[patch 1/12] misc fixes

[patch 1/12] misc fixes

[Andrew Morton]

- Remove the IO error warning in end_buffer_io_sync().  Failed READA
  attempts trigger it.

- Emit a warning when an ext2 is mounting an ext3 filesystem.

  We have had quite a few problem reports related to this, mainly
  arising from initrd problems.  And mount(8) tends to report the
  fstype from /etc/fstab rather than reporting what has really
  happened.

Fixes some bogosity which I added to max_block():

- `size' doesn't need to be sector_t

- `retval' should not be initialised to "~0UL" because that is
  0x00000000ffffffff with 64-bit sector_t.

- /proc/partitions shows wrong number of blocks (Badari Pulavarty)

- Allocate task_structs with GFP_KERNEL, as discussed.

- Convert the EXPORT_SYMBOL for generic_file_direct_IO() to
  EXPORT_SYMBOL_GPL.  That was only exported as a practicality for the
  raw driver.

- Make the loop thread run balance_dirty_pages() after dirtying the
  backing file.  So it will perform writeback of the backing file when
  dirty memory levels are high.  Export balance_dirty_pages to GPL
  modules for this.

  This makes loop work a lot better - I suspect it broke when callers
  of balance_dirty_pages() started writing back only their own queue.

  There are many page allocation failures under heavy loop writeout. 
  Coming from blk_queue_bounce()'s allocation from the page_pool
  mempool.  So...

- Disable page allocation warnings around the initial atomic
  allocation attempt in mempool_alloc() - the one where __GFP_WAIT and
  __GFP_IO were turned off.  That one can easily fail.

- Add some commentary in block_write_full_page()


 drivers/block/genhd.c |    2 +-
 drivers/block/loop.c  |    2 ++
 fs/block_dev.c        |    6 +++---
 fs/buffer.c           |   13 +++++++++++--
 fs/ext2/super.c       |    3 +++
 kernel/fork.c         |    5 +++--
 kernel/ksyms.c        |    2 +-
 mm/mempool.c          |    2 ++
 mm/page-writeback.c   |    1 +
 9 files changed, 27 insertions, 9 deletions

--- 2.5.30/fs/buffer.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/fs/buffer.c	Fri Aug  9 17:37:02 2002
@@ -180,7 +180,10 @@ void end_buffer_io_sync(struct buffer_he
 	if (uptodate) {
 		set_buffer_uptodate(bh);
 	} else {
-		buffer_io_error(bh);
+		/*
+		 * This happens, due to failed READA attempts.
+		 * buffer_io_error(bh);
+		 */
 		clear_buffer_uptodate(bh);
 	}
 	unlock_buffer(bh);
@@ -2283,7 +2286,13 @@ int block_write_full_page(struct page *p
 		return -EIO;
 	}
 
-	/* The page straddles i_size */
+	/*
+	 * The page straddles i_size.  It must be zeroed out on each and every
+	 * writepage invokation because it may be mmapped.  "A file is mapped
+	 * in multiples of the page size.  For a file that is not a multiple of
+	 * the  page size, the remaining memory is zeroed when mapped, and
+	 * writes to that region are not written out to the file."
+	 */
 	kaddr = kmap(page);
 	memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
 	flush_dcache_page(page);
--- 2.5.30/fs/block_dev.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/fs/block_dev.c	Fri Aug  9 17:37:00 2002
@@ -26,12 +26,12 @@
 
 static sector_t max_block(struct block_device *bdev)
 {
-	sector_t retval = ~0U;
+	sector_t retval = ~0;
 	loff_t sz = bdev->bd_inode->i_size;
 
 	if (sz) {
-		sector_t size = block_size(bdev);
-		unsigned sizebits = blksize_bits(size);
+		unsigned int size = block_size(bdev);
+		unsigned int sizebits = blksize_bits(size);
 		retval = (sz >> sizebits);
 	}
 	return retval;
--- 2.5.30/fs/ext2/super.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/fs/ext2/super.c	Fri Aug  9 17:36:38 2002
@@ -698,6 +698,9 @@ static int ext2_fill_super(struct super_
 			printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 		goto failed_mount2;
 	}
+	if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
+		ext2_warning(sb, __FUNCTION__,
+			"mounting ext3 filesystem as ext2\n");
 	ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 	return 0;
 failed_mount2:
--- 2.5.30/drivers/block/genhd.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/drivers/block/genhd.c	Fri Aug  9 17:36:38 2002
@@ -166,7 +166,7 @@ static int show_partition(struct seq_fil
 			continue;
 		seq_printf(part, "%4d  %4d %10ld %s\n",
 			sgp->major, n + sgp->first_minor,
-			sgp->part[n].nr_sects << 1,
+			sgp->part[n].nr_sects >> 1,
 			disk_name(sgp, n + sgp->first_minor, buf));
 	}
 
--- 2.5.30/kernel/fork.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/kernel/fork.c	Fri Aug  9 17:36:38 2002
@@ -106,9 +106,10 @@ static struct task_struct *dup_task_stru
 	struct thread_info *ti;
 
 	ti = alloc_thread_info();
-	if (!ti) return NULL;
+	if (!ti)
+		return NULL;
 
