static bool
+xfs_agfl_needs_reset(
+ struct xfs_mount *mp,
+ struct xfs_agf *agf)
+{
+ uint32_t f = be32_to_cpu(agf->agf_flfirst);
+ uint32_t l = be32_to_cpu(agf->agf_fllast);
+ uint32_t c = be32_to_cpu(agf->agf_flcount);
+ int agfl_size = xfs_agfl_size(mp);
+ int active;
+
+ /* no agfl header on v4 supers */
+ if (!xfs_sb_version_hascrc(&mp->m_sb))
+ return false;
+
+ /*
+ * The agf read verifier catches severe corruption of these fields.
+ * Repeat some sanity checks to cover a packed -> unpacked mismatch if
+ * the verifier allows it.
+ */
+ if (f >= agfl_size || l >= agfl_size)
+ return true;
+ if (c > agfl_size)
+ return true;
+
+ /*
+ * Check consistency between the on-disk count and the active range. An
+ * agfl padding mismatch manifests as an inconsistent flcount.
+ */
+ if (c && l >= f)
+ active = l - f + 1;
+ else if (c)
+ active = agfl_size - f + l + 1;
+ else
+ active = 0;
+
+ return active != c;
+}
+
+/*
+ * Reset the agfl to an empty state. Ignore/drop any existing blocks since the
+ * agfl content cannot be trusted. Warn the user that a repair is required to
+ * recover leaked blocks.
+ *
+ * The purpose of this mechanism is to handle filesystems affected by the agfl
+ * header padding mismatch problem. A reset keeps the filesystem online with a
+ * relatively minor free space accounting inconsistency rather than suffer the
+ * inevitable crash from use of an invalid agfl block.
+ */
+static void
+xfs_agfl_reset(
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp,
+ struct xfs_perag *pag)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_agf *agf = XFS_BUF_TO_AGF(agbp);
+
+ ASSERT(pag->pagf_agflreset);
+ trace_xfs_agfl_reset(mp, agf, 0, _RET_IP_);
+
+ xfs_warn(mp,
+ "WARNING: Reset corrupted AGFL on AG %u. %d blocks leaked. "
+ "Please unmount and run xfs_repair.",
+ pag->pag_agno, pag->pagf_flcount);
+
+ agf->agf_flfirst = 0;
+ agf->agf_fllast = cpu_to_be32(xfs_agfl_size(mp) - 1);
+ agf->agf_flcount = 0;
+ xfs_alloc_log_agf(tp, agbp, XFS_AGF_FLFIRST | XFS_AGF_FLLAST |
+ XFS_AGF_FLCOUNT);
+
+ pag->pagf_flcount = 0;
+ pag->pagf_agflreset = false;
+}
+
+/*
* Decide whether to use this allocation group for this allocation.
* If so, fix up the btree freelist's size.
*/
@@ -2123,6 +2210,10 @@ xfs_alloc_fix_freelist(
}
}
+ /* reset a padding mismatched agfl before final free space check */
+ if (pag->pagf_agflreset)
+ xfs_agfl_reset(tp, agbp, pag);
+
/* If there isn't enough total space or single-extent, reject it. */
need = xfs_alloc_min_freelist(mp, pag);
if (!xfs_alloc_space_available(args, need, flags))
@@ -2279,6 +2370,7 @@ xfs_alloc_get_freelist(
agf->agf_flfirst = 0;
pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno));
+ ASSERT(!pag->pagf_agflreset);
be32_add_cpu(&agf->agf_flcount, -1);
xfs_trans_agflist_delta(tp, -1);
pag->pagf_flcount--;
@@ -2390,6 +2482,7 @@ xfs_alloc_put_freelist(
agf->agf_fllast = 0;
pag = xfs_perag_get(mp, be32_to_cpu(agf->agf_seqno));
+ ASSERT(!pag->pagf_agflreset);
be32_add_cpu(&agf->agf_flcount, 1);
xfs_trans_agflist_delta(tp, 1);
pag->pagf_flcount++;
@@ -2597,6 +2690,7 @@ xfs_alloc_read_agf(
pag->pagb_count = 0;
pag->pagb_tree = RB_ROOT;
pag->pagf_init = 1;
+ pag->pagf_agflreset = xfs_agfl_needs_reset(mp, agf);
}
#ifdef DEBUG
else if (!XFS_FORCED_SHUTDOWN(mp)) {
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 1808f56decaa..10b90bbc5162 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -353,6 +353,7 @@ typedef struct xfs_perag {
char pagi_inodeok; /* The agi is ok for inodes */
uint8_t pagf_levels[XFS_BTNUM_AGF];
/* # of levels in bno & cnt btree */
+ bool pagf_agflreset; /* agfl requires reset before use */
uint32_t pagf_flcount; /* count of blocks in freelist */
xfs_extlen_t pagf_freeblks; /* total free blocks */
xfs_extlen_t pagf_longest; /* longest free space */
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 945de08af7ba..a982c0b623d0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1477,7 +1477,7 @@ TRACE_EVENT(xfs_extent_busy_trim,
__entry->tlen)
);
-TRACE_EVENT(xfs_agf,
+DECLARE_EVENT_CLASS(xfs_agf_class,
TP_PROTO(struct xfs_mount *mp, struct xfs_agf *agf, int flags,
unsigned long caller_ip),
TP_ARGS(mp, agf, flags, caller_ip),
@@ -1533,6 +1533,13 @@ TRACE_EVENT(xfs_agf,
__entry->longest,
(void *)__entry->caller_ip)
);
+#define DEFINE_AGF_EVENT(name) \
+DEFINE_EVENT(xfs_agf_class, name, \
+ TP_PROTO(struct xfs_mount *mp, struct xfs_agf *agf, int flags, \
+ unsigned long caller_ip), \
+ TP_ARGS(mp, agf, flags, caller_ip))
+DEFINE_AGF_EVENT(xfs_agf);
+DEFINE_AGF_EVENT(xfs_agfl_reset);
TRACE_EVENT(xfs_free_extent,
TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agblock_t agbno,