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Date: Tue, 16 Jan 2007 17:15:02 +1100
From: David Chinner <dgc@....com>
To: Adrian Bunk <bunk@...sta.de>
Cc: Linus Torvalds <torvalds@...l.org>, Andrew Morton <akpm@...l.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Sami Farin <7atbggg02@...akemail.com>,
David Chinner <dgc@....com>, xfs-masters@....sgi.com
Subject: Re: 2.6.20-rc5: known unfixed regressions
On Sat, Jan 13, 2007 at 08:11:25AM +0100, Adrian Bunk wrote:
> On Fri, Jan 12, 2007 at 02:27:48PM -0500, Linus Torvalds wrote:
> >...
> > A lot of developers (including me) will be gone next week for
> > Linux.Conf.Au, so you have a week of rest and quiet to test this, and
> > report any problems.
> >
> > Not that there will be any, right? You all behave now!
> >...
>
> This still leaves the old regressions we have not yet fixed...
>
>
> This email lists some known regressions in 2.6.20-rc5 compared to 2.6.19.
>
>
> Subject : BUG: at mm/truncate.c:60 cancel_dirty_page() (XFS)
> References : http://lkml.org/lkml/2007/1/5/308
> Submitter : Sami Farin <7atbggg02@...akemail.com>
> Handled-By : David Chinner <dgc@....com>
> Status : problem is being discussed
I'm at LCA and been having laptop dramas so the fix is being held up at this
point. I and trying to test a change right now that adds an optional unmap
to truncate_inode_pages_range as XFS needs, in some circumstances, to toss
out dirty pages (with dirty bufferheads) and hence requires truncate semantics
that are currently missing unmap calls.
Semi-untested patch attached below.
Cheers,
Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
fs/xfs/linux-2.6/xfs_fs_subr.c | 6 ++--
include/linux/mm.h | 2 +
mm/truncate.c | 60 ++++++++++++++++++++++++++++++++++++-----
3 files changed, 60 insertions(+), 8 deletions(-)
Index: linux-2.6.19/fs/xfs/linux-2.6/xfs_fs_subr.c
===================================================================
--- linux-2.6.19.orig/fs/xfs/linux-2.6/xfs_fs_subr.c 2006-10-03 23:22:36.000000000 +1000
+++ linux-2.6.19/fs/xfs/linux-2.6/xfs_fs_subr.c 2007-01-17 01:24:51.771273750 +1100
@@ -32,7 +32,8 @@ fs_tosspages(
struct inode *ip = vn_to_inode(vp);
if (VN_CACHED(vp))
- truncate_inode_pages(ip->i_mapping, first);
+ truncate_unmap_inode_pages_range(ip->i_mapping,
+ first, last, 1);
}
void
@@ -49,7 +50,8 @@ fs_flushinval_pages(
if (VN_TRUNC(vp))
VUNTRUNCATE(vp);
filemap_write_and_wait(ip->i_mapping);
- truncate_inode_pages(ip->i_mapping, first);
+ truncate_unmap_inode_pages_range(ip->i_mapping,
+ first, last, 1);
}
}
Index: linux-2.6.19/include/linux/mm.h
===================================================================
--- linux-2.6.19.orig/include/linux/mm.h 2007-01-17 01:21:16.017790000 +1100
+++ linux-2.6.19/include/linux/mm.h 2007-01-17 01:24:51.775274000 +1100
@@ -1058,6 +1058,8 @@ extern unsigned long page_unuse(struct p
extern void truncate_inode_pages(struct address_space *, loff_t);
extern void truncate_inode_pages_range(struct address_space *,
loff_t lstart, loff_t lend);
+extern void truncate_unmap_inode_pages_range(struct address_space *,
+ loff_t lstart, loff_t lend, int unmap);
/* generic vm_area_ops exported for stackable file systems */
extern struct page *filemap_nopage(struct vm_area_struct *, unsigned long, int *);
Index: linux-2.6.19/mm/truncate.c
===================================================================
--- linux-2.6.19.orig/mm/truncate.c 2007-01-17 01:21:23.074231000 +1100
+++ linux-2.6.19/mm/truncate.c 2007-01-17 01:24:51.779274250 +1100
@@ -59,7 +59,7 @@ void cancel_dirty_page(struct page *page
WARN_ON(++warncount < 5);
}
-
+
if (TestClearPageDirty(page)) {
struct address_space *mapping = page->mapping;
if (mapping && mapping_cap_account_dirty(mapping)) {
@@ -122,16 +122,34 @@ invalidate_complete_page(struct address_
return ret;
}
+/*
+ * This is a helper for truncate_unmap_inode_page. Unmap the page we
+ * are passed. Page must be locked by the caller.
