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 <[email protected]>
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c 2007-09-14 13:51:55.000000000 +0200
+++ linux-2.6/mm/memory.c 2007-09-14 13:55:41.000000000 +0200
@@ -2003,50 +2003,49 @@ 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;
- 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);
+ 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;
- /*
- * 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);
+ /*
+ * 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);
+ }
-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);
-
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