clean up vmtruncate

vmtruncate is a twisted maze of gotos, this patch cleans it up to have a
proper if else for the two major cases of extending and truncating truncate
and thus makes it a lot more readable while keeping exactly the same
functinality.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index bc13775..b7cb2e0 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1909,50 +1909,49 @@ EXPORT_SYMBOL(unmap_mapping_range);
  */
 int vmtruncate(struct inode * inode, loff_t offset)
 {
-       struct address_space *mapping = inode->i_mapping;
-       unsigned long limit;
+       if (inode->i_size < offset) {
+               unsigned long limit;
+
+               limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+               if (limit != RLIM_INFINITY && offset > limit)
+                       goto out_sig;
+               if (offset > inode->i_sb->s_maxbytes)
+                       goto out_big;
+               i_size_write(inode, offset);
+       } else {
+               struct address_space *mapping = inode->i_mapping;
 
-       if (inode->i_size < offset)
-               goto do_expand;
-       /*
-        * truncation of in-use swapfiles is disallowed - it would cause
-        * subsequent swapout to scribble on the now-freed blocks.
-        */
-       if (IS_SWAPFILE(inode))
-               goto out_busy;
-       i_size_write(inode, offset);
+               /*
+                * truncation of in-use swapfiles is disallowed - it would
+                * cause subsequent swapout to scribble on the now-freed
+                * blocks.
+                */
+               if (IS_SWAPFILE(inode))
+                       return -ETXTBSY;
+               i_size_write(inode, offset);
+
+               /*
+                * unmap_mapping_range is called twice, first simply for
+                * efficiency so that truncate_inode_pages does fewer
+                * single-page unmaps.  However after this first call, and
+                * before truncate_inode_pages finishes, it is possible for
+                * private pages to be COWed, which remain after
+                * truncate_inode_pages finishes, hence the second
+                * unmap_mapping_range call must be made for correctness.
+                */
+               unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
+               truncate_inode_pages(mapping, offset);
+               unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
+       }
 
-       /*
-        * unmap_mapping_range is called twice, first simply for efficiency
-        * so that truncate_inode_pages does fewer single-page unmaps. However
-        * after this first call, and before truncate_inode_pages finishes,
-        * it is possible for private pages to be COWed, which remain after
-        * truncate_inode_pages finishes, hence the second unmap_mapping_range
-        * call must be made for correctness.
-        */
-       unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
-       truncate_inode_pages(mapping, offset);
-       unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
-       goto out_truncate;
-
-do_expand:
-       limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
-       if (limit != RLIM_INFINITY && offset > limit)
-               goto out_sig;
-       if (offset > inode->i_sb->s_maxbytes)
-               goto out_big;
-       i_size_write(inode, offset);
-
-out_truncate:
        if (inode->i_op && inode->i_op->truncate)
                inode->i_op->truncate(inode);
        return 0;
+
 out_sig:
        send_sig(SIGXFSZ, current, 0);
 out_big:
        return -EFBIG;
-out_busy:
-       return -ETXTBSY;
 }
 EXPORT_SYMBOL(vmtruncate);