+ */
+static void
+unmap_single_page(struct address_space *mapping, struct page *page)
+{
+ BUG_ON(!PageLocked(page));
+ while (page_mapped(page)) {
+ unmap_mapping_range(mapping,
+ (loff_t)page->index << PAGE_CACHE_SHIFT,
+ PAGE_CACHE_SIZE, 0);
+ }
+}
+
/**
- * truncate_inode_pages - truncate range of pages specified by start and
+ * truncate_unmap_inode_pages_range - truncate range of pages specified by
+ * start and end byte offsets and optionally unmap them first.
* end byte offsets
* @mapping: mapping to truncate
* @lstart: offset from which to truncate
* @lend: offset to which to truncate
+ * @unmap: unmap whole truncated pages if non-zero
*
* Truncate the page cache, removing the pages that are between
* specified offsets (and zeroing out partial page
- * (if lstart is not page aligned)).
+ * (if lstart is not page aligned)). If specified, unmap the pages
+ * before they are removed.
*
* Truncate takes two passes - the first pass is nonblocking. It will not
* block on page locks and it will not block on writeback. The second pass
@@ -146,8 +164,8 @@ invalidate_complete_page(struct address_
* mapping is large, it is probably the case that the final pages are the most
* recently touched, and freeing happens in ascending file offset order.
*/
-void truncate_inode_pages_range(struct address_space *mapping,
- loff_t lstart, loff_t lend)
+void truncate_unmap_inode_pages_range(struct address_space *mapping,
+ loff_t lstart, loff_t lend, int unmap)
{
const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
pgoff_t end;
@@ -162,6 +180,14 @@ void truncate_inode_pages_range(struct a
BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
end = (lend >> PAGE_CACHE_SHIFT);
+ /*
+ * if unmapping, do a range unmap up front to minimise the
+ * overhead of unmapping the pages
+ */
+ if (unmap) {
+ unmap_mapping_range(mapping, (loff_t)start << PAGE_CACHE_SHIFT,
+ (loff_t)end << PAGE_CACHE_SHIFT, 0);
+ }
pagevec_init(&pvec, 0);
next = start;
while (next <= end &&
@@ -184,6 +210,8 @@ void truncate_inode_pages_range(struct a
unlock_page(page);
continue;
}
+ if (unmap)
+ unmap_single_page(mapping, page);
truncate_complete_page(mapping, page);
unlock_page(page);
}
@@ -195,6 +223,8 @@ void truncate_inode_pages_range(struct a
struct page *page = find_lock_page(mapping, start - 1);
if (page) {
wait_on_page_writeback(page);
+ if (unmap)
+ unmap_single_page(mapping, page);
truncate_partial_page(page, partial);
unlock_page(page);
page_cache_release(page);
@@ -224,12 +254,30 @@ void truncate_inode_pages_range(struct a
if (page->index > next)
next = page->index;
next++;
+ if (unmap)
+ unmap_single_page(mapping, page);
truncate_complete_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
}
}
+EXPORT_SYMBOL(truncate_unmap_inode_pages_range);
+
+/**
+ * truncate_inode_pages_range - truncate range of pages specified by start and
+ * end byte offsets
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ * @lend: offset to which to truncate
+ *
+ * Called under (and serialised by) inode->i_mutex.
+ */
+void truncate_inode_pages_range(struct address_space *mapping,
+ loff_t lstart, loff_t lend)
+{
+ truncate_unmap_inode_pages_range(mapping, lstart, lend, 0);
+}
EXPORT_SYMBOL(truncate_inode_pages_range);
/**
@@ -241,7 +289,7 @@ EXPORT_SYMBOL(truncate_inode_pages_range
*/
void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
{
- truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
+ truncate_unmap_inode_pages_range(mapping, lstart, (loff_t)-1, 0);
}
EXPORT_SYMBOL(truncate_inode_pages);
-
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