[PATCH v2 08/12] btrfs: make lock_and_cleanup_extent_if_need nowait compatible

[Stefan Roesch <shr@fb.com>]

This adds the nowait parameter to lock_and_cleanup_extent_if_need(). If
the nowait parameter is specified we try to lock the extent in nowait
mode.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/btrfs/file.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index a154a3cec44b..4e1745e585cb 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1440,7 +1440,7 @@ static noinline int
 lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
 				size_t num_pages, loff_t pos,
 				size_t write_bytes,
-				u64 *lockstart, u64 *lockend,
+				u64 *lockstart, u64 *lockend, bool nowait,
 				struct extent_state **cached_state)
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
@@ -1455,8 +1455,20 @@ lock_and_cleanup_extent_if_need(struct btrfs_inode *inode, struct page **pages,
 	if (start_pos < inode->vfs_inode.i_size) {
 		struct btrfs_ordered_extent *ordered;
 
-		lock_extent_bits(&inode->io_tree, start_pos, last_pos,
+		if (nowait) {
+			if (!try_lock_extent(&inode->io_tree, start_pos, last_pos)) {
+				for (i = 0; i < num_pages; i++) {
+					unlock_page(pages[i]);
+					put_page(pages[i]);
+				}
+
+				return -EAGAIN;
+			}
+		} else {
+			lock_extent_bits(&inode->io_tree, start_pos, last_pos,
 				cached_state);
+		}
+
 		ordered = btrfs_lookup_ordered_range(inode, start_pos,
 						     last_pos - start_pos + 1);
 		if (ordered &&
@@ -1755,7 +1767,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 		extents_locked = lock_and_cleanup_extent_if_need(
 				BTRFS_I(inode), pages,
 				num_pages, pos, write_bytes, &lockstart,
-				&lockend, &cached_state);
+				&lockend, false, &cached_state);
 		if (extents_locked < 0) {
 			if (extents_locked == -EAGAIN)
 				goto again;
-- 
2.30.2