Merge tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayto...

[karo-tx-linux.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index d7a30aefee0d413c9d0726047b91c95f4bf8073f..3247b4208034723c82ad05f0ca4cc880cbdc91d9 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -386,6 +386,38 @@ int filemap_flush(struct address_space *mapping)
 }
 EXPORT_SYMBOL(filemap_flush);
 
+/**
+ * filemap_range_has_page - check if a page exists in range.
+ * @mapping:           address space within which to check
+ * @start_byte:        offset in bytes where the range starts
+ * @end_byte:          offset in bytes where the range ends (inclusive)
+ *
+ * Find at least one page in the range supplied, usually used to check if
+ * direct writing in this range will trigger a writeback.
+ */
+bool filemap_range_has_page(struct address_space *mapping,
+                          loff_t start_byte, loff_t end_byte)
+{
+       pgoff_t index = start_byte >> PAGE_SHIFT;
+       pgoff_t end = end_byte >> PAGE_SHIFT;
+       struct pagevec pvec;
+       bool ret;
+
+       if (end_byte < start_byte)
+               return false;
+
+       if (mapping->nrpages == 0)
+               return false;
+
+       pagevec_init(&pvec, 0);
+       if (!pagevec_lookup(&pvec, mapping, index, 1))
+               return false;
+       ret = (pvec.pages[0]->index <= end);
+       pagevec_release(&pvec);
+       return ret;
+}
+EXPORT_SYMBOL(filemap_range_has_page);
+
 static void __filemap_fdatawait_range(struct address_space *mapping,
                                     loff_t start_byte, loff_t end_byte)
 {
@@ -860,10 +892,10 @@ struct wait_page_key {
 struct wait_page_queue {
        struct page *page;
        int bit_nr;
-       wait_queue_t wait;
+       wait_queue_entry_t wait;
 };
 
-static int wake_page_function(wait_queue_t *wait, unsigned mode, int sync, void *arg)
+static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
 {
        struct wait_page_key *key = arg;
        struct wait_page_queue *wait_page
@@ -926,7 +958,7 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
                struct page *page, int bit_nr, int state, bool lock)
 {
        struct wait_page_queue wait_page;
-       wait_queue_t *wait = &wait_page.wait;
+       wait_queue_entry_t *wait = &wait_page.wait;
        int ret = 0;
 
        init_wait(wait);
@@ -937,9 +969,9 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
        for (;;) {
                spin_lock_irq(&q->lock);
 
-               if (likely(list_empty(&wait->task_list))) {
+               if (likely(list_empty(&wait->entry))) {
                        if (lock)
-                               __add_wait_queue_tail_exclusive(q, wait);
+                               __add_wait_queue_entry_tail_exclusive(q, wait);
                        else
                                __add_wait_queue(q, wait);
                        SetPageWaiters(page);
@@ -999,7 +1031,7 @@ int wait_on_page_bit_killable(struct page *page, int bit_nr)
  *
  * Add an arbitrary @waiter to the wait queue for the nominated @page.
  */
-void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
+void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter)
 {
        wait_queue_head_t *q = page_waitqueue(page);
        unsigned long flags;
@@ -2130,10 +2162,17 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                loff_t size;
 
                size = i_size_read(inode);
-               retval = filemap_write_and_wait_range(mapping, iocb->ki_pos,
-                                       iocb->ki_pos + count - 1);
-               if (retval < 0)
-                       goto out;
+               if (iocb->ki_flags & IOCB_NOWAIT) {
+                       if (filemap_range_has_page(mapping, iocb->ki_pos,
+                                                  iocb->ki_pos + count - 1))
+                               return -EAGAIN;
+               } else {
+                       retval = filemap_write_and_wait_range(mapping,
+                                               iocb->ki_pos,
+                                               iocb->ki_pos + count - 1);
+                       if (retval < 0)
+                               goto out;
+               }
 
                file_accessed(file);
 
@@ -2318,7 +2357,7 @@ int filemap_fault(struct vm_fault *vmf)
                /* No page in the page cache at all */
                do_sync_mmap_readahead(vmf->vma, ra, file, offset);
                count_vm_event(PGMAJFAULT);
-               mem_cgroup_count_vm_event(vmf->vma->vm_mm, PGMAJFAULT);
+               count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
                ret = VM_FAULT_MAJOR;
 retry_find:
                page = find_get_page(mapping, offset);
@@ -2734,6 +2773,9 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
 
        pos = iocb->ki_pos;
 
+       if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
+               return -EINVAL;
+
        if (limit != RLIM_INFINITY) {
                if (iocb->ki_pos >= limit) {
                        send_sig(SIGXFSZ, current, 0);
@@ -2802,9 +2844,17 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
        write_len = iov_iter_count(from);
        end = (pos + write_len - 1) >> PAGE_SHIFT;
 
-       written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
-       if (written)
-               goto out;
+       if (iocb->ki_flags & IOCB_NOWAIT) {
+               /* If there are pages to writeback, return */
+               if (filemap_range_has_page(inode->i_mapping, pos,
+                                          pos + iov_iter_count(from)))
+                       return -EAGAIN;
+       } else {
+               written = filemap_write_and_wait_range(mapping, pos,
+                                                       pos + write_len - 1);
+               if (written)
+                       goto out;
+       }
 
        /*
         * After a write we want buffered reads to be sure to go to disk to get