From 79f015f216539dfdf0d3ef0b3bbb9dc7754364cd Mon Sep 17 00:00:00 2001
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
Date: Mon, 16 Oct 2017 05:43:21 -0500
Patch-mainline: v4.15
Git-commit: 79f015f216539dfdf0d3ef0b3bbb9dc7754364cd
References: dependency for bsc#1031392
Subject: [PATCH] btrfs: cleanup extent locking sequence

Code cleanup for better understanding:
Variable needs_unlock to be called extent_locked to show state as
opposed to action. Changed the type to int, to reduce code in the
critical path.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/file.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index d3c1725f03e4..4de174b664ff 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1590,7 +1590,6 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 	int ret = 0;
 	bool only_release_metadata = false;
 	bool force_page_uptodate = false;
-	bool need_unlock;
 
 	nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
 			PAGE_SIZE / (sizeof(struct page *)));
@@ -1613,6 +1612,7 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 		size_t copied;
 		size_t dirty_sectors;
 		size_t num_sectors;
+		int extents_locked;
 
 		WARN_ON(num_pages > nrptrs);
 
@@ -1669,7 +1669,6 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 		}
 
 		release_bytes = reserve_bytes;
-		need_unlock = false;
 again:
 		/*
 		 * This is going to setup the pages array with the number of
@@ -1682,16 +1681,15 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 		if (ret)
 			break;
 
-		ret = lock_and_cleanup_extent_if_need(BTRFS_I(inode), pages,
+		extents_locked = lock_and_cleanup_extent_if_need(
+				BTRFS_I(inode), pages,
 				num_pages, pos, write_bytes, &lockstart,
 				&lockend, &cached_state);
-		if (ret < 0) {
-			if (ret == -EAGAIN)
+		if (extents_locked < 0) {
+			if (extents_locked == -EAGAIN)
 				goto again;
+			ret = extents_locked;
 			break;
-		} else if (ret > 0) {
-			need_unlock = true;
-			ret = 0;
 		}
 
 		copied = btrfs_copy_from_user(pos, write_bytes, pages, i);
@@ -1756,7 +1754,7 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 		if (copied > 0)
 			ret = btrfs_dirty_pages(inode, pages, dirty_pages,
 						pos, copied, NULL);
-		if (need_unlock)
+		if (extents_locked)
 			unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 					     lockstart, lockend, &cached_state,
 					     GFP_NOFS);
-- 
2.19.0