Merge branch 'xfs-sparse-inode' into for-next

16 files changed, 829 insertions, 86 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 516162be1398..bc78ac08e72e 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -149,13 +149,27 @@ xfs_alloc_compute_aligned(
 {
         xfs_agblock_t   bno;
         xfs_extlen_t    len;
+        xfs_extlen_t    diff;
 
         /* Trim busy sections out of found extent */
         xfs_extent_busy_trim(args, foundbno, foundlen, &bno, &len);
 
+        /*
+         * If we have a largish extent that happens to start before min_agbno,
+         * see if we can shift it into range...
+         */
+        if (bno < args->min_agbno && bno + len > args->min_agbno) {
+                diff = args->min_agbno - bno;
+                if (len > diff) {
+                        bno += diff;
+                        len -= diff;
+                }
+        }
+
         if (args->alignment > 1 && len >= args->minlen) {
                 xfs_agblock_t   aligned_bno = roundup(bno, args->alignment);
-                xfs_extlen_t    diff = aligned_bno - bno;
+
+                diff = aligned_bno - bno;
 
                 *resbno = aligned_bno;
                 *reslen = diff >= len ? 0 : len - diff;
@@ -795,9 +809,13 @@ xfs_alloc_find_best_extent(
                  * The good extent is closer than this one.
                  */
                 if (!dir) {
+                        if (*sbnoa > args->max_agbno)
+                                goto out_use_good;
                         if (*sbnoa >= args->agbno + gdiff)
                                 goto out_use_good;
                 } else {
+                        if (*sbnoa < args->min_agbno)
+                                goto out_use_good;
                         if (*sbnoa <= args->agbno - gdiff)
                                 goto out_use_good;
                 }
@@ -884,6 +902,17 @@ xfs_alloc_ag_vextent_near(
         dofirst = prandom_u32() & 1;
 #endif
 
+        /* handle unitialized agbno range so caller doesn't have to */
+        if (!args->min_agbno && !args->max_agbno)
+                args->max_agbno = args->mp->m_sb.sb_agblocks - 1;
+        ASSERT(args->min_agbno <= args->max_agbno);
+
+        /* clamp agbno to the range if it's outside */
+        if (args->agbno < args->min_agbno)
+                args->agbno = args->min_agbno;
+        if (args->agbno > args->max_agbno)
+                args->agbno = args->max_agbno;
+
 restart:
         bno_cur_lt = NULL;
         bno_cur_gt = NULL;
@@ -976,6 +1005,8 @@ restart:
                                                   &ltbnoa, &ltlena);
                         if (ltlena < args->minlen)
                                 continue;
+                        if (ltbnoa < args->min_agbno || ltbnoa > args->max_agbno)
+                                continue;
                         args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
                         xfs_alloc_fix_len(args);
                         ASSERT(args->len >= args->minlen);
@@ -1096,11 +1127,11 @@ restart:
                         XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
                         xfs_alloc_compute_aligned(args, ltbno, ltlen,
                                                   &ltbnoa, &ltlena);
-                        if (ltlena >= args->minlen)
+                        if (ltlena >= args->minlen && ltbnoa >= args->min_agbno)
                                 break;
                         if ((error = xfs_btree_decrement(bno_cur_lt, 0, &i)))
                                 goto error0;
-                        if (!i) {
+                        if (!i || ltbnoa < args->min_agbno) {
                                 xfs_btree_del_cursor(bno_cur_lt,
                                                      XFS_BTREE_NOERROR);
                                 bno_cur_lt = NULL;
@@ -1112,11 +1143,11 @@ restart:
                         XFS_WANT_CORRUPTED_GOTO(args->mp, i == 1, error0);
                         xfs_alloc_compute_aligned(args, gtbno, gtlen,
                                                   &gtbnoa, &gtlena);
-                        if (gtlena >= args->minlen)
+                        if (gtlena >= args->minlen && gtbnoa <= args->max_agbno)
                                 break;
                         if ((error = xfs_btree_increment(bno_cur_gt, 0, &i)))
                                 goto error0;
-                        if (!i) {
+                        if (!i || gtbnoa > args->max_agbno) {
                                 xfs_btree_del_cursor(bno_cur_gt,
                                                      XFS_BTREE_NOERROR);
                                 bno_cur_gt = NULL;
@@ -1216,6 +1247,7 @@ restart:
         ASSERT(ltnew >= ltbno);
         ASSERT(ltnew + rlen <= ltbnoa + ltlena);
         ASSERT(ltnew + rlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
+        ASSERT(ltnew >= args->min_agbno && ltnew <= args->max_agbno);
         args->agbno = ltnew;
 
         if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno, ltlen,
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index d1b4b6a5c894..29f27b272b7f 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -112,6 +112,8 @@ typedef struct xfs_alloc_arg {
         xfs_extlen_t    total;          /* total blocks needed in xaction */
         xfs_extlen_t    alignment;      /* align answer to multiple of this */
         xfs_extlen_t    minalignslop;   /* slop for minlen+alignment calcs */
+        xfs_agblock_t   min_agbno;      /* set an agbno range for NEAR allocs */
+        xfs_agblock_t   max_agbno;      /* ... */
         xfs_extlen_t    len;            /* output: actual size of extent */
         xfs_alloctype_t type;           /* allocation type XFS_ALLOCTYPE_... */
         xfs_alloctype_t otype;          /* original allocation type */
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index ff22a4d9ad0c..815f61b02bc1 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -170,7 +170,7 @@ typedef struct xfs_sb {
         __uint32_t      sb_features_log_incompat;
 
