From: Dave Chinner <dchinner@xxxxxxxxxx>
Now that we can safely detect whether we have a screwed up AGFL
size, we need to automatically fix it up. We do this by modifying
the AGFL index and/or count values in the AGF. This will only ever
lead to reducing the size of the AGFL, leaving a free block in the
unused slot to remain there if a problem is corrected. WHile this is
a leak, it should only occur once and it will be corrected the next
time the filesystem is repaired.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_alloc.c | 105 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 99 insertions(+), 6 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 31a18fe..8deb736 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2417,10 +2417,7 @@ xfs_agf_verify(
if (!(agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
- be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) &&
- be32_to_cpu(agf->agf_flfirst) < agfl_size &&
- be32_to_cpu(agf->agf_fllast) < agfl_size &&
- be32_to_cpu(agf->agf_flcount) <= agfl_size))
+ be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length)))
return false;
if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) > XFS_BTREE_MAXLEVELS ||
@@ -2440,10 +2437,18 @@ xfs_agf_verify(
be32_to_cpu(agf->agf_btreeblks) > be32_to_cpu(agf->agf_length))
return false;
- if (!xfs_sb_version_hascrc(&mp->m_sb))
+ /*
+ * AGFL parameters are strict only for non-CRC filesystems now.
+ * See the comment below in the v5 format section for details
+ */
+ if (!xfs_sb_version_hascrc(&mp->m_sb)) {
+ if (!(flfirst < agfl_size && fllast < agfl_size &&
+ flcount <= agfl_size))
+ return false;
return true;
+ }
- /* CRC format checks only from here */
+ /* v5 format checks only from here */
if (!uuid_equal(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid))
return false;
@@ -2575,6 +2580,92 @@ xfs_read_agf(
}
/*
+ * Detect and fixup a screwup in the struct xfs_agfl definition that results in
+ * different free list sizes depending on the compiler padding added to the
+ * xfs_agfl. This will only matter on v5 filesystems that have the freelist
+ * wrapping around the end of the AGFL. The changes fixup changes will be logged
+ * in the first free list modification done to the AGF.
+ */
+static void
+xfs_agf_fixup_freelist_count(
+ struct xfs_mount *mp,
+ struct xfs_perag *pag,
+ struct xfs_agf *agf)
+{
+ int32_t agfl_size = xfs_agfl_size(mp);
+ int32_t active;
+
+ ASSERT(pag->pagf_fllast <= agfl_size);
+ ASSERT(pag->pagf_flfirst <= agfl_size);
+
+ if (!xfs_sb_version_hascrc(&mp->m_sb))
+ return;
+
+ /* if not wrapped or completely within range, nothing to do */
+ if (pag->pagf_fllast < agfl_size &&
+ pag->pagf_flfirst <= pag->pagf_fllast)
+ return;
+
+ /* if last is invalid, pull it back and return */
+ if (pag->pagf_fllast == agfl_size) {
+ xfs_notice(mp, "AGF %d: last index fixup being performed",
+ pag->pag_agno);
+ if (pag->pagf_flcount) {
+ pag->pagf_flcount--;
+ be32_add_cpu(&agf->agf_flcount, -1);
+ be32_add_cpu(&agf->agf_fllast, -1);
+ pag->pagf_fllast--;
+ } else {
+ /* empty free list, move the both pointers back one */
+ ASSERT(pag->pagf_flfirst == pag->pagf_fllast);
+ be32_add_cpu(&agf->agf_fllast, -1);
+ be32_add_cpu(&agf->agf_flfirst, -1);
+ pag->pagf_flfirst--;
+ pag->pagf_fllast--;
+ }
+ return;
+ }
+
+ /* if first is invalid, wrap it, reset count and return */
+ if (pag->pagf_flfirst == agfl_size) {
+ xfs_notice(mp, "AGF %d: first index fixup being performed",
+ pag->pag_agno);
+ ASSERT(pag->pagf_flfirst != pag->pagf_fllast);
+ ASSERT(pag->pagf_flcount);
+ pag->pagf_flcount = pag->pagf_fllast + 1;
+ agf->agf_flcount = cpu_to_be32(pag->pagf_flcount);
+ agf->agf_flfirst = 0;
+ pag->pagf_flfirst = 0;
+ return;
+ }
+
+ /*
+ * Pure wrap, first and last are valid.
+ * flfirst
+ * |
+ * +oo------------------oo+
+ * |
+ * fllast
+ *
+ * We need to determine if the count includes the last slot in the AGFL
+ * which we no longer use. If the flcount does not match the expected
+ * size based on the first/last indexes, we need to fix it up.
+ */
+ active = pag->pagf_fllast - pag->pagf_flfirst + 1;
+ if (active <= 0)
+ active += agfl_size;
+ if (active == pag->pagf_flcount)
+ return;
+
+ /* should only be off by one */
+ ASSERT(active + 1 == pag->pagf_flcount);
+ xfs_notice(mp, "AGF %d: wrapped count fixup being performed",
+ pag->pag_agno);
+ pag->pagf_flcount--;
+ be32_add_cpu(&agf->agf_flcount, -1);
+}
+
+/*
* Read in the allocation group header (free/alloc section).
*/
int /* error */
@@ -2620,6 +2711,8 @@ xfs_alloc_read_agf(
pag->pagb_count = 0;
pag->pagb_tree = RB_ROOT;
pag->pagf_init = 1;
+
+ xfs_agf_fixup_freelist_count(mp, pag, agf);
}
#ifdef DEBUG
else if (!XFS_FORCED_SHUTDOWN(mp)) {
--
2.8.0.rc3
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