Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[mirror_ubuntu-bionic-kernel.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 9d21afd692b92ae243c1f404ce788048e1c4d768..db250d0e05655a2e4b72e4f7a7834964a641c86d 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -909,13 +909,33 @@ static void wake_up_page_bit(struct page *page, int bit_nr)
        wait_queue_head_t *q = page_waitqueue(page);
        struct wait_page_key key;
        unsigned long flags;
+       wait_queue_entry_t bookmark;
 
        key.page = page;
        key.bit_nr = bit_nr;
        key.page_match = 0;
 
+       bookmark.flags = 0;
+       bookmark.private = NULL;
+       bookmark.func = NULL;
+       INIT_LIST_HEAD(&bookmark.entry);
+
        spin_lock_irqsave(&q->lock, flags);
-       __wake_up_locked_key(q, TASK_NORMAL, &key);
+       __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
+
+       while (bookmark.flags & WQ_FLAG_BOOKMARK) {
+               /*
+                * Take a breather from holding the lock,
+                * allow pages that finish wake up asynchronously
+                * to acquire the lock and remove themselves
+                * from wait queue
+                */
+               spin_unlock_irqrestore(&q->lock, flags);
+               cpu_relax();
+               spin_lock_irqsave(&q->lock, flags);
+               __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
+       }
+
        /*
         * It is possible for other pages to have collided on the waitqueue
         * hash, so in that case check for a page match. That prevents a long-
@@ -1897,9 +1917,8 @@ static void shrink_readahead_size_eio(struct file *filp,
 }
 
 /**
- * do_generic_file_read - generic file read routine
- * @filp:      the file to read
- * @ppos:      current file position
+ * generic_file_buffered_read - generic file read routine
+ * @iocb:      the iocb to read
  * @iter:      data destination
  * @written:   already copied
  *
@@ -1909,12 +1928,14 @@ static void shrink_readahead_size_eio(struct file *filp,
  * This is really ugly. But the goto's actually try to clarify some
  * of the logic when it comes to error handling etc.
  */
-static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
+static ssize_t generic_file_buffered_read(struct kiocb *iocb,
                struct iov_iter *iter, ssize_t written)
 {
+       struct file *filp = iocb->ki_filp;
        struct address_space *mapping = filp->f_mapping;
        struct inode *inode = mapping->host;
        struct file_ra_state *ra = &filp->f_ra;
+       loff_t *ppos = &iocb->ki_pos;
        pgoff_t index;
        pgoff_t last_index;
        pgoff_t prev_index;
@@ -1947,6 +1968,8 @@ find_page:
 
                page = find_get_page(mapping, index);
                if (!page) {
+                       if (iocb->ki_flags & IOCB_NOWAIT)
+                               goto would_block;
                        page_cache_sync_readahead(mapping,
                                        ra, filp,
                                        index, last_index - index);
@@ -1960,6 +1983,11 @@ find_page:
                                        index, last_index - index);
                }
                if (!PageUptodate(page)) {
+                       if (iocb->ki_flags & IOCB_NOWAIT) {
+                               put_page(page);
+                               goto would_block;
+                       }
+
                        /*
                         * See comment in do_read_cache_page on why
                         * wait_on_page_locked is used to avoid unnecessarily
@@ -2141,6 +2169,8 @@ no_cached_page:
                goto readpage;
        }
 
+would_block:
+       error = -EAGAIN;
 out:
        ra->prev_pos = prev_index;
        ra->prev_pos <<= PAGE_SHIFT;
@@ -2162,14 +2192,14 @@ out:
 ssize_t
 generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 {
-       struct file *file = iocb->ki_filp;
-       ssize_t retval = 0;
        size_t count = iov_iter_count(iter);
+       ssize_t retval = 0;
 
        if (!count)
                goto out; /* skip atime */
 
        if (iocb->ki_flags & IOCB_DIRECT) {
+               struct file *file = iocb->ki_filp;
                struct address_space *mapping = file->f_mapping;
                struct inode *inode = mapping->host;
                loff_t size;
@@ -2210,7 +2240,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                        goto out;
        }
 
-       retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval);
+       retval = generic_file_buffered_read(iocb, iter, retval);
 out:
        return retval;
 }
@@ -2896,9 +2926,15 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
         * we're writing.  Either one is a pretty crazy thing to do,
         * so we don't support it 100%.  If this invalidation
         * fails, tough, the write still worked...
+        *
+        * Most of the time we do not need this since dio_complete() will do
+        * the invalidation for us. However there are some file systems that
+        * do not end up with dio_complete() being called, so let's not break
+        * them by removing it completely
         */
-       invalidate_inode_pages2_range(mapping,
-                               pos >> PAGE_SHIFT, end);
+       if (mapping->nrpages)
+               invalidate_inode_pages2_range(mapping,
+                                       pos >> PAGE_SHIFT, end);
 
        if (written > 0) {
                pos += written;