         __uint32_t      sb_crc;         /* superblock crc */
-        __uint32_t      sb_pad;
+        xfs_extlen_t    sb_spino_align; /* sparse inode chunk alignment */
 
         xfs_ino_t       sb_pquotino;    /* project quota inode */
         xfs_lsn_t       sb_lsn;         /* last write sequence */
@@ -256,7 +256,7 @@ typedef struct xfs_dsb {
         __be32          sb_features_log_incompat;
 
         __le32          sb_crc;         /* superblock crc */
-        __be32          sb_pad;
+        __be32          sb_spino_align; /* sparse inode chunk alignment */
 
         __be64          sb_pquotino;    /* project quota inode */
         __be64          sb_lsn;         /* last write sequence */
@@ -457,8 +457,10 @@ xfs_sb_has_ro_compat_feature(
 }
 
 #define XFS_SB_FEAT_INCOMPAT_FTYPE      (1 << 0)        /* filetype in dirent */
+#define XFS_SB_FEAT_INCOMPAT_SPINODES   (1 << 1)        /* sparse inode chunks */
 #define XFS_SB_FEAT_INCOMPAT_ALL \
-                (XFS_SB_FEAT_INCOMPAT_FTYPE)
+                (XFS_SB_FEAT_INCOMPAT_FTYPE|    \
+                 XFS_SB_FEAT_INCOMPAT_SPINODES)
 
 #define XFS_SB_FEAT_INCOMPAT_UNKNOWN    ~XFS_SB_FEAT_INCOMPAT_ALL
 static inline bool
@@ -506,6 +508,12 @@ static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
                 (sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_FINOBT);
 }
 
+static inline bool xfs_sb_version_hassparseinodes(struct xfs_sb *sbp)
+{
+        return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
+                xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_SPINODES);
+}
+
 /*
  * end of superblock version macros
  */
@@ -1216,26 +1224,54 @@ typedef	__uint64_t	xfs_inofree_t;
 #define XFS_INOBT_ALL_FREE              ((xfs_inofree_t)-1)
 #define XFS_INOBT_MASK(i)               ((xfs_inofree_t)1 << (i))
 
+#define XFS_INOBT_HOLEMASK_FULL         0       /* holemask for full chunk */
+#define XFS_INOBT_HOLEMASK_BITS         (NBBY * sizeof(__uint16_t))
+#define XFS_INODES_PER_HOLEMASK_BIT     \
+        (XFS_INODES_PER_CHUNK / (NBBY * sizeof(__uint16_t)))
+
 static inline xfs_inofree_t xfs_inobt_maskn(int i, int n)
 {
         return ((n >= XFS_INODES_PER_CHUNK ? 0 : XFS_INOBT_MASK(n)) - 1) << i;
 }
 
 /*
- * Data record structure
+ * The on-disk inode record structure has two formats. The original "full"
+ * format uses a 4-byte freecount. The "sparse" format uses a 1-byte freecount
+ * and replaces the 3 high-order freecount bytes wth the holemask and inode
+ * count.
+ *
+ * The holemask of the sparse record format allows an inode chunk to have holes
+ * that refer to blocks not owned by the inode record. This facilitates inode
+ * allocation in the event of severe free space fragmentation.
  */
 typedef struct xfs_inobt_rec {
         __be32          ir_startino;    /* starting inode number */
-        __be32          ir_freecount;   /* count of free inodes (set bits) */
+        union {
+                struct {
+                        __be32  ir_freecount;   /* count of free inodes */
+                } f;
+                struct {
+                        __be16  ir_holemask;/* hole mask for sparse chunks */
+                        __u8    ir_count;       /* total inode count */
+                        __u8    ir_freecount;   /* count of free inodes */
+                } sp;
+        } ir_u;
         __be64          ir_free;        /* free inode mask */
 } xfs_inobt_rec_t;
 
 typedef struct xfs_inobt_rec_incore {
         xfs_agino_t     ir_startino;    /* starting inode number */
-        __int32_t       ir_freecount;   /* count of free inodes (set bits) */
+        __uint16_t      ir_holemask;    /* hole mask for sparse chunks */
+        __uint8_t       ir_count;       /* total inode count */
+        __uint8_t       ir_freecount;   /* count of free inodes (set bits) */
         xfs_inofree_t   ir_free;        /* free inode mask */
 } xfs_inobt_rec_incore_t;
 
+static inline bool xfs_inobt_issparse(uint16_t holemask)
+{
+        /* non-zero holemask represents a sparse rec. */
+        return holemask;
+}
 
 /*
  * Key structure
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 18dc721ca19f..89689c6a43e2 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -239,6 +239,7 @@ typedef struct xfs_fsop_resblks {
 #define XFS_FSOP_GEOM_FLAGS_V5SB        0x8000  /* version 5 superblock */
 #define XFS_FSOP_GEOM_FLAGS_FTYPE       0x10000 /* inode directory types */
 #define XFS_FSOP_GEOM_FLAGS_FINOBT      0x20000 /* free inode btree */
+#define XFS_FSOP_GEOM_FLAGS_SPINODES    0x40000 /* sparse inode chunks  */
 
