From 62520bb7b420c760fed8d690bd667a12a1a4abed Mon Sep 17 00:00:00 2001
From: greatroar <61184462+greatroar@users.noreply.github.com>
Date: Wed, 7 Dec 2022 09:13:19 +0100
Subject: [PATCH 1/2] sftp: Fix ENOSPC check

We now check for space that is not reserved for the root user on the
remote, and the check is no longer in a defer block because it wouldn't
fire. Some change in the surrounding code may have led the deferred
function to capture the wrong err variable.

Fixes #3336.
---
 internal/backend/sftp/sftp.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/internal/backend/sftp/sftp.go b/internal/backend/sftp/sftp.go
index 417b6681a..6ce07976f 100644
--- a/internal/backend/sftp/sftp.go
+++ b/internal/backend/sftp/sftp.go
@@ -354,14 +354,13 @@ func (r *SFTP) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader
 			debug.Log("sftp: failed to remove broken file %v: %v",
 				f.Name(), rmErr)
 		}
-
-		err = r.checkNoSpace(dirname, rd.Length(), err)
 	}()
 
 	// save data, make sure to use the optimized sftp upload method
 	wbytes, err := f.ReadFrom(rd)
 	if err != nil {
 		_ = f.Close()
+		err = r.checkNoSpace(dirname, rd.Length(), err)
 		return errors.Wrap(err, "Write")
 	}
 
@@ -403,7 +402,7 @@ func (r *SFTP) checkNoSpace(dir string, size int64, origErr error) error {
 		debug.Log("sftp: StatVFS returned %v", err)
 		return origErr
 	}
-	if fsinfo.Favail == 0 || fsinfo.FreeSpace() < uint64(size) {
+	if fsinfo.Favail == 0 || fsinfo.Frsize*fsinfo.Bavail < uint64(size) {
 		err := errors.New("sftp: no space left on device")
 		return backoff.Permanent(err)
 	}

From 83d23b3ae816d1902a9066dcdccaf5274899bcda Mon Sep 17 00:00:00 2001
From: greatroar <61184462+greatroar@users.noreply.github.com>
Date: Wed, 7 Dec 2022 22:36:52 +0100
Subject: [PATCH 2/2] Changelog for ENOSPC handling bug

---
