xfs: limit xfs_imap_to_bmap to a single mapping

We only call xfs_iomap for single mappings anyway, so remove all
code dealing with multiple mappings from xfs_imap_to_bmap and add
asserts that we never get results that we do not expect.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 28 insertions, 36 deletions

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 0b65039951a0..2d9bce7fcf85 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -55,49 +55,41 @@
 #define XFS_STRAT_WRITE_IMAPS   2
 #define XFS_WRITE_IMAPS         XFS_BMAP_MAX_NMAP
 
-STATIC int
+STATIC void
 xfs_imap_to_bmap(
         xfs_inode_t     *ip,
         xfs_off_t       offset,
         xfs_bmbt_irec_t *imap,
         xfs_iomap_t     *iomapp,
         int             imaps,                  /* Number of imap entries */
-        int             iomaps,                 /* Number of iomap entries */
         int             flags)
 {
         xfs_mount_t     *mp = ip->i_mount;
-        int             pbm;
         xfs_fsblock_t   start_block;
 
+        iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
+        iomapp->iomap_delta = offset - iomapp->iomap_offset;
+        iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
+        iomapp->iomap_flags = flags;
 
-        for (pbm = 0; imaps && pbm < iomaps; imaps--, iomapp++, imap++, pbm++) {
-                iomapp->iomap_offset = XFS_FSB_TO_B(mp, imap->br_startoff);
-                iomapp->iomap_delta = offset - iomapp->iomap_offset;
-                iomapp->iomap_bsize = XFS_FSB_TO_B(mp, imap->br_blockcount);
-                iomapp->iomap_flags = flags;
-
-                if (XFS_IS_REALTIME_INODE(ip)) {
-                        iomapp->iomap_flags |= IOMAP_REALTIME;
-                        iomapp->iomap_target = mp->m_rtdev_targp;
-                } else {
-                        iomapp->iomap_target = mp->m_ddev_targp;
-                }
-                start_block = imap->br_startblock;
-                if (start_block == HOLESTARTBLOCK) {
-                        iomapp->iomap_bn = IOMAP_DADDR_NULL;
-                        iomapp->iomap_flags |= IOMAP_HOLE;
-                } else if (start_block == DELAYSTARTBLOCK) {
-                        iomapp->iomap_bn = IOMAP_DADDR_NULL;
-                        iomapp->iomap_flags |= IOMAP_DELAY;
-                } else {
-                        iomapp->iomap_bn = xfs_fsb_to_db(ip, start_block);
-                        if (ISUNWRITTEN(imap))
-                                iomapp->iomap_flags |= IOMAP_UNWRITTEN;
-                }
-
-                offset += iomapp->iomap_bsize - iomapp->iomap_delta;
+        if (XFS_IS_REALTIME_INODE(ip)) {
+                iomapp->iomap_flags |= IOMAP_REALTIME;
+                iomapp->iomap_target = mp->m_rtdev_targp;
+        } else {
+                iomapp->iomap_target = mp->m_ddev_targp;
+        }
+        start_block = imap->br_startblock;
+        if (start_block == HOLESTARTBLOCK) {
+                iomapp->iomap_bn = IOMAP_DADDR_NULL;
+                iomapp->iomap_flags |= IOMAP_HOLE;
+        } else if (start_block == DELAYSTARTBLOCK) {
+                iomapp->iomap_bn = IOMAP_DADDR_NULL;
+                iomapp->iomap_flags |= IOMAP_DELAY;
+        } else {
+                iomapp->iomap_bn = xfs_fsb_to_db(ip, start_block);
+                if (ISUNWRITTEN(imap))
+                        iomapp->iomap_flags |= IOMAP_UNWRITTEN;
         }
-        return pbm;     /* Return the number filled */
 }
 
 int
@@ -119,6 +111,7 @@ xfs_iomap(
         int             iomap_flags = 0;
 
         ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFREG);
+        ASSERT(niomaps && *niomaps == 1);
 
         if (XFS_FORCED_SHUTDOWN(mp))
                 return XFS_ERROR(EIO);
@@ -203,12 +196,11 @@ xfs_iomap(
                 break;
         }
 
-        if (nimaps) {
-                *niomaps = xfs_imap_to_bmap(ip, offset, &imap,
-                                            iomapp, nimaps, *niomaps, iomap_flags);
-        } else if (niomaps) {
-                *niomaps = 0;
-        }
+        ASSERT(nimaps <= 1);
+
+        if (nimaps)
+                xfs_imap_to_bmap(ip, offset, &imap, iomapp, nimaps, iomap_flags);
+        *niomaps = nimaps;
 
 out:
         if (lockmode)