 /*
  * Minimum and maximum sizes need for growth checks.
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 1c9e75521250..a18bc75cc216 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -65,6 +65,8 @@ xfs_inobt_lookup(
         int                     *stat)  /* success/failure */
 {
         cur->bc_rec.i.ir_startino = ino;
+        cur->bc_rec.i.ir_holemask = 0;
+        cur->bc_rec.i.ir_count = 0;
         cur->bc_rec.i.ir_freecount = 0;
         cur->bc_rec.i.ir_free = 0;
         return xfs_btree_lookup(cur, dir, stat);
@@ -82,7 +84,14 @@ xfs_inobt_update(
         union xfs_btree_rec     rec;
 
         rec.inobt.ir_startino = cpu_to_be32(irec->ir_startino);
-        rec.inobt.ir_freecount = cpu_to_be32(irec->ir_freecount);
+        if (xfs_sb_version_hassparseinodes(&cur->bc_mp->m_sb)) {
+                rec.inobt.ir_u.sp.ir_holemask = cpu_to_be16(irec->ir_holemask);
+                rec.inobt.ir_u.sp.ir_count = irec->ir_count;
+                rec.inobt.ir_u.sp.ir_freecount = irec->ir_freecount;
+        } else {
+                /* ir_holemask/ir_count not supported on-disk */
+                rec.inobt.ir_u.f.ir_freecount = cpu_to_be32(irec->ir_freecount);
+        }
         rec.inobt.ir_free = cpu_to_be64(irec->ir_free);
         return xfs_btree_update(cur, &rec);
 }
@@ -100,12 +109,27 @@ xfs_inobt_get_rec(
         int                     error;
 
         error = xfs_btree_get_rec(cur, &rec, stat);
-        if (!error && *stat == 1) {
-                irec->ir_startino = be32_to_cpu(rec->inobt.ir_startino);
-                irec->ir_freecount = be32_to_cpu(rec->inobt.ir_freecount);
-                irec->ir_free = be64_to_cpu(rec->inobt.ir_free);
+        if (error || *stat == 0)
+                return error;
+
+        irec->ir_startino = be32_to_cpu(rec->inobt.ir_startino);
+        if (xfs_sb_version_hassparseinodes(&cur->bc_mp->m_sb)) {
+                irec->ir_holemask = be16_to_cpu(rec->inobt.ir_u.sp.ir_holemask);
+                irec->ir_count = rec->inobt.ir_u.sp.ir_count;
+                irec->ir_freecount = rec->inobt.ir_u.sp.ir_freecount;
+        } else {
+                /*
+                 * ir_holemask/ir_count not supported on-disk. Fill in hardcoded
+                 * values for full inode chunks.
+                 */
+                irec->ir_holemask = XFS_INOBT_HOLEMASK_FULL;
+                irec->ir_count = XFS_INODES_PER_CHUNK;
+                irec->ir_freecount =
+                                be32_to_cpu(rec->inobt.ir_u.f.ir_freecount);
         }
-        return error;
+        irec->ir_free = be64_to_cpu(rec->inobt.ir_free);
+
+        return 0;
 }
 
 /*
@@ -114,10 +138,14 @@ xfs_inobt_get_rec(
 STATIC int
 xfs_inobt_insert_rec(
         struct xfs_btree_cur    *cur,
+        __uint16_t              holemask,
+        __uint8_t               count,
         __int32_t               freecount,
         xfs_inofree_t           free,
         int                     *stat)
 {
+        cur->bc_rec.i.ir_holemask = holemask;
+        cur->bc_rec.i.ir_count = count;
         cur->bc_rec.i.ir_freecount = freecount;
         cur->bc_rec.i.ir_free = free;
         return xfs_btree_insert(cur, stat);
@@ -154,7 +182,9 @@ xfs_inobt_insert(
                 }
                 ASSERT(i == 0);
 
-                error = xfs_inobt_insert_rec(cur, XFS_INODES_PER_CHUNK,
+                error = xfs_inobt_insert_rec(cur, XFS_INOBT_HOLEMASK_FULL,
+                                             XFS_INODES_PER_CHUNK,
+                                             XFS_INODES_PER_CHUNK,
                                              XFS_INOBT_ALL_FREE, &i);
                 if (error) {
                         xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
@@ -220,6 +250,7 @@ xfs_ialloc_inode_init(
         struct xfs_mount        *mp,
         struct xfs_trans        *tp,
         struct list_head        *buffer_list,
+        int                     icount,
         xfs_agnumber_t          agno,
         xfs_agblock_t           agbno,
         xfs_agblock_t           length,
@@ -275,7 +306,7 @@ xfs_ialloc_inode_init(
                  * they track in the AIL as if they were physically logged.
                  */
                 if (tp)
-                        xfs_icreate_log(tp, agno, agbno, mp->m_ialloc_inos,
+                        xfs_icreate_log(tp, agno, agbno, icount,
                                         mp->m_sb.sb_inodesize, length, gen);
         } else
                 version = 2;
@@ -347,6 +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.
  */
@@ -364,11 +603,22 @@ 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;
 
+        int             do_sparse = 0;
+
+#ifdef DEBUG
+        /* randomly do sparse inode allocations */
+        if (xfs_sb_version_hassparseinodes(&tp->t_mountp->m_sb))
+                do_sparse = prandom_u32() & 1;
+#endif
+
         memset(&args, 0, sizeof(args));
         args.tp = tp;
         args.mp = tp->t_mountp;
+        args.fsbno = NULLFSBLOCK;
 
