In the bio completion routine, we should not be setting
PageUptodate at all -- it's set at sys_write() time, and is
unaffected by success/failure of the write to disk.
This can cause a page corruption bug when
block size < page size
if we have only written a single block -- we might end up
setting the entire PageUptodate, which will cause subsequent
reads to get bad data.
This commit also fixes ext4_end_bio() to set AS_EIO in the
page->mapping->flags on error, which was left out by
mistake.
Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx>
Reported-by: Jim Meyering <jim@xxxxxxxxxxxx>
Reported-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Mingming Cao <cmm@xxxxxxxxxx>
---
Changlog since v1:
- Added commit message text about setting AS_EIO for the
page on error.
- Continue to loop over all BHs in a page and emit unique
errors for each of them.
---
fs/ext4/page-io.c | 22 ++++------------------
1 files changed, 4 insertions(+), 18 deletions(-)
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index b6dbd05..fb681cf 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -203,11 +203,12 @@ static void ext4_end_bio(struct bio *bio, int error)
for (i = 0; i < io_end->num_io_pages; i++) {
struct page *page = io_end->pages[i]->p_page;
struct buffer_head *bh, *head;
- int partial_write = 0;
head = page_buffers(page);
- if (error)
+ if (error) {
SetPageError(page);
+ set_bit(AS_EIO, &page->mapping->flags);
+ }
BUG_ON(!head);
if (head->b_size != PAGE_CACHE_SIZE) {
loff_t offset;
@@ -220,29 +221,14 @@ static void ext4_end_bio(struct bio *bio, int error)
(offset+bh->b_size <= io_end_offset)) {
if (error)
buffer_io_error(bh);
-
}
- if (buffer_delay(bh))
- partial_write = 1;
- else if (!buffer_mapped(bh))
+ if (!buffer_mapped(bh))
clear_buffer_dirty(bh);
- else if (buffer_dirty(bh))
- partial_write = 1;
offset += bh->b_size;
bh = bh->b_this_page;
} while (bh != head);
}
- /*
- * If this is a partial write which happened to make
- * all buffers uptodate then we can optimize away a
- * bogus readpage() for the next read(). Here we
- * 'discover' whether the page went uptodate as a
- * result of this (potentially partial) write.
- */
- if (!partial_write)
- SetPageUptodate(page);
-
put_io_page(io_end->pages[i]);
}
io_end->num_io_pages = 0;
--
1.7.3.1
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
