On Tue, 2008-07-01 at 10:54 +0000, Gary Hawco wrote:
> Ted,
>
> Thanks for your quick reply. With the newest rc8-based snapshots I am no
> longer getting segfaults, unless you wanted me to roll back to the
> rc6-based snapshots to reproduce the segfaults.
>
> Per your latest request I disabled delalloc, and voila, no more data
> corruption! Then I enabled delalloc and disabled mballoc and file
> corruption to /lib/rc/init.d/nettree returned. So delalloc is the culprit.
>
> I hope this will help figure this out.
>
Could you try the following patch? It fixes the problem of update
on-disk size too early without block allocation, the problem is
introduced unintentionally by another bug fix patch added to the patch
queue yesterday.
Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
---
fs/ext4/inode.c | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
Index: linux-2.6.26-rc8/fs/ext4/inode.c
===================================================================
--- linux-2.6.26-rc8.orig/fs/ext4/inode.c 2008-07-01 15:13:00.000000000 -0700
+++ linux-2.6.26-rc8/fs/ext4/inode.c 2008-07-01 15:34:19.000000000 -0700
@@ -1892,6 +1892,31 @@ out:
return ret;
}
+/*
+ * Check if we should update i_disksize
+ * when write to the end of file but not require block allocation
+ */
+static int ext4_da_should_update_i_disksize(struct page *page,
+ unsigned long offset)
+{
+ struct buffer_head *head, *bh;
+ unsigned int curr_off = 0;
+
+ head = page_buffers(page);
+ bh = head;
+ do {
+ unsigned int next_off = curr_off + bh->b_size;
+
+ if ((curr_off >= offset) &&
+ (!buffer_mapped || (buffer_delay(bh))) {
+ return 0;
+ }
+ curr_off = next_off;
+ } while ((bh = bh->b_this_page) != head);
+
+ return 1;
+}
+
static int ext4_da_write_end(struct file *file,
struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
@@ -1901,6 +1926,10 @@ static int ext4_da_write_end(struct file
int ret = 0, ret2;
handle_t *handle = ext4_journal_current_handle();
loff_t new_i_size;
+ unsigned long start, end;
+
+ start = pos & (PAGE_CACHE_SIZE - 1);
+ end = start + copied;
/*
* generic_write_end() will run mark_inode_dirty() if i_size
@@ -1910,8 +1939,7 @@ static int ext4_da_write_end(struct file
new_i_size = pos + copied;
if (new_i_size > EXT4_I(inode)->i_disksize)
- if (!walk_page_buffers(NULL, page_buffers(page),
- 0, len, NULL, ext4_bh_unmapped_or_delay)){
+ if (ext4_da_should_update_i_disksize(page, end))
/*
* Updating i_disksize when extending file without
* need block allocation
> Thanks again,
> Gary
>
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