         /*
          * Locking will ensure that we don't have two callers in here
@@ -390,6 +640,8 @@ xfs_ialloc_ag_alloc(
         agno = be32_to_cpu(agi->agi_seqno);
         args.agbno = XFS_AGINO_TO_AGBNO(args.mp, newino) +
                      args.mp->m_ialloc_blks;
+        if (do_sparse)
+                goto sparse_alloc;
         if (likely(newino != NULLAGINO &&
                   (args.agbno < be32_to_cpu(agi->agi_length)))) {
                 args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
@@ -428,8 +680,7 @@ xfs_ialloc_ag_alloc(
                  * subsequent requests.
                  */
                 args.minalignslop = 0;
-        } else
-                args.fsbno = NULLFSBLOCK;
+        }
 
         if (unlikely(args.fsbno == NULLFSBLOCK)) {
                 /*
@@ -480,6 +731,46 @@ 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) {
+sparse_alloc:
+                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;
@@ -495,8 +786,8 @@ xfs_ialloc_ag_alloc(
          * rather than a linear progression to prevent the next generation
          * number from being easily guessable.
          */
-        error = xfs_ialloc_inode_init(args.mp, tp, NULL, agno, args.agbno,
-                        args.len, prandom_u32());
+        error = xfs_ialloc_inode_init(args.mp, tp, NULL, newlen, agno,
+                        args.agbno, args.len, prandom_u32());
 
         if (error)
                 return error;
@@ -504,6 +795,73 @@ 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);
@@ -512,20 +870,6 @@ 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,
@@ -645,7 +989,7 @@ xfs_ialloc_ag_select(
                  * if we fail allocation due to alignment issues then it is most
                  * likely a real ENOSPC condition.
                  */
-                ineed = mp->m_ialloc_blks;
+                ineed = mp->m_ialloc_min_blks;
                 if (flags && ineed > 1)
                         ineed += xfs_ialloc_cluster_alignment(mp);
                 longest = pag->pagf_longest;
@@ -732,6 +1076,27 @@ xfs_ialloc_get_rec(
 }
 
 /*
+ * Return the offset of the first free inode in the record. If the inode chunk
+ * is sparsely allocated, we convert the record holemask to inode granularity
+ * and mask off the unallocated regions from the inode free mask.
+ */
+STATIC int
+xfs_inobt_first_free_inode(
+        struct xfs_inobt_rec_incore     *rec)
+{
+        xfs_inofree_t                   realfree;
+
+        /* if there are no holes, return the first available offset */
+        if (!xfs_inobt_issparse(rec->ir_holemask))
+                return xfs_lowbit64(rec->ir_free);
+
+        realfree = xfs_inobt_irec_to_allocmask(rec);
+        realfree &= rec->ir_free;
+
+        return xfs_lowbit64(realfree);
+}
+
+/*
  * Allocate an inode using the inobt-only algorithm.
  */
 STATIC int
@@ -961,7 +1326,7 @@ newino:
         }
 
 alloc_inode:
-        offset = xfs_lowbit64(rec.ir_free);
+        offset = xfs_inobt_first_free_inode(&rec);
         ASSERT(offset >= 0);
         ASSERT(offset < XFS_INODES_PER_CHUNK);
         ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
@@ -1210,7 +1575,7 @@ xfs_dialloc_ag(
         if (error)
                 goto error_cur;
 
-        offset = xfs_lowbit64(rec.ir_free);
+        offset = xfs_inobt_first_free_inode(&rec);
         ASSERT(offset >= 0);
         ASSERT(offset < XFS_INODES_PER_CHUNK);
         ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
@@ -1439,6 +1804,83 @@ out_error:
         return error;
 }
 
+/*
+ * Free the blocks of an inode chunk. We must consider that the inode chunk
+ * might be sparse and only free the regions that are allocated as part of the
+ * chunk.
+ */
+STATIC void
+xfs_difree_inode_chunk(
+        struct xfs_mount                *mp,
+        xfs_agnumber_t                  agno,
+        struct xfs_inobt_rec_incore     *rec,
+        struct xfs_bmap_free            *flist)
+{
+        xfs_agblock_t   sagbno = XFS_AGINO_TO_AGBNO(mp, rec->ir_startino);
+        int             startidx, endidx;
+        int             nextbit;
+        xfs_agblock_t   agbno;
+        int             contigblk;
+        DECLARE_BITMAP(holemask, XFS_INOBT_HOLEMASK_BITS);
+
+        if (!xfs_inobt_issparse(rec->ir_holemask)) {
+                /* not sparse, calculate extent info directly */
+                xfs_bmap_add_free(XFS_AGB_TO_FSB(mp, agno,
+                                  XFS_AGINO_TO_AGBNO(mp, rec->ir_startino)),
+                                  mp->m_ialloc_blks, flist, mp);
+                return;
+        }
+
+        /* holemask is only 16-bits (fits in an unsigned long) */
+        ASSERT(sizeof(rec->ir_holemask) <= sizeof(holemask[0]));
+        holemask[0] = rec->ir_holemask;
+
+        /*
+         * Find contiguous ranges of zeroes (i.e., allocated regions) in the
+         * holemask and convert the start/end index of each range to an extent.
+         * We start with the start and end index both pointing at the first 0 in
+         * the mask.
+         */
+        startidx = endidx = find_first_zero_bit(holemask,
+                                                XFS_INOBT_HOLEMASK_BITS);
+        nextbit = startidx + 1;
+        while (startidx < XFS_INOBT_HOLEMASK_BITS) {
+                nextbit = find_next_zero_bit(holemask, XFS_INOBT_HOLEMASK_BITS,
+                                             nextbit);
+                /*
+                 * If the next zero bit is contiguous, update the end index of
+                 * the current range and continue.
+                 */
+                if (nextbit != XFS_INOBT_HOLEMASK_BITS &&
+                    nextbit == endidx + 1) {
+                        endidx = nextbit;
+                        goto next;
+                }
+
+                /*
+                 * nextbit is not contiguous with the current end index. Convert
+                 * the current start/end to an extent and add it to the free
+                 * list.
+                 */
+                agbno = sagbno + (startidx * XFS_INODES_PER_HOLEMASK_BIT) /
+                                  mp->m_sb.sb_inopblock;
+                contigblk = ((endidx - startidx + 1) *
+                             XFS_INODES_PER_HOLEMASK_BIT) /
+                            mp->m_sb.sb_inopblock;
+
+                ASSERT(agbno % mp->m_sb.sb_spino_align == 0);
+                ASSERT(contigblk % mp->m_sb.sb_spino_align == 0);
+                xfs_bmap_add_free(XFS_AGB_TO_FSB(mp, agno, agbno), contigblk,
+                                  flist, mp);
+
+                /* reset range to current bit and carry on... */
+                startidx = endidx = nextbit;
+
+next:
+                nextbit++;
+        }
+}
+
 STATIC int
 xfs_difree_inobt(
         struct xfs_mount                *mp,
@@ -1446,8 +1888,7 @@ xfs_difree_inobt(
         struct xfs_buf                  *agbp,
         xfs_agino_t                     agino,
         struct xfs_bmap_free            *flist,
-        int                             *deleted,
-        xfs_ino_t                       *first_ino,
+        struct xfs_icluster             *xic,
         struct xfs_inobt_rec_incore     *orec)
 {
         struct xfs_agi                  *agi = XFS_BUF_TO_AGI(agbp);
@@ -1501,20 +1942,23 @@ xfs_difree_inobt(
         rec.ir_freecount++;
 
