[PATCH v2] btrfs: cleanup extent locking sequence

[PATCH v2] btrfs: cleanup extent locking sequence

[Goldwyn Rodrigues]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

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>

---
Changes since v1:
	fixed using extents_locked vs ret for error checks. Declared
	closer to use.

 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 f6c6754cf52d..aae589e0915a 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);
 
@@ -1670,7 +1670,6 @@ 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
@@ -1683,16 +1682,15 @@ 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);
@@ -1754,7 +1752,7 @@ 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);
-- 
2.14.2

Re: [PATCH v2] btrfs: cleanup extent locking sequence

[David Sterba]

On Mon, Oct 16, 2017 at 05:43:21AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> 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>