[PATCH v6 13/18] xfs: allocate sparse inode chunks on full chunk allocation failure

Brian Foster
2015-03-02T13:28:12Z

xfs_ialloc_ag_alloc() makes several attempts to allocate a full inode
chunk. If all else fails, reduce the allocation to the sparse length and
alignment and attempt to allocate a sparse inode chunk.

If sparse chunk allocation succeeds, check whether an inobt record
already exists that can track the chunk. If so, inherit and update the
existing record. Otherwise, insert a new record for the sparse chunk.

Create helpers to align sparse chunk inode records and insert or update
existing records in the inode btrees. The xfs_inobt_insert_sprec()
helper implements the merge or update semantics required for sparse
inode records with respect to both the inobt and finobt. To update the
inobt, either insert a new record or merge with an existing record. To
update the finobt, use the updated inobt record to either insert or
replace an existing record.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
fs/xfs/libxfs/xfs_ialloc.c | 330 +++++++++++++++++++++++++++++++++++++--
fs/xfs/libxfs/xfs_ialloc_btree.c | 31 ++++
fs/xfs/libxfs/xfs_ialloc_btree.h | 7 +
fs/xfs/xfs_trace.h | 47 ++++++
4 files changed, 401 insertions(+), 14 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index d79e41c..90594b8 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -378,6 +378,214 @@ xfs_ialloc_inode_init(
}