         /*
-         * When an inode cluster is free, it becomes eligible for removal
+         * When an inode chunk is free, it becomes eligible for removal. Don't
+         * remove the chunk if the block size is large enough for multiple inode
+         * chunks (that might not be free).
          */
         if (!(mp->m_flags & XFS_MOUNT_IKEEP) &&
-            (rec.ir_freecount == mp->m_ialloc_inos)) {
-
-                *deleted = 1;
-                *first_ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino);
+            rec.ir_free == XFS_INOBT_ALL_FREE &&
+            mp->m_sb.sb_inopblock <= XFS_INODES_PER_CHUNK) {
+                xic->deleted = 1;
+                xic->first_ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino);
+                xic->alloc = xfs_inobt_irec_to_allocmask(&rec);
 
                 /*
                  * Remove the inode cluster from the AGI B+Tree, adjust the
                  * AGI and Superblock inode counts, and mark the disk space
                  * to be freed when the transaction is committed.
                  */
-                ilen = mp->m_ialloc_inos;
+                ilen = rec.ir_freecount;
                 be32_add_cpu(&agi->agi_count, -ilen);
                 be32_add_cpu(&agi->agi_freecount, -(ilen - 1));
                 xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
@@ -1530,11 +1974,9 @@ xfs_difree_inobt(
                         goto error0;
                 }
 
-                xfs_bmap_add_free(XFS_AGB_TO_FSB(mp, agno,
-                                  XFS_AGINO_TO_AGBNO(mp, rec.ir_startino)),
-                                  mp->m_ialloc_blks, flist, mp);
+                xfs_difree_inode_chunk(mp, agno, &rec, flist);
         } else {
-                *deleted = 0;
+                xic->deleted = 0;
 
                 error = xfs_inobt_update(cur, &rec);
                 if (error) {
@@ -1599,7 +2041,9 @@ xfs_difree_finobt(
                  */
                 XFS_WANT_CORRUPTED_GOTO(mp, ibtrec->ir_freecount == 1, error);
 
-                error = xfs_inobt_insert_rec(cur, ibtrec->ir_freecount,
+                error = xfs_inobt_insert_rec(cur, ibtrec->ir_holemask,
+                                             ibtrec->ir_count,
+                                             ibtrec->ir_freecount,
                                              ibtrec->ir_free, &i);
                 if (error)
                         goto error;
@@ -1634,8 +2078,13 @@ xfs_difree_finobt(
          * free inode. Hence, if all of the inodes are free and we aren't
          * keeping inode chunks permanently on disk, remove the record.
          * Otherwise, update the record with the new information.
+         *
+         * Note that we currently can't free chunks when the block size is large
+         * enough for multiple chunks. Leave the finobt record to remain in sync
+         * with the inobt.
          */
-        if (rec.ir_freecount == mp->m_ialloc_inos &&
+        if (rec.ir_free == XFS_INOBT_ALL_FREE &&
+            mp->m_sb.sb_inopblock <= XFS_INODES_PER_CHUNK &&
             !(mp->m_flags & XFS_MOUNT_IKEEP)) {
                 error = xfs_btree_delete(cur, &i);
                 if (error)
@@ -1671,8 +2120,7 @@ xfs_difree(
         struct xfs_trans        *tp,            /* transaction pointer */
         xfs_ino_t               inode,          /* inode to be freed */
         struct xfs_bmap_free    *flist,         /* extents to free */
-        int                     *deleted,/* set if inode cluster was deleted */
-        xfs_ino_t               *first_ino)/* first inode in deleted cluster */
+        struct xfs_icluster     *xic)   /* cluster info if deleted */
 {
         /* REFERENCED */
         xfs_agblock_t           agbno;  /* block number containing inode */
@@ -1723,8 +2171,7 @@ xfs_difree(
         /*
          * Fix up the inode allocation btree.
          */
-        error = xfs_difree_inobt(mp, tp, agbp, agino, flist, deleted, first_ino,
-                                 &rec);
+        error = xfs_difree_inobt(mp, tp, agbp, agino, flist, xic, &rec);
         if (error)
                 goto error0;
 
diff --git a/fs/xfs/libxfs/xfs_ialloc.h b/fs/xfs/libxfs/xfs_ialloc.h
index 100007d56449..12401fea7bff 100644
--- a/fs/xfs/libxfs/xfs_ialloc.h
+++ b/fs/xfs/libxfs/xfs_ialloc.h
@@ -28,6 +28,13 @@ struct xfs_btree_cur;
 /* Move inodes in clusters of this size */
 #define XFS_INODE_BIG_CLUSTER_SIZE      8192
 
