7 files changed, 64 insertions, 42 deletions

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 26673a0b20e7..56d1614760cf 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -175,7 +175,7 @@ xfs_buf_get_maps(
         bp->b_map_count = map_count;
 
         if (map_count == 1) {
-                bp->b_maps = &bp->b_map;
+                bp->b_maps = &bp->__b_map;
                 return 0;
         }
 
@@ -193,7 +193,7 @@ static void
 xfs_buf_free_maps(
         struct xfs_buf  *bp)
 {
-        if (bp->b_maps != &bp->b_map) {
+        if (bp->b_maps != &bp->__b_map) {
                 kmem_free(bp->b_maps);
                 bp->b_maps = NULL;
         }
@@ -377,8 +377,8 @@ xfs_buf_allocate_memory(
         }
 
 use_alloc_page:
-        start = BBTOB(bp->b_map.bm_bn) >> PAGE_SHIFT;
-        end = (BBTOB(bp->b_map.bm_bn + bp->b_length) + PAGE_SIZE - 1)
+        start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;
+        end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)
                                                                 >> PAGE_SHIFT;
         page_count = end - start;
         error = _xfs_buf_get_pages(bp, page_count, flags);
@@ -640,7 +640,7 @@ _xfs_buf_read(
         xfs_buf_flags_t         flags)
 {
         ASSERT(!(flags & XBF_WRITE));
-        ASSERT(bp->b_map.bm_bn != XFS_BUF_DADDR_NULL);
+        ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
 
         bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
         bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
@@ -1709,7 +1709,7 @@ xfs_buf_cmp(
         struct xfs_buf  *bp = container_of(b, struct xfs_buf, b_list);
         xfs_daddr_t             diff;
 
-        diff = ap->b_map.bm_bn - bp->b_map.bm_bn;
+        diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
         if (diff < 0)
                 return -1;
         if (diff > 0)
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 23f5642480bb..433a12ed7b17 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -151,7 +151,7 @@ typedef struct xfs_buf {
         struct page             **b_pages;      /* array of page pointers */
         struct page             *b_page_array[XB_PAGES]; /* inline pages */
         struct xfs_buf_map      *b_maps;        /* compound buffer map */
-        struct xfs_buf_map      b_map;          /* inline compound buffer map */
+        struct xfs_buf_map      __b_map;        /* inline compound buffer map */
         int                     b_map_count;
         int                     b_io_length;    /* IO size in BBs */
         atomic_t                b_pin_count;    /* pin count */
@@ -330,8 +330,8 @@ void xfs_buf_stale(struct xfs_buf *bp);
  * In future, uncached buffers will pass the block number directly to the io
  * request function and hence these macros will go away at that point.
  */
-#define XFS_BUF_ADDR(bp)                ((bp)->b_map.bm_bn)
-#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_map.bm_bn = (xfs_daddr_t)(bno))
+#define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
+#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 
 static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 {
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index becf4a97efc6..77b09750e92c 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -71,7 +71,7 @@ xfs_buf_item_log_debug(
                 chunk_num = byte >> XFS_BLF_SHIFT;
                 word_num = chunk_num >> BIT_TO_WORD_SHIFT;
                 bit_num = chunk_num & (NBWORD - 1);
-                wordp = &(bip->bli_format.blf_data_map[word_num]);
+                wordp = &(bip->__bli_format.blf_data_map[word_num]);
                 bit_set = *wordp & (1 << bit_num);
                 ASSERT(bit_set);
                 byte++;
@@ -237,7 +237,7 @@ xfs_buf_item_size(
                  * cancel flag in it.
                  */
                 trace_xfs_buf_item_size_stale(bip);
-                ASSERT(bip->bli_format.blf_flags & XFS_BLF_CANCEL);
+                ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
                 return bip->bli_format_count;
         }
 
@@ -278,7 +278,7 @@ xfs_buf_item_format_segment(
         uint            buffer_offset;
 
         /* copy the flags across from the base format item */
-        blfp->blf_flags = bip->bli_format.blf_flags;
+        blfp->blf_flags = bip->__bli_format.blf_flags;
 
         /*
          * Base size is the actual size of the ondisk structure - it reflects
@@ -287,6 +287,17 @@ xfs_buf_item_format_segment(
          */
         base_size = offsetof(struct xfs_buf_log_format, blf_data_map) +
                         (blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
+
+        nvecs = 0;
+        first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
+        if (!(bip->bli_flags & XFS_BLI_STALE) && first_bit == -1) {
+                /*
+                 * If the map is not be dirty in the transaction, mark
+                 * the size as zero and do not advance the vector pointer.
+                 */
+                goto out;
+        }
+
         vecp->i_addr = blfp;
         vecp->i_len = base_size;
         vecp->i_type = XLOG_REG_TYPE_BFORMAT;
@@ -301,15 +312,13 @@ xfs_buf_item_format_segment(
                  */
                 trace_xfs_buf_item_format_stale(bip);
                 ASSERT(blfp->blf_flags & XFS_BLF_CANCEL);
-                blfp->blf_size = nvecs;
-                return vecp;
+                goto out;
         }
 
         /*
          * Fill in an iovec for each set of contiguous chunks.
          */
-        first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
-        ASSERT(first_bit != -1);
+
         last_bit = first_bit;
         nbits = 1;
         for (;;) {
@@ -371,7 +380,8 @@ xfs_buf_item_format_segment(
                         nbits++;
                 }
         }
-        bip->bli_format.blf_size = nvecs;
+out:
+        blfp->blf_size = nvecs;
         return vecp;
 }
 
@@ -405,7 +415,7 @@ xfs_buf_item_format(
         if (bip->bli_flags & XFS_BLI_INODE_BUF) {
                 if (!((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&
                       xfs_log_item_in_current_chkpt(lip)))
-                        bip->bli_format.blf_flags |= XFS_BLF_INODE_BUF;
+                        bip->__bli_format.blf_flags |= XFS_BLF_INODE_BUF;
                 bip->bli_flags &= ~XFS_BLI_INODE_BUF;
         }
 
@@ -485,7 +495,7 @@ xfs_buf_item_unpin(
                 ASSERT(bip->bli_flags & XFS_BLI_STALE);
                 ASSERT(xfs_buf_islocked(bp));
                 ASSERT(XFS_BUF_ISSTALE(bp));