-	tsk = kmem_cache_alloc(task_struct_cachep,GFP_ATOMIC);
+	tsk = kmem_cache_alloc(task_struct_cachep, GFP_KERNEL);
 	if (!tsk) {
 		free_thread_info(ti);
 		return NULL;
--- 2.5.30/kernel/ksyms.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/kernel/ksyms.c	Fri Aug  9 17:36:38 2002
@@ -342,7 +342,7 @@ EXPORT_SYMBOL(register_disk);
 EXPORT_SYMBOL(read_dev_sector);
 EXPORT_SYMBOL(init_buffer);
 EXPORT_SYMBOL(wipe_partitions);
-EXPORT_SYMBOL(generic_file_direct_IO);
+EXPORT_SYMBOL_GPL(generic_file_direct_IO);
 
 /* tty routines */
 EXPORT_SYMBOL(tty_hangup);
--- 2.5.30/drivers/block/loop.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/drivers/block/loop.c	Fri Aug  9 17:37:02 2002
@@ -74,6 +74,7 @@
 #include <linux/slab.h>
 #include <linux/loop.h>
 #include <linux/suspend.h>
+#include <linux/writeback.h>
 #include <linux/buffer_head.h>		/* for invalidate_bdev() */
 
 #include <asm/uaccess.h>
@@ -235,6 +236,7 @@ do_lo_send(struct loop_device *lo, struc
 	up(&mapping->host->i_sem);
 out:
 	kunmap(bvec->bv_page);
+	balance_dirty_pages(mapping);
 	return ret;
 
 unlock:
--- 2.5.30/mm/page-writeback.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/mm/page-writeback.c	Fri Aug  9 17:37:00 2002
@@ -133,6 +133,7 @@ void balance_dirty_pages(struct address_
 	if (!writeback_in_progress(bdi) && ps.nr_dirty > background_thresh)
 		pdflush_operation(background_writeout, 0);
 }
+EXPORT_SYMBOL_GPL(balance_dirty_pages);
 
 /**
  * balance_dirty_pages_ratelimited - balance dirty memory state
--- 2.5.30/mm/mempool.c~misc	Fri Aug  9 17:36:38 2002
+++ 2.5.30-akpm/mm/mempool.c	Fri Aug  9 17:36:38 2002
@@ -189,7 +189,9 @@ void * mempool_alloc(mempool_t *pool, in
 	int gfp_nowait = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
 
 repeat_alloc:
+	current->flags |= PF_NOWARN;
 	element = pool->alloc(gfp_nowait, pool->pool_data);
+	current->flags &= ~PF_NOWARN;
 	if (likely(element != NULL))
 		return element;
 

.

Re: [patch 1/12] misc fixes

[David S. Miller]

   From: Andrew Morton <akpm@zip.com.au>
   Date: Fri, 09 Aug 2002 17:55:24 -0700
   
   - `retval' should not be initialised to "~0UL" because that is
     0x00000000ffffffff with 64-bit sector_t.
   
'0' defaults to 'int' on 32-bit systems so ~0 isn't right either.

What I think you really want is "~(sector_t) 0".

Re: [patch 1/12] misc fixes

[Anton Altaparmakov]

At 02:24 10/08/02, David S. Miller wrote:
>    From: Andrew Morton <akpm@zip.com.au>
>    Date: Fri, 09 Aug 2002 17:55:24 -0700
>
>    - `retval' should not be initialised to "~0UL" because that is
>      0x00000000ffffffff with 64-bit sector_t.
>
>'0' defaults to 'int' on 32-bit systems so ~0 isn't right either.
>
>What I think you really want is "~(sector_t) 0".

Actually, ~0 is fine. This is because of the associativity of events 
happening. Breaking it down into individual ops as the compiler sees it:

1) constant 0 -> int type
2) ~0 -> (int)-1
3) assign to larger type sector_t -> sign extend smaller type to size of 
larger type -> (sector_t)-1

Therefore not specifying anything after the initial constant definition 
_always_ works because of sign extension and the order of evaluation which 
is guaranteed by the C language.

OTOH if you hard code 0U or 0L or 0UL or whatever it breaks because it 
forces the compiler not to sign extend and assume this to be a hardvalue, 
which is zero extended.

Note I just tried all possible combinations with a little test program and 
both assignments and binary operators work as expected (with sign 
extension) when the constant is given without qualifiers and both break 
horribly (no sign extension) when the constant is given with qualifiers.

I did this testing for another reason, and that is PAGE_MASK and 
PAGE_CACHE_MASK which break when used for 64-bit values on 32-bit 
architectures exactly for the above outlined reasons.

If no one beats me to it I will submit a patch to change PAGE_SIZE (and 
thus automatically PAGE_CACHE_SIZE) on all architectures to no longer use 
the "UL" type qualifier which is responsible for the breakage. This 
supersedes my previous ugly patch introducing a PAGE_{CACHE_,}MASK_LL...

Best regards,

         Anton


-- 
   "I've not lost my mind. It's backed up on tape somewhere." - Unknown
-- 
Anton Altaparmakov <aia21 at cantab.net> (replace at with @)
Linux NTFS Maintainer / IRC: #ntfs on irc.openprojects.net
WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/

Re: [patch 1/12] misc fixes

[Marcin Dalecki]

Anton Altaparmakov wrote:
>
> If no one beats me to it I will submit a patch to change PAGE_SIZE (and 
> thus automatically PAGE_CACHE_SIZE) on all architectures to no longer 
> use the "UL" type qualifier which is responsible for the breakage. This 
> supersedes my previous ugly patch introducing a PAGE_{CACHE_,}MASK_LL...


Just for the record - If you actually try to compile the kernel with a
C++ compiler it will warn you nicely about the particular issue here.