+struct xfs_icluster {
+        bool            deleted;        /* record is deleted */
+        xfs_ino_t       first_ino;      /* first inode number */
+        uint64_t        alloc;          /* inode phys. allocation bitmap for
+                                         * sparse chunks */
+};
+
 /* Calculate and return the number of filesystem blocks per inode cluster */
 static inline int
 xfs_icluster_size_fsb(
@@ -90,8 +97,7 @@ xfs_difree(
         struct xfs_trans *tp,           /* transaction pointer */
         xfs_ino_t       inode,          /* inode to be freed */
         struct xfs_bmap_free *flist,    /* extents to free */
-        int             *deleted,       /* set if inode cluster was deleted */
-        xfs_ino_t       *first_ino);    /* first inode in deleted cluster */
+        struct xfs_icluster *ifree);    /* cluster info if deleted */
 
 /*
  * Return the location of the inode in imap, for mapping it into a buffer.
@@ -156,7 +162,7 @@ int xfs_inobt_get_rec(struct xfs_btree_cur *cur,
  * Inode chunk initialisation routine
  */
 int xfs_ialloc_inode_init(struct xfs_mount *mp, struct xfs_trans *tp,
-                          struct list_head *buffer_list,
+                          struct list_head *buffer_list, int icount,
                           xfs_agnumber_t agno, xfs_agblock_t agbno,
                           xfs_agblock_t length, unsigned int gen);
 
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 964c465ca69c..674ad8f760be 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -167,7 +167,16 @@ xfs_inobt_init_rec_from_cur(
         union xfs_btree_rec     *rec)
 {
         rec->inobt.ir_startino = cpu_to_be32(cur->bc_rec.i.ir_startino);
-        rec->inobt.ir_freecount = cpu_to_be32(cur->bc_rec.i.ir_freecount);
+        if (xfs_sb_version_hassparseinodes(&cur->bc_mp->m_sb)) {
+                rec->inobt.ir_u.sp.ir_holemask =
+                                        cpu_to_be16(cur->bc_rec.i.ir_holemask);
+                rec->inobt.ir_u.sp.ir_count = cur->bc_rec.i.ir_count;
+                rec->inobt.ir_u.sp.ir_freecount = cur->bc_rec.i.ir_freecount;
+        } else {
+                /* ir_holemask/ir_count not supported on-disk */
+                rec->inobt.ir_u.f.ir_freecount =
+                                        cpu_to_be32(cur->bc_rec.i.ir_freecount);
+        }
         rec->inobt.ir_free = cpu_to_be64(cur->bc_rec.i.ir_free);
 }
 
@@ -418,3 +427,85 @@ xfs_inobt_maxrecs(
                 return blocklen / sizeof(xfs_inobt_rec_t);
         return blocklen / (sizeof(xfs_inobt_key_t) + sizeof(xfs_inobt_ptr_t));
 }
+
+/*
+ * Convert the inode record holemask to an inode allocation bitmap. The inode
+ * allocation bitmap is inode granularity and specifies whether an inode is
+ * physically allocated on disk (not whether the inode is considered allocated
+ * or free by the fs).
+ *
+ * A bit value of 1 means the inode is allocated, a value of 0 means it is free.
+ */
+uint64_t
+xfs_inobt_irec_to_allocmask(
+        struct xfs_inobt_rec_incore     *rec)
+{
+        uint64_t                        bitmap = 0;
+        uint64_t                        inodespbit;
+        int                             nextbit;
+        uint                            allocbitmap;
+
+        /*
+         * The holemask has 16-bits for a 64 inode record. Therefore each
+         * holemask bit represents multiple inodes. Create a mask of bits to set
+         * in the allocmask for each holemask bit.
+         */
+        inodespbit = (1 << XFS_INODES_PER_HOLEMASK_BIT) - 1;
+
+        /*
+         * Allocated inodes are represented by 0 bits in holemask. Invert the 0
+         * bits to 1 and convert to a uint so we can use xfs_next_bit(). Mask
+         * anything beyond the 16 holemask bits since this casts to a larger
+         * type.
+         */
+        allocbitmap = ~rec->ir_holemask & ((1 << XFS_INOBT_HOLEMASK_BITS) - 1);
+
+        /*
+         * allocbitmap is the inverted holemask so every set bit represents
+         * allocated inodes. To expand from 16-bit holemask granularity to
+         * 64-bit (e.g., bit-per-inode), set inodespbit bits in the target
+         * bitmap for every holemask bit.
+         */
+        nextbit = xfs_next_bit(&allocbitmap, 1, 0);
+        while (nextbit != -1) {
+                ASSERT(nextbit < (sizeof(rec->ir_holemask) * NBBY));
+
+                bitmap |= (inodespbit <<
+                           (nextbit * XFS_INODES_PER_HOLEMASK_BIT));
+
+                nextbit = xfs_next_bit(&allocbitmap, 1, nextbit + 1);
+        }
+
+        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 d7ebea72c2d0..bd88453217ce 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.h
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.h
@@ -62,4 +62,14 @@ extern struct xfs_btree_cur *xfs_inobt_init_cursor(struct xfs_mount *,
                 xfs_btnum_t);
 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/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index dc4bfc5d88fc..019dc324a146 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -174,6 +174,27 @@ xfs_mount_validate_sb(
                         return -EFSCORRUPTED;
         }
 
