Fix attached.
Shaggy/Jeff/Nick etc. do you want to review/ack it since it is late in the rc?
On Fri, Nov 21, 2008 at 2:18 PM, Steve French <smfrench@xxxxxxxxx> wrote:
> Looks like the following change to cifs_write_begin does fix it ...
> thanks Shaggy ...
>
> @@ -2062,8 +2074,10 @@ static int cifs_write_begin(struct file *file,
> struct address_space *mapping,
> {
> pgoff_t index = pos >> PAGE_CACHE_SHIFT;
> loff_t offset = pos & (PAGE_CACHE_SIZE - 1);
> + loff_t page_start = pos & PAGE_MASK;
>
> cFYI(1, ("write_begin from %lld len %d", (long long)pos, len));
> @@ -2081,13 +2095,14 @@ static int cifs_write_begin(struct file *file,
> struct address_space *mapping,
> int rc;
>
> /* might as well read a page, it is fast enough */
> - rc = cifs_readpage_worker(file, *pagep, &offset);
> + rc = cifs_readpage_worker(file, *pagep, &page_start);
>
> /* we do not need to pass errors back
> e.g. if we do not have read access to the file
> because cifs_write_end will attempt synchronous writes
> -- shaggy */
>
>
> On Fri, Nov 21, 2008 at 1:41 PM, Dave Kleikamp
> <shaggy@xxxxxxxxxxxxxxxxxx> wrote:
>> On Fri, 2008-11-21 at 13:13 -0600, Steve French wrote:
>>> Looks like this section of code is wrong in cifs_write_begin:
>>>
>>> if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
>>> int rc;
>>>
>>> /* might as well read a page, it is fast enough */
>>> rc = cifs_readpage_worker(file, *pagep, &offset);
>>>
>>> /* we do not need to pass errors back
>>> e.g. if we do not have read access to the file
>>> because cifs_write_end will attempt synchronous writes
>>> -- shaggy */
>>>
>>>
>>> We see a case in which a write begins at offset 0x2e42f but the range
>>> immediately before it is unitialized in write_begin
>>>
>>> shouldn't we be doing a read of the whole page?
>>
>> What cifs_write_begin() passes in as offset is completely wrong. It
>> should be the file offset of the beginning of the page rather than some
>> offset within the page.
>> --
>> David Kleikamp
>> IBM Linux Technology Center
>>
>>
>
>
>
> --
> Thanks,
>
> Steve
>
--
Thanks,
Steve
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index b691b89..726d437 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2061,7 +2061,7 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
struct page **pagep, void **fsdata)
{
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- loff_t offset = pos & (PAGE_CACHE_SIZE - 1);
+ loff_t offset_of_page_start = pos & PAGE_MASK;
cFYI(1, ("write_begin from %lld len %d", (long long)pos, len));
@@ -2081,7 +2081,7 @@ static int cifs_write_begin(struct file *file, struct address_space *mapping,
int rc;
/* might as well read a page, it is fast enough */
- rc = cifs_readpage_worker(file, *pagep, &offset);
+ rc = cifs_readpage_worker(file, *pagep, &offset_of_page_start);
/* we do not need to pass errors back
e.g. if we do not have read access to the file
