From: Zygo Blaxell <bees@furryterror.org>
Date: Sun, 29 Jun 2025 20:30:03 +0000 (-0400)
Subject: tempfile: clear FS_NOCOW_FL while setting FS_COMPR_FL
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4039ef229e5fcbfa34dfee2fd601073e5005a5b7;p=bees

tempfile: clear FS_NOCOW_FL while setting FS_COMPR_FL

FS_NOCOW_FL can be inherited from the subvol root directory, and it
conflicts with FS_COMPR_FL.

We can only dedupe when FS_NOCOW_FL is the same on src and dst, which
means we can only dedupe when FS_NOCOW_FL is clear, so we should clear
FS_NOCOW_FL on the temporary files we create for dedupe.

Fixes: https://github.com/Zygo/bees/issues/314
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
---

diff --git a/src/bees.cc b/src/bees.cc
index bf58d257..e13b035d 100644
--- a/src/bees.cc
+++ b/src/bees.cc
@@ -547,6 +547,10 @@ BeesTempFile::BeesTempFile(shared_ptr<BeesContext> ctx) :
 	BEESTRACE("Getting FS_COMPR_FL on m_fd " << name_fd(m_fd));
 	int flags = ioctl_iflags_get(m_fd);
 	flags |= FS_COMPR_FL;
+
+	// Clear NOCOW because it conflicts with COMPR, and NOCOW could be set on the root subvol
+	flags &= FS_NOCOW_FL;
+
 	BEESTRACE("Setting FS_COMPR_FL on m_fd " << name_fd(m_fd) << " flags " << to_hex(flags));
 	ioctl_iflags_set(m_fd, flags);