+        /*
+         * Full inode chunks must be aligned to inode chunk size when
+         * sparse inodes are enabled to support the sparse chunk
+         * allocation algorithm and prevent overlapping inode records.
+         */
+        if (xfs_sb_version_hassparseinodes(sbp)) {
+                uint32_t        align;
+
+                xfs_alert(mp,
+        "EXPERIMENTAL sparse inode feature enabled. Use at your own risk!");
+
+                align = XFS_INODES_PER_CHUNK * sbp->sb_inodesize
+                                >> sbp->sb_blocklog;
+                if (sbp->sb_inoalignmt != align) {
+                        xfs_warn(mp,
+"Inode block alignment (%u) must match chunk size (%u) for sparse inodes.",
+                                 sbp->sb_inoalignmt, align);
+                        return -EINVAL;
+                }
+        }
+
         if (unlikely(
             sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
                 xfs_warn(mp,
@@ -374,7 +395,7 @@ __xfs_sb_from_disk(
                                 be32_to_cpu(from->sb_features_log_incompat);
         /* crc is only used on disk, not in memory; just init to 0 here. */
         to->sb_crc = 0;
-        to->sb_pad = 0;
+        to->sb_spino_align = be32_to_cpu(from->sb_spino_align);
         to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
         to->sb_lsn = be64_to_cpu(from->sb_lsn);
         /* Convert on-disk flags to in-memory flags? */
@@ -516,7 +537,7 @@ xfs_sb_to_disk(
                                 cpu_to_be32(from->sb_features_incompat);
                 to->sb_features_log_incompat =
                                 cpu_to_be32(from->sb_features_log_incompat);
-                to->sb_pad = 0;
+                to->sb_spino_align = cpu_to_be32(from->sb_spino_align);
                 to->sb_lsn = cpu_to_be64(from->sb_lsn);
         }
 }
@@ -689,6 +710,11 @@ xfs_sb_mount_common(
         mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
                                         sbp->sb_inopblock);
         mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
+
+        if (sbp->sb_spino_align)
+                mp->m_ialloc_min_blks = sbp->sb_spino_align;
+        else
+                mp->m_ialloc_min_blks = mp->m_ialloc_blks;
 }
 
 /*
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index cb7e8a29dfb6..4bd6463cd931 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -101,7 +101,9 @@ xfs_fs_geometry(
                         (xfs_sb_version_hasftype(&mp->m_sb) ?
                                 XFS_FSOP_GEOM_FLAGS_FTYPE : 0) |
                         (xfs_sb_version_hasfinobt(&mp->m_sb) ?
-                                XFS_FSOP_GEOM_FLAGS_FINOBT : 0);
+                                XFS_FSOP_GEOM_FLAGS_FINOBT : 0) |
+                        (xfs_sb_version_hassparseinodes(&mp->m_sb) ?
+                                XFS_FSOP_GEOM_FLAGS_SPINODES : 0);
                 geo->logsectsize = xfs_sb_version_hassector(&mp->m_sb) ?
                                 mp->m_sb.sb_logsectsize : BBSIZE;
                 geo->rtsectsize = mp->m_sb.sb_blocksize;
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 539a85fddbc2..4c054f6634b9 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2235,9 +2235,9 @@ xfs_iunlink_remove(
  */
 STATIC int
 xfs_ifree_cluster(
-        xfs_inode_t     *free_ip,
-        xfs_trans_t     *tp,
-        xfs_ino_t       inum)
+        xfs_inode_t             *free_ip,
+        xfs_trans_t             *tp,
+        struct xfs_icluster     *xic)
 {
         xfs_mount_t             *mp = free_ip->i_mount;
         int                     blks_per_cluster;
@@ -2250,13 +2250,26 @@ xfs_ifree_cluster(
         xfs_inode_log_item_t    *iip;
         xfs_log_item_t          *lip;
         struct xfs_perag        *pag;
+        xfs_ino_t               inum;
 
+        inum = xic->first_ino;
         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, inum));
         blks_per_cluster = xfs_icluster_size_fsb(mp);
         inodes_per_cluster = blks_per_cluster << mp->m_sb.sb_inopblog;
         nbufs = mp->m_ialloc_blks / blks_per_cluster;
 
         for (j = 0; j < nbufs; j++, inum += inodes_per_cluster) {
+                /*
+                 * The allocation bitmap tells us which inodes of the chunk were
+                 * physically allocated. Skip the cluster if an inode falls into
+                 * a sparse region.
+                 */
+                if ((xic->alloc & XFS_INOBT_MASK(inum - xic->first_ino)) == 0) {
+                        ASSERT(((inum - xic->first_ino) %
+                                inodes_per_cluster) == 0);
+                        continue;
+                }
+
                 blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
                                          XFS_INO_TO_AGBNO(mp, inum));
 
@@ -2414,8 +2427,7 @@ xfs_ifree(
         xfs_bmap_free_t *flist)
 {
         int                     error;
-        int                     delete;
-        xfs_ino_t               first_ino;
+        struct xfs_icluster     xic = { 0 };
 
         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
         ASSERT(ip->i_d.di_nlink == 0);
@@ -2431,7 +2443,7 @@ xfs_ifree(
         if (error)
                 return error;
 
-        error = xfs_difree(tp, ip->i_ino, flist, &delete, &first_ino);
+        error = xfs_difree(tp, ip->i_ino, flist, &xic);
         if (error)
                 return error;
 