/*
+ * Align startino and allocmask for a recently allocated sparse chunk such that
+ * they are fit for insertion (or merge) into the on-disk inode btrees.
+ *
+ * Background:
+ *
+ * When enabled, sparse inode support increases the inode alignment from cluster
+ * size to inode chunk size. This means that the minimum range between two
+ * non-adjacent inode records in the inobt is large enough for a full inode
+ * record. This allows for cluster sized, cluster aligned block allocation
+ * without need to worry about whether the resulting inode record overlaps with
+ * another record in the tree. Without this basic rule, we would have to deal
+ * with the consequences of overlap by potentially undoing recent allocations in
+ * the inode allocation codepath.
+ *
+ * Because of this alignment rule (which is enforced on mount), there are two
+ * inobt possibilities for newly allocated sparse chunks. One is that the
+ * aligned inode record for the chunk covers a range of inodes not already
+ * covered in the inobt (i.e., it is safe to insert a new sparse record). The
+ * other is that a record already exists at the aligned startino that considers
+ * the newly allocated range as sparse. In the latter case, record content is
+ * merged in hope that sparse inode chunks fill to full chunks over time.
+ */
+STATIC void
+xfs_align_sparse_ino(
+ struct xfs_mount *mp,
+ xfs_agino_t *startino,
+ uint16_t *allocmask)
+{
+ xfs_agblock_t agbno;
+ xfs_agblock_t mod;
+ int offset;
+
+ agbno = XFS_AGINO_TO_AGBNO(mp, *startino);
+ mod = agbno % mp->m_sb.sb_inoalignmt;
+ if (!mod)
+ return;
+
+ /* calculate the inode offset and align startino */
+ offset = mod << mp->m_sb.sb_inopblog;
+ *startino -= offset;
+
+ /*
+ * Since startino has been aligned down, left shift allocmask such that
+ * it continues to represent the same physical inodes relative to the
+ * new startino.
+ */
+ *allocmask <<= offset / XFS_INODES_PER_HOLEMASK_BIT;
+}
+
+/*
+ * Determine whether the source inode record can merge into the target. Both
+ * records must be sparse, the inode ranges must match and there must be no
+ * allocation overlap between the records.
+ */
+STATIC bool
+__xfs_inobt_can_merge(
+ struct xfs_inobt_rec_incore *trec, /* tgt record */
+ struct xfs_inobt_rec_incore *srec) /* src record */
+{
+ uint64_t talloc;
+ uint64_t salloc;
+
+ /* records must cover the same inode range */
+ if (trec->ir_startino != srec->ir_startino)
+ return false;
+
+ /* both records must be sparse */
+ if (!xfs_inobt_issparse(trec->ir_holemask) ||
+ !xfs_inobt_issparse(srec->ir_holemask))
+ return false;
+
+ /* both records must track some inodes */
+ if (!trec->ir_count || !srec->ir_count)
+ return false;
+
+ /* can't exceed capacity of a full record */
+ if (trec->ir_count + srec->ir_count > XFS_INODES_PER_CHUNK)
+ return false;
+
+ /* verify there is no allocation overlap */
+ talloc = xfs_inobt_irec_to_allocmask(trec);
+ salloc = xfs_inobt_irec_to_allocmask(srec);
+ if (talloc & salloc)
+ return false;
+
+ return true;
+}
+
+/*
+ * Merge the source inode record into the target. The caller must call
+ * __xfs_inobt_can_merge() to ensure the merge is valid.
+ */
+STATIC void
+__xfs_inobt_rec_merge(
+ struct xfs_inobt_rec_incore *trec, /* target */
+ struct xfs_inobt_rec_incore *srec) /* src */
+{
+ ASSERT(trec->ir_startino == srec->ir_startino);
+
+ /* combine the counts */
+ trec->ir_count += srec->ir_count;
+ trec->ir_freecount += srec->ir_freecount;
+
+ /*
+ * Merge the holemask and free mask. For both fields, 0 bits refer to
+ * allocated inodes. We combine the allocated ranges with bitwise AND.
+ */
+ trec->ir_holemask &= srec->ir_holemask;
+ trec->ir_free &= srec->ir_free;
+}
+
+/*
+ * Insert a new sparse inode chunk into the associated inode btree. The inode
+ * record for the sparse chunk is pre-aligned to a startino that should match
+ * any pre-existing sparse inode record in the tree. This allows sparse chunks
+ * to fill over time.
+ *
+ * This function supports two modes of handling preexisting records depending on
+ * the merge flag. If merge is true, the provided record is merged with the
+ * existing record and updated in place. The merged record is returned in nrec.
+ * If merge is false, an existing record is replaced with the provided record.
+ * If no preexisting record exists, the provided record is always inserted.
+ *
+ * It is considered corruption if a merge is requested and not possible. Given
+ * the sparse inode alignment constraints, this should never happen.
+ */
+STATIC int
+xfs_inobt_insert_sprec(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_buf *agbp,
+ int btnum,
+ struct xfs_inobt_rec_incore *nrec, /* in/out: new/merged rec. */
+ bool merge) /* merge or replace */
+{
+ struct xfs_btree_cur *cur;
+ struct xfs_agi *agi = XFS_BUF_TO_AGI(agbp);
+ xfs_agnumber_t agno = be32_to_cpu(agi->agi_seqno);
+ int error;
+ int i;
+ struct xfs_inobt_rec_incore rec;
+
+ cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, btnum);
+
+ /* the new record is pre-aligned so we know where to look */
+ error = xfs_inobt_lookup(cur, nrec->ir_startino, XFS_LOOKUP_EQ, &i);
+ if (error)
+ goto error;
+ /* if nothing there, insert a new record and return */
+ if (i == 0) {
+ error = xfs_inobt_insert_rec(cur, nrec->ir_holemask,
+ nrec->ir_count, nrec->ir_freecount,
+ nrec->ir_free, &i);
+ if (error)
+ goto error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, error);
+
+ goto out;
+ }
+
+ /*
+ * A record exists at this startino. Merge or replace the record
+ * depending on what we've been asked to do.
+ */
+ if (merge) {
+ error = xfs_inobt_get_rec(cur, &rec, &i);
+ if (error)
+ goto error;
+ XFS_WANT_CORRUPTED_GOTO(mp, i == 1, error);
+ XFS_WANT_CORRUPTED_GOTO(mp,
+ rec.ir_startino == nrec->ir_startino,
+ error);
+
+ /*
+ * This should never fail. If we have coexisting records that
+ * cannot merge, something is seriously wrong.
+ */
+ XFS_WANT_CORRUPTED_GOTO(mp, __xfs_inobt_can_merge(nrec, &rec),
+ error);
+
+ trace_xfs_irec_merge_pre(mp, agno, rec.ir_startino,
+ rec.ir_holemask, nrec->ir_startino,
+ nrec->ir_holemask);
+
+ /* merge to nrec to output the updated record */
+ __xfs_inobt_rec_merge(nrec, &rec);
+
+ trace_xfs_irec_merge_post(mp, agno, nrec->ir_startino,
+ nrec->ir_holemask);
+
+ error = xfs_inobt_rec_check_count(mp, nrec);
+ if (error)
+ goto error;
+ }
+
+ error = xfs_inobt_update(cur, nrec);
+ if (error)
+ goto error;
+
+out:
+ xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
+ return 0;
+error:
+ xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+ return error;
+}
+
+/*
* Allocate new inodes in the allocation group specified by agbp.
* Return 0 for success, else error code.
*/
@@ -395,6 +603,8 @@ xfs_ialloc_ag_alloc(
xfs_agino_t newlen; /* new number of inodes */
int isaligned = 0; /* inode allocation at stripe unit */
/* boundary */
+ uint16_t allocmask = (uint16_t) -1; /* init. to full chunk */
+ struct xfs_inobt_rec_incore rec;
struct xfs_perag *pag;

memset(&args, 0, sizeof(args));
@@ -511,6 +721,45 @@ xfs_ialloc_ag_alloc(
return error;
}

+ /*
+ * Finally, try a sparse allocation if the filesystem supports it and
+ * the sparse allocation length is smaller than a full chunk.
+ */
+ if (xfs_sb_version_hassparseinodes(&args.mp->m_sb) &&
+ args.mp->m_ialloc_min_blks < args.mp->m_ialloc_blks &&
+ args.fsbno == NULLFSBLOCK) {
+ args.type = XFS_ALLOCTYPE_NEAR_BNO;
+ args.agbno = be32_to_cpu(agi->agi_root);
+ args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
+ args.alignment = args.mp->m_sb.sb_spino_align;
+ args.prod = 1;
+
+ args.minlen = args.mp->m_ialloc_min_blks;
+ args.maxlen = args.minlen;
+
+ /*
+ * The inode record will be aligned to full chunk size. We must
+ * prevent sparse allocation from AG boundaries that result in
+ * invalid inode records, such as records that start at agbno 0
+ * or extend beyond the AG.
+ *
+ * Set min agbno to the first aligned, non-zero agbno and max to
+ * the last aligned agbno that is at least one full chunk from
+ * the end of the AG.
+ */
+ args.min_agbno = args.mp->m_sb.sb_inoalignmt;
+ args.max_agbno = round_down(args.mp->m_sb.sb_agblocks,
+ args.mp->m_sb.sb_inoalignmt) -
+ args.mp->m_ialloc_blks;
+
+ error = xfs_alloc_vextent(&args);
+ if (error)
+ return error;
+
+ newlen = args.len << args.mp->m_sb.sb_inopblog;
+ allocmask = (1 << (newlen / XFS_INODES_PER_HOLEMASK_BIT)) - 1;
+ }
+
if (args.fsbno == NULLFSBLOCK) {
*alloc = 0;
return 0;
@@ -535,6 +784,73 @@ xfs_ialloc_ag_alloc(
* Convert the results.
*/
newino = XFS_OFFBNO_TO_AGINO(args.mp, args.agbno, 0);
+
+ if (xfs_inobt_issparse(~allocmask)) {
+ /*
+ * We've allocated a sparse chunk. Align the startino and mask.
+ */
+ xfs_align_sparse_ino(args.mp, &newino, &allocmask);
+
+ rec.ir_startino = newino;
+ rec.ir_holemask = ~allocmask;
+ rec.ir_count = newlen;
+ rec.ir_freecount = newlen;
+ rec.ir_free = XFS_INOBT_ALL_FREE;
+
+ /*
+ * Insert the sparse record into the inobt and allow for a merge
+ * if necessary. If a merge does occur, rec is updated to the
+ * merged record.
+ */
+ error = xfs_inobt_insert_sprec(args.mp, tp, agbp, XFS_BTNUM_INO,
+ &rec, true);
+ if (error == -EFSCORRUPTED) {
+ xfs_alert(args.mp,
+ "invalid sparse inode record: ino 0x%llx holemask 0x%x count %u",
+ XFS_AGINO_TO_INO(args.mp, agno,
+ rec.ir_startino),
+ rec.ir_holemask, rec.ir_count);
+ xfs_force_shutdown(args.mp, SHUTDOWN_CORRUPT_INCORE);
+ }
+ if (error)
+ return error;
+
+ /*
+ * We can't merge the part we've just allocated as for the inobt
+ * due to finobt semantics. The original record may or may not
+ * exist independent of whether physical inodes exist in this
+ * sparse chunk.
+ *
+ * We must update the finobt record based on the inobt record.
+ * rec contains the fully merged and up to date inobt record
+ * from the previous call. Set merge false to replace any
+ * existing record with this one.
+ */
+ if (xfs_sb_version_hasfinobt(&args.mp->m_sb)) {
+ error = xfs_inobt_insert_sprec(args.mp, tp, agbp,
+ XFS_BTNUM_FINO, &rec,
+ false);
+ if (error)
+ return error;
+ }
+ } else {
+ /* full chunk - insert new records to both btrees */
+ error = xfs_inobt_insert(args.mp, tp, agbp, newino, newlen,
+ XFS_BTNUM_INO);
+ if (error)
+ return error;
+
+ if (xfs_sb_version_hasfinobt(&args.mp->m_sb)) {
+ error = xfs_inobt_insert(args.mp, tp, agbp, newino,
+ newlen, XFS_BTNUM_FINO);
+ if (error)
+ return error;
+ }
+ }
+
+ /*
+ * Update AGI counts and newino.
+ */
be32_add_cpu(&agi->agi_count, newlen);
be32_add_cpu(&agi->agi_freecount, newlen);
pag = xfs_perag_get(args.mp, agno);
@@ -543,20 +859,6 @@ xfs_ialloc_ag_alloc(
agi->agi_newino = cpu_to_be32(newino);

/*
- * Insert records describing the new inode chunk into the btrees.
- */
- error = xfs_inobt_insert(args.mp, tp, agbp, newino, newlen,
- XFS_BTNUM_INO);
- if (error)
- return error;
-
- if (xfs_sb_version_hasfinobt(&args.mp->m_sb)) {
- error = xfs_inobt_insert(args.mp, tp, agbp, newino, newlen,
- XFS_BTNUM_FINO);
- if (error)
- return error;
- }
- /*
* Log allocation group header fields
*/
xfs_ialloc_log_agi(tp, agbp,
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index aa13b46..674ad8f 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -478,3 +478,34 @@ xfs_inobt_irec_to_allocmask(

return bitmap;
}
+
+#if defined(DEBUG) || defined(XFS_WARN)
+/*
+ * Verify that an in-core inode record has a valid inode count.
+ */
+int
+xfs_inobt_rec_check_count(
+ struct xfs_mount *mp,
+ struct xfs_inobt_rec_incore *rec)
+{
+ int inocount = 0;
+ int nextbit = 0;
+ uint64_t allocbmap;
+ int wordsz;
+
+ wordsz = sizeof(allocbmap) / sizeof(unsigned int);
+ allocbmap = xfs_inobt_irec_to_allocmask(rec);
+
+ nextbit = xfs_next_bit((uint *) &allocbmap, wordsz, nextbit);
+ while (nextbit != -1) {
+ inocount++;
+ nextbit = xfs_next_bit((uint *) &allocbmap, wordsz,
+ nextbit + 1);
+ }
+
+ if (inocount != rec->ir_count)
+ return -EFSCORRUPTED;
+
+ return 0;
+}
+#endif /* DEBUG */
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.h b/fs/xfs/libxfs/xfs_ialloc_btree.h
index 2c581ba..bd88453 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.h
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.h
@@ -65,4 +65,11 @@ extern int xfs_inobt_maxrecs(struct xfs_mount *, int, int);
/* ir_holemask to inode allocation bitmap conversion */
uint64_t xfs_inobt_irec_to_allocmask(struct xfs_inobt_rec_incore *);

+#if defined(DEBUG) || defined(XFS_WARN)
+int xfs_inobt_rec_check_count(struct xfs_mount *,
+ struct xfs_inobt_rec_incore *);
+#else
+#define xfs_inobt_rec_check_count(mp, rec) 0
+#endif /* DEBUG */
+
#endif /* __XFS_IALLOC_BTREE_H__ */
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index b1e059b..2ba5528 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -737,6 +737,53 @@ TRACE_EVENT(xfs_iomap_prealloc_size,
__entry->blocks, __entry->shift, __entry->writeio_blocks)
)

+TRACE_EVENT(xfs_irec_merge_pre,
+ TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agino_t agino,
+ uint16_t holemask, xfs_agino_t nagino, uint16_t nholemask),
+ TP_ARGS(mp, agno, agino, holemask, nagino, nholemask),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(xfs_agnumber_t, agno)
+ __field(xfs_agino_t, agino)
+ __field(uint16_t, holemask)
+ __field(xfs_agino_t, nagino)
+ __field(uint16_t, nholemask)
+ ),
+ TP_fast_assign(
+ __entry->dev = mp->m_super->s_dev;
+ __entry->agno = agno;
+ __entry->agino = agino;
+ __entry->holemask = holemask;
+ __entry->nagino = nagino;
+ __entry->nholemask = holemask;
+ ),
+ TP_printk("dev %d:%d agno %d inobt (%u:0x%x) new (%u:0x%x)",
+ MAJOR(__entry->dev), MINOR(__entry->dev), __entry->agno,
+ __entry->agino, __entry->holemask, __entry->nagino,
+ __entry->nholemask)
+)
+
+TRACE_EVENT(xfs_irec_merge_post,
+ TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agino_t agino,
+ uint16_t holemask),
+ TP_ARGS(mp, agno, agino, holemask),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(xfs_agnumber_t, agno)
+ __field(xfs_agino_t, agino)
+ __field(uint16_t, holemask)
+ ),
+ TP_fast_assign(
+ __entry->dev = mp->m_super->s_dev;
+ __entry->agno = agno;
+ __entry->agino = agino;
+ __entry->holemask = holemask;
+ ),
+ TP_printk("dev %d:%d agno %d inobt (%u:0x%x)", MAJOR(__entry->dev),
+ MINOR(__entry->dev), __entry->agno, __entry->agino,
+ __entry->holemask)
+)
+
#define DEFINE_IREF_EVENT(name) \
DEFINE_EVENT(xfs_iref_class, name, \
TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip), \