btrfs: set EXTENT_NORESERVE bits side btrfs_dirty_pages()

Set the extent bits EXTENT_NORESERVE inside btrfs_dirty_pages() as
opposed to calling set_extent_bits again later.

Fold check for written length within the function.

Note: EXTENT_NORESERVE is set before unlocking extents.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -3112,7 +3112,7 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 int btrfs_release_file(struct inode *inode, struct file *file);
 int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
 		      size_t num_pages, loff_t pos, size_t write_bytes,
-		      struct extent_state **cached);
+		      struct extent_state **cached, bool noreserve);
 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end);
 int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
 			   size_t *write_bytes);

fs/btrfs/file.c

@@ -462,7 +462,7 @@ static void btrfs_drop_pages(struct page **pages, size_t num_pages)
  */
 int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
 		      size_t num_pages, loff_t pos, size_t write_bytes,
-		      struct extent_state **cached)
+		      struct extent_state **cached, bool noreserve)
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	int err = 0;
@@ -474,6 +474,12 @@ int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
 	loff_t isize = i_size_read(&inode->vfs_inode);
 	unsigned int extra_bits = 0;
 
+	if (write_bytes == 0)
+		return 0;
+
+	if (noreserve)
+		extra_bits |= EXTENT_NORESERVE;
+
 	start_pos = round_down(pos, fs_info->sectorsize);
 	num_bytes = round_up(write_bytes + pos - start_pos,
 			     fs_info->sectorsize);
@@ -1720,10 +1726,9 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 		release_bytes = round_up(copied + sector_offset,
 					fs_info->sectorsize);
 
-		if (copied > 0)
-			ret = btrfs_dirty_pages(BTRFS_I(inode), pages,
-						dirty_pages, pos, copied,
-						&cached_state);
+		ret = btrfs_dirty_pages(BTRFS_I(inode), pages,
+					dirty_pages, pos, copied,
+					&cached_state, only_release_metadata);
 
 		/*
 		 * If we have not locked the extent range, because the range's
@@ -1748,17 +1753,6 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 		if (only_release_metadata)
 			btrfs_check_nocow_unlock(BTRFS_I(inode));
 
-		if (only_release_metadata && copied > 0) {
-			lockstart = round_down(pos,
-					       fs_info->sectorsize);
-			lockend = round_up(pos + copied,
-					   fs_info->sectorsize) - 1;
-
-			set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
-				       lockend, EXTENT_NORESERVE, NULL,
-				       NULL, GFP_NOFS);
-		}
-
 		btrfs_drop_pages(pages, num_pages);
 
 		cond_resched();

fs/btrfs/free-space-cache.c

@@ -1332,7 +1332,7 @@ static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 	/* Everything is written out, now we dirty the pages in the file. */
 	ret = btrfs_dirty_pages(BTRFS_I(inode), io_ctl->pages,
 				io_ctl->num_pages, 0, i_size_read(inode),
-				&cached_state);
+				&cached_state, false);
 	if (ret)
 		goto out_nospc;