Re: 2.4.28-pre2 and ntfs-2.1.6b ?

From: O.Sezer
Date: Thu Aug 26 2004 - 18:14:18 EST


Willy Tarreau wrote:
Hi,

On Thu, Aug 26, 2004 at 11:59:47PM +0300, O.Sezer wrote:

Hi all:

With 2.4.28-pre2, ntfs-2.1.6b from linux-ntfs site
started failing to compile at aops.c:

aops.c: In function `ntfs_read_block':
aops.c:315: parse error before "else"
-- or in case of gcc3.4 --
aops.c:315: error: syntax error before "else"

This happens with gcc-3.2.2 and gcc-3.4.0
and can be fixed by:

--- aops.c.BAK 2004-08-26 19:35:11.000000000 +0300
+++ aops.c 2004-08-26 21:41:53.000000000 +0300
@@ -310,10 +310,11 @@
return 0;
}
/* No i/o was scheduled on any of the buffers. */
- if (likely(!PageError(page)))
+ if (likely(!PageError(page))) {
SetPageUptodate(page);
- else /* Signal synchronous i/o error. */
+ } else { /* Signal synchronous i/o error. */
nr = -EIO;
+ }
unlock_page(page);
return nr;
}


No !
Please don't fix it this way ! The problem lies within the declaration of
SetPageUptodate() which it seems is a macro which lacks some braces somewhere.
You were very lucky that there was an 'else' to point it out, but imagine
what it would do in the following case :

if (likely(!PageError(page))) {
SetPageUptodate(page);
blah();

It would always execute the second half of SetPageUptodate(), whatever
the condition, and nothing will alert you.

What does SetPageUptodate() look like ?


The very same code used to compile fine with
2.4.27 without any changes to it.


I think that the gcc-3.4 fixes might have hit some sensible parts...


I can't see
where the problem is (it's 23:57 here ;)).
Can anyone tell, please?


It's even later now, good night :-)

Regards,
Willy

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Hi Willy, and thanks, you're a lifesaver! All the evidence points
to the s390 changes in -pre2, specificly cset-1.1514 by schwidefsky
which touches include/linux/mm.h this way:

--- 1.44/include/linux/mm.h 2004-08-26 15:51:04 -07:00
+++ 1.45/include/linux/mm.h 2004-08-26 15:51:04 -07:00
@@ -308,11 +308,9 @@
/* Make it prettier to test the above... */
#define UnlockPage(page) unlock_page(page)
#define Page_Uptodate(page) test_bit(PG_uptodate, &(page)->flags)
-#define SetPageUptodate(page) \
- do { \
- arch_set_page_uptodate(page); \
- set_bit(PG_uptodate, &(page)->flags); \
- } while (0)
+#ifndef SetPageUptodate
+#define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags);
+#endif
#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
#define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)

Marcelo, you maybe interested in this.

Cheers,
Ozkan Sezer
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