qnx4: new helper - try_extent()

checking if an extent is the one we are looking for is done twice
in qnx4_block_map(); gather that code into a helper function.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/qnx4/inode.c b/fs/qnx4/inode.c
index 7900a81..552e994 100644 (file)
--- a/fs/qnx4/inode.c
+++ b/fs/qnx4/inode.c
@@ -66,23 +66,31 @@ static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_h
        return 0;
 }
 
+static inline u32 try_extent(qnx4_xtnt_t *extent, u32 *offset)
+{
+       u32 size = le32_to_cpu(extent->xtnt_size);
+       if (*offset < size)
+               return le32_to_cpu(extent->xtnt_blk) + *offset - 1;
+       *offset -= size;
+       return 0;
+}
+
 unsigned long qnx4_block_map( struct inode *inode, long iblock )
 {
        int ix;
-       long offset, i_xblk;
-       unsigned long block = 0;
+       long i_xblk;
        struct buffer_head *bh = NULL;
        struct qnx4_xblk *xblk = NULL;
        struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
        u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);
+       u32 offset = iblock;
+       u32 block = try_extent(&qnx4_inode->di_first_xtnt, &offset);
 
-       if ( iblock < le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size) ) {
+       if (block) {
                // iblock is in the first extent. This is easy.
-               block = le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_blk) + iblock - 1;
        } else {
                // iblock is beyond first extent. We have to follow the extent chain.
                i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
-               offset = iblock - le32_to_cpu(qnx4_inode->di_first_xtnt.xtnt_size);
                ix = 0;
                while ( --nxtnt > 0 ) {
                        if ( ix == 0 ) {
@@ -98,12 +106,11 @@ unsigned long qnx4_block_map( struct inode *inode, long iblock )
                                        return -EIO;
                                }
                        }
-                       if ( offset < le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size) ) {
+                       block = try_extent(&xblk->xblk_xtnts[ix], &offset);
+                       if (block) {
                                // got it!
-                               block = le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_blk) + offset - 1;
                                break;
                        }
-                       offset -= le32_to_cpu(xblk->xblk_xtnts[ix].xtnt_size);
                        if ( ++ix >= xblk->xblk_num_xtnts ) {
                                i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
                                ix = 0;