On Thu, 12 Sep 2013 15:58:51 +0100 Sachin Prabhu <[email protected]> wrote:
> When reading a single page with cifs_readpage(), we make a call to > fscache_read_or_alloc_page() which once done, asynchronously calls > the completion function cifs_readpage_from_fscache_complete(). This > completion function unlocks the page once it has been populated from > cache. The module then attempts to unlock the page a second time in > cifs_readpage() which leads to warning messages. > > In case of a successful call to fscache_read_or_alloc_page() we should skip > the second unlock_page() since this will be called by the > cifs_readpage_from_fscache_complete() once the page has been populated by > fscache. > > With the modifications to cifs_readpage_worker(), we will need to re-grab the > page lock in cifs_write_begin(). > > Signed-off-by: Sachin Prabhu <[email protected]> > --- > fs/cifs/file.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index 69e8431..98e5222 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -3423,6 +3423,7 @@ static int cifs_readpage_worker(struct file *file, > struct page *page, > io_error: > kunmap(page); > page_cache_release(page); > + unlock_page(page); > > read_complete: > return rc; > @@ -3447,8 +3448,6 @@ static int cifs_readpage(struct file *file, struct page > *page) > > rc = cifs_readpage_worker(file, page, &offset); > > - unlock_page(page); > - > free_xid(xid); > return rc; > } > @@ -3502,6 +3501,7 @@ static int cifs_write_begin(struct file *file, struct > address_space *mapping, > loff_t pos, unsigned len, unsigned flags, > struct page **pagep, void **fsdata) > { > + int oncethru = 0; > pgoff_t index = pos >> PAGE_CACHE_SHIFT; > loff_t offset = pos & (PAGE_CACHE_SIZE - 1); > loff_t page_start = pos & PAGE_MASK; > @@ -3511,6 +3511,7 @@ static int cifs_write_begin(struct file *file, struct > address_space *mapping, > > cifs_dbg(FYI, "write_begin from %lld len %d\n", (long long)pos, len); > > +start: > page = grab_cache_page_write_begin(mapping, index, flags); > if (!page) { > rc = -ENOMEM; > @@ -3552,13 +3553,16 @@ static int cifs_write_begin(struct file *file, struct > address_space *mapping, > } > } > > - if ((file->f_flags & O_ACCMODE) != O_WRONLY) { > + if ((file->f_flags & O_ACCMODE) != O_WRONLY && !oncethru) { > /* > * might as well read a page, it is fast enough. If we get > * an error, we don't need to return it. cifs_write_end will > * do a sync write instead since PG_uptodate isn't set. > */ > cifs_readpage_worker(file, page, &page_start); > + page_cache_release(page); > + oncethru = 1; > + goto start; > } else { > /* we could try using another file handle if there is one - > but how would we lock it to prevent close of that handle Looks correct. Nice catch! Reviewed-by: Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
