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authorJan Kara <jack@suse.cz>2017-01-27 14:35:38 -0500
committerBen Hutchings <ben@decadent.org.uk>2017-06-05 21:13:45 +0100
commit56809722764c76f0383dc3be872bca1cfa59c8d9 (patch)
treee5a3e0732878ddb04f139fc4cdfd53d494230fc4
parentec7d1dbf6dda4f536dbafa966fb111b653948f07 (diff)
ext4: fix data corruption in data=journal mode
commit 3b136499e906460919f0d21a49db1aaccf0ae963 upstream. ext4_journalled_write_end() did not propely handle all the cases when generic_perform_write() did not copy all the data into the target page and could mark buffers with uninitialized contents as uptodate and dirty leading to possible data corruption (which would be quickly fixed by generic_perform_write() retrying the write but still). Fix the problem by carefully handling the case when the page that is written to is not uptodate. Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--fs/ext4/inode.c27
1 files changed, 16 insertions, 11 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7e22e7636834..f881e3484481 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1073,7 +1073,9 @@ static int ext4_writeback_write_end(struct file *file,
* set the buffer to be dirty, since in data=journalled mode we need
* to call ext4_handle_dirty_metadata() instead.
*/
-static void zero_new_buffers(struct page *page, unsigned from, unsigned to)
+static void ext4_journalled_zero_new_buffers(handle_t *handle,
+ struct page *page,
+ unsigned from, unsigned to)
{
unsigned int block_start = 0, block_end;
struct buffer_head *head, *bh;
@@ -1090,7 +1092,7 @@ static void zero_new_buffers(struct page *page, unsigned from, unsigned to)
size = min(to, block_end) - start;
zero_user(page, start, size);
- set_buffer_uptodate(bh);
+ write_end_fn(handle, bh);
}
clear_buffer_new(bh);
}
@@ -1118,16 +1120,19 @@ static int ext4_journalled_write_end(struct file *file,
BUG_ON(!ext4_handle_valid(handle));
- if (copied < len) {
- if (!PageUptodate(page))
- copied = 0;
- zero_new_buffers(page, from+copied, to);
+ if (unlikely(copied < len) && !PageUptodate(page)) {
+ copied = 0;
+ ext4_journalled_zero_new_buffers(handle, page, from, to);
+ } else {
+ if (unlikely(copied < len))
+ ext4_journalled_zero_new_buffers(handle, page,
+ from + copied, to);
+ ret = walk_page_buffers(handle, page_buffers(page), from,
+ from + copied, &partial,
+ write_end_fn);
+ if (!partial)
+ SetPageUptodate(page);
}
-
- ret = walk_page_buffers(handle, page_buffers(page), from,
- to, &partial, write_end_fn);
- if (!partial)
- SetPageUptodate(page);
new_i_size = pos + copied;
if (new_i_size > inode->i_size)
i_size_write(inode, pos+copied);