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(). The problem was first noticed when testing new fscache patches for cifs. https://bugzilla.redhat.com/show_bug.cgi?id=1005737 Signed-off-by: Sachin Prabhu <sprabhu@xxxxxxxxxx> --- 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 e47c379..7b5d0cb 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -3424,6 +3424,7 @@ static int cifs_readpage_worker(struct file *file, struct page *page, io_error: kunmap(page); + unlock_page(page); read_complete: return rc; @@ -3448,8 +3449,6 @@ 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; } @@ -3503,6 +3502,7 @@ 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; @@ -3512,6 +3512,7 @@ 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; @@ -3553,13 +3554,16 @@ 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 -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
