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>

1 files changed, 34 insertions, 35 deletions

diff --git a/mm/memory.c b/mm/memory.c
index bc137751da7f..b7cb2e01705f 100644
--- 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);