[PATCH v3] btrfs: remove force argument from run_delalloc_nocow()

[PATCH v3] btrfs: remove force argument from run_delalloc_nocow()

[Goldwyn Rodrigues]

force_nocow can be calculated by btrfs_inode and does not need to be
passed as an argument.

This simplifies run_delalloc_nocow() call from btrfs_run_delalloc_range()
A new function, should_nocow() checks if the range should be nocow'd or
not. The function returns true iff either BTRFS_INODE_NODATA or
BTRFS_INODE_PREALLOC, but is not a defrag extent.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Changes since v2:
 - merge should_nocow() functionality to fix bug where nocow path was
   followed incorrectly.

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 604c2fcea051..9e1a934ecedc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1516,7 +1516,7 @@ static int fallback_to_cow(struct btrfs_inode *inode, struct page *locked_page,
 static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
 				       struct page *locked_page,
 				       const u64 start, const u64 end,
-				       int *page_started, int force,
+				       int *page_started,
 				       unsigned long *nr_written)
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
@@ -1530,6 +1530,7 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
 	u64 ino = btrfs_ino(inode);
 	bool nocow = false;
 	u64 disk_bytenr = 0;
+	const bool force = inode->flags & BTRFS_INODE_NODATACOW;
 
 	path = btrfs_alloc_path();
 	if (!path) {
@@ -1863,23 +1864,16 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
 	return ret;
 }
 
-static inline int need_force_cow(struct btrfs_inode *inode, u64 start, u64 end)
+static inline bool should_nocow(struct btrfs_inode *inode, u64 start, u64 end)
 {
-
-	if (!(inode->flags & BTRFS_INODE_NODATACOW) &&
-	    !(inode->flags & BTRFS_INODE_PREALLOC))
-		return 0;
-
-	/*
-	 * @defrag_bytes is a hint value, no spinlock held here,
-	 * if is not zero, it means the file is defragging.
-	 * Force cow if given extent needs to be defragged.
-	 */
-	if (inode->defrag_bytes &&
-	    test_range_bit(&inode->io_tree, start, end, EXTENT_DEFRAG, 0, NULL))
-		return 1;
-
-	return 0;
+	if (inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)) {
+		if (inode->defrag_bytes &&
+		    test_range_bit(&inode->io_tree, start, end, EXTENT_DEFRAG,
+				   0, NULL))
+			return false;
+		return true;
+	}
+	return false;
 }
 
 /*
@@ -1891,17 +1885,12 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page
 		struct writeback_control *wbc)
 {
 	int ret;
-	int force_cow = need_force_cow(inode, start, end);
 	const bool zoned = btrfs_is_zoned(inode->root->fs_info);
 
-	if (inode->flags & BTRFS_INODE_NODATACOW && !force_cow) {
-		ASSERT(!zoned);
-		ret = run_delalloc_nocow(inode, locked_page, start, end,
-					 page_started, 1, nr_written);
-	} else if (inode->flags & BTRFS_INODE_PREALLOC && !force_cow) {
+	if (should_nocow(inode, start, end)) {
 		ASSERT(!zoned);
 		ret = run_delalloc_nocow(inode, locked_page, start, end,
-					 page_started, 0, nr_written);
+					 page_started, nr_written);
 	} else if (!inode_can_compress(inode) ||
 		   !inode_need_compress(inode, start, end)) {
 		if (zoned)

-- 
Goldwyn

Re: [PATCH v3] btrfs: remove force argument from run_delalloc_nocow()

[David Sterba]

On Thu, Mar 04, 2021 at 09:06:25AM -0600, Goldwyn Rodrigues wrote:
> force_nocow can be calculated by btrfs_inode and does not need to be
> passed as an argument.
> 
> This simplifies run_delalloc_nocow() call from btrfs_run_delalloc_range()
> A new function, should_nocow() checks if the range should be nocow'd or
> not. The function returns true iff either BTRFS_INODE_NODATA or
> BTRFS_INODE_PREALLOC, but is not a defrag extent.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> Reviewed-by: David Sterba <dsterba@suse.com>
> Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Added to misc-next, thanks.