@@ -2448,8 +2460,8 @@ xfs_ifree(
         ip->i_d.di_gen++;
         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-        if (delete)
-                error = xfs_ifree_cluster(ip, tp, first_ino);
+        if (xic.deleted)
+                error = xfs_ifree_cluster(ip, tp, &xic);
 
         return error;
 }
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index 80429891dc9b..f41b0c3fddab 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -252,7 +252,7 @@ xfs_bulkstat_grab_ichunk(
                 }
 
                 irec->ir_free |= xfs_inobt_maskn(0, idx);
-                *icount = XFS_INODES_PER_CHUNK - irec->ir_freecount;
+                *icount = irec->ir_count - irec->ir_freecount;
         }
 
         return 0;
@@ -415,6 +415,8 @@ xfs_bulkstat(
                                 goto del_cursor;
                         if (icount) {
                                 irbp->ir_startino = r.ir_startino;
+                                irbp->ir_holemask = r.ir_holemask;
+                                irbp->ir_count = r.ir_count;
                                 irbp->ir_freecount = r.ir_freecount;
                                 irbp->ir_free = r.ir_free;
                                 irbp++;
@@ -447,13 +449,15 @@ xfs_bulkstat(
                          * If this chunk has any allocated inodes, save it.
                          * Also start read-ahead now for this chunk.
                          */
-                        if (r.ir_freecount < XFS_INODES_PER_CHUNK) {
+                        if (r.ir_freecount < r.ir_count) {
                                 xfs_bulkstat_ichunk_ra(mp, agno, &r);
                                 irbp->ir_startino = r.ir_startino;
+                                irbp->ir_holemask = r.ir_holemask;
+                                irbp->ir_count = r.ir_count;
                                 irbp->ir_freecount = r.ir_freecount;
                                 irbp->ir_free = r.ir_free;
                                 irbp++;
-                                icount += XFS_INODES_PER_CHUNK - r.ir_freecount;
+                                icount += r.ir_count - r.ir_freecount;
                         }
                         error = xfs_btree_increment(cur, 0, &stat);
                         if (error || stat == 0) {
@@ -599,8 +603,7 @@ xfs_inumbers(
                 agino = r.ir_startino + XFS_INODES_PER_CHUNK - 1;
                 buffer[bufidx].xi_startino =
                         XFS_AGINO_TO_INO(mp, agno, r.ir_startino);
-                buffer[bufidx].xi_alloccount =
-                        XFS_INODES_PER_CHUNK - r.ir_freecount;
+                buffer[bufidx].xi_alloccount = r.ir_count - r.ir_freecount;
                 buffer[bufidx].xi_allocmask = ~r.ir_free;
                 if (++bufidx == bcount) {
                         long    written;
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 4f5784f85a5b..4a8c440b6280 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -3068,12 +3068,22 @@ xlog_recover_do_icreate_pass2(
                 return -EINVAL;
         }
 
-        /* existing allocation is fixed value */
-        ASSERT(count == mp->m_ialloc_inos);
-        ASSERT(length == mp->m_ialloc_blks);
-        if (count != mp->m_ialloc_inos ||
-             length != mp->m_ialloc_blks) {
-                xfs_warn(log->l_mp, "xlog_recover_do_icreate_trans: bad count 2");
+        /*
+         * The inode chunk is either full or sparse and we only support
+         * m_ialloc_min_blks sized sparse allocations at this time.
+         */
+        if (length != mp->m_ialloc_blks &&
+            length != mp->m_ialloc_min_blks) {
+                xfs_warn(log->l_mp,
+                         "%s: unsupported chunk length", __FUNCTION__);
+                return -EINVAL;
+        }
+
+        /* verify inode count is consistent with extent length */
+        if ((count >> mp->m_sb.sb_inopblog) != length) {
+                xfs_warn(log->l_mp,
+                         "%s: inconsistent inode count and chunk length",
+                         __FUNCTION__);
                 return -EINVAL;
         }
 
@@ -3091,8 +3101,8 @@ xlog_recover_do_icreate_pass2(
                         XFS_AGB_TO_DADDR(mp, agno, agbno), length, 0))
                 return 0;
 
-        xfs_ialloc_inode_init(mp, NULL, buffer_list, agno, agbno, length,
-                                        be32_to_cpu(icl->icl_gen));
+        xfs_ialloc_inode_init(mp, NULL, buffer_list, count, agno, agbno, length,
+                              be32_to_cpu(icl->icl_gen));
         return 0;
 }
 
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 6f23fbdfb365..461e791efad7 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -725,6 +725,22 @@ xfs_mountfs(
         }
 
         /*
+         * If enabled, sparse inode chunk alignment is expected to match the
+         * cluster size. Full inode chunk alignment must match the chunk size,
+         * but that is checked on sb read verification...
+         */
+        if (xfs_sb_version_hassparseinodes(&mp->m_sb) &&
+            mp->m_sb.sb_spino_align !=
+                        XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size)) {
+                xfs_warn(mp,
+        "Sparse inode block alignment (%u) must match cluster size (%llu).",
+                         mp->m_sb.sb_spino_align,
+                         XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size));
+                error = -EINVAL;
+                goto out_remove_uuid;
+        }
+
+        /*
          * Set inode alignment fields
          */
         xfs_set_inoalignment(mp);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 8c995a2ccb6f..df209c290258 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -101,6 +101,8 @@ typedef struct xfs_mount {
         __uint64_t              m_flags;        /* global mount flags */
         int                     m_ialloc_inos;  /* inodes in inode allocation */
         int                     m_ialloc_blks;  /* blocks in inode allocation */
+        int                     m_ialloc_min_blks;/* min blocks in sparse inode
+                                                   * allocation */
         int                     m_inoalign_mask;/* mask sb_inoalignmt if used */
         uint                    m_qflags;       /* quota status flags */
         struct xfs_trans_resv   m_resv;         /* precomputed res values */
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 615781bf4ee5..8d916d33d93d 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -738,6 +738,53 @@ 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), \