diff options
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 56 |
1 files changed, 21 insertions, 35 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 8332c77b1bd..d1060b8d3cd 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -327,7 +327,7 @@ EXPORT_SYMBOL(sync_page_range); * @pos: beginning offset in pages to write * @count: number of bytes to write * - * Note: Holding i_mutex across sync_page_range_nolock is not a good idea + * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea * as it forces O_SYNC writers to different parts of the same file * to be serialised right until io completion. */ @@ -606,26 +606,6 @@ struct page * find_get_page(struct address_space *mapping, unsigned long offset) EXPORT_SYMBOL(find_get_page); /** - * find_trylock_page - find and lock a page - * @mapping: the address_space to search - * @offset: the page index - * - * Same as find_get_page(), but trylock it instead of incrementing the count. - */ -struct page *find_trylock_page(struct address_space *mapping, unsigned long offset) -{ - struct page *page; - - read_lock_irq(&mapping->tree_lock); - page = radix_tree_lookup(&mapping->page_tree, offset); - if (page && TestSetPageLocked(page)) - page = NULL; - read_unlock_irq(&mapping->tree_lock); - return page; -} -EXPORT_SYMBOL(find_trylock_page); - -/** * find_lock_page - locate, pin and lock a pagecache page * @mapping: the address_space to search * @offset: the page index @@ -804,7 +784,7 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, * @mapping: target address_space * @index: the page index * - * Same as grab_cache_page, but do not wait if the page is unavailable. + * Same as grab_cache_page(), but do not wait if the page is unavailable. * This is intended for speculative data generators, where the data can * be regenerated if the page couldn't be grabbed. This routine should * be safe to call while holding the lock for another page. @@ -2099,21 +2079,27 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov, /* Limit the size of the copy to the caller's write size */ bytes = min(bytes, count); - /* - * Limit the size of the copy to that of the current segment, - * because fault_in_pages_readable() doesn't know how to walk - * segments. - */ - bytes = min(bytes, cur_iov->iov_len - iov_base); - - /* - * Bring in the user page that we will copy from _first_. - * Otherwise there's a nasty deadlock on copying from the - * same page as we're writing to, without it being marked - * up-to-date. + /* We only need to worry about prefaulting when writes are from + * user-space. NFSd uses vfs_writev with several non-aligned + * segments in the vector, and limiting to one segment a time is + * a noticeable performance for re-write */ - fault_in_pages_readable(buf, bytes); + if (!segment_eq(get_fs(), KERNEL_DS)) { + /* + * Limit the size of the copy to that of the current + * segment, because fault_in_pages_readable() doesn't + * know how to walk segments. + */ + bytes = min(bytes, cur_iov->iov_len - iov_base); + /* + * Bring in the user page that we will copy from + * _first_. Otherwise there's a nasty deadlock on + * copying from the same page as we're writing to, + * without it being marked up-to-date. + */ + fault_in_pages_readable(buf, bytes); + } page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); if (!page) { status = -ENOMEM; |