New for 5.3:

- Only mark inode dirty at the end of writing to a file (instead of once
   for every page written).
 - Fix for an accounting error in the page_done callback.
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Merge tag 'iomap-5.3-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull iomap updates from Darrick Wong:
 "There are a few fixes for gfs2 but otherwise it's pretty quiet so far.

   - Only mark inode dirty at the end of writing to a file (instead of
     once for every page written).

   - Fix for an accounting error in the page_done callback"

* tag 'iomap-5.3-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  iomap: fix page_done callback for short writes
  fs: fold __generic_write_end back into generic_write_end
  iomap: don't mark the inode dirty in iomap_write_end

fs/buffer.c

@@ -2086,38 +2086,6 @@ int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
 }
 EXPORT_SYMBOL(block_write_begin);
 
-void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
-		struct page *page)
-{
-	loff_t old_size = inode->i_size;
-	bool i_size_changed = false;
-
-	/*
-	 * No need to use i_size_read() here, the i_size cannot change under us
-	 * because we hold i_rwsem.
-	 *
-	 * But it's important to update i_size while still holding page lock:
-	 * page writeout could otherwise come in and zero beyond i_size.
-	 */
-	if (pos + copied > inode->i_size) {
-		i_size_write(inode, pos + copied);
-		i_size_changed = true;
-	}
-
-	unlock_page(page);
-
-	if (old_size < pos)
-		pagecache_isize_extended(inode, old_size, pos);
-	/*
-	 * Don't mark the inode dirty under page lock. First, it unnecessarily
-	 * makes the holding time of page lock longer. Second, it forces lock
-	 * ordering of page lock and transaction start for journaling
-	 * filesystems.
-	 */
-	if (i_size_changed)
-		mark_inode_dirty(inode);
-}
-
 int block_write_end(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned copied,
 			struct page *page, void *fsdata)
@@ -2158,9 +2126,37 @@ int generic_write_end(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned copied,
 			struct page *page, void *fsdata)
 {
+	struct inode *inode = mapping->host;
+	loff_t old_size = inode->i_size;
+	bool i_size_changed = false;
+
 	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
-	__generic_write_end(mapping->host, pos, copied, page);
+
+	/*
+	 * No need to use i_size_read() here, the i_size cannot change under us
+	 * because we hold i_rwsem.
+	 *
+	 * But it's important to update i_size while still holding page lock:
+	 * page writeout could otherwise come in and zero beyond i_size.
+	 */
+	if (pos + copied > inode->i_size) {
+		i_size_write(inode, pos + copied);
+		i_size_changed = true;
+	}
+
+	unlock_page(page);
 	put_page(page);
+
+	if (old_size < pos)
+		pagecache_isize_extended(inode, old_size, pos);
+	/*
+	 * Don't mark the inode dirty under page lock. First, it unnecessarily
+	 * makes the holding time of page lock longer. Second, it forces lock
+	 * ordering of page lock and transaction start for journaling
+	 * filesystems.
+	 */
+	if (i_size_changed)
+		mark_inode_dirty(inode);
 	return copied;
 }
 EXPORT_SYMBOL(generic_write_end);

fs/gfs2/bmap.c

@@ -1182,6 +1182,8 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 
 	if (ip->i_qadata && ip->i_qadata->qa_qd_num)
 		gfs2_quota_unlock(ip);
+	if (iomap->flags & IOMAP_F_SIZE_CHANGED)
+		mark_inode_dirty(inode);
 	gfs2_write_unlock(inode);
 
 out:

fs/internal.h

@@ -40,8 +40,6 @@ static inline int __sync_blockdev(struct block_device *bdev, int wait)
 extern void guard_bio_eod(int rw, struct bio *bio);
 extern int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
 		get_block_t *get_block, struct iomap *iomap);
-void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
-		struct page *page);
 
 /*
  * char_dev.c

fs/iomap.c

@@ -777,6 +777,7 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
 		unsigned copied, struct page *page, struct iomap *iomap)
 {
 	const struct iomap_page_ops *page_ops = iomap->page_ops;
+	loff_t old_size = inode->i_size;
 	int ret;
 
 	if (iomap->type == IOMAP_INLINE) {
@@ -788,9 +789,21 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
 		ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
 	}
 
-	__generic_write_end(inode, pos, ret, page);
+	/*
+	 * Update the in-memory inode size after copying the data into the page
+	 * cache.  It's up to the file system to write the updated size to disk,
+	 * preferably after I/O completion so that no stale data is exposed.
+	 */
+	if (pos + ret > old_size) {
+		i_size_write(inode, pos + ret);
+		iomap->flags |= IOMAP_F_SIZE_CHANGED;
+	}
+	unlock_page(page);
+
+	if (old_size < pos)
+		pagecache_isize_extended(inode, old_size, pos);
 	if (page_ops && page_ops->page_done)
-		page_ops->page_done(inode, pos, copied, page, iomap);
+		page_ops->page_done(inode, pos, ret, page, iomap);
 	put_page(page);
 
 	if (ret < len)

include/linux/iomap.h

@@ -35,6 +35,7 @@ struct vm_fault;
 #define IOMAP_F_NEW		0x01	/* blocks have been newly allocated */
 #define IOMAP_F_DIRTY		0x02	/* uncommitted metadata */
 #define IOMAP_F_BUFFER_HEAD	0x04	/* file system requires buffer heads */
+#define IOMAP_F_SIZE_CHANGED	0x08	/* file size has changed */
 
 /*
  * Flags that only need to be reported for IOMAP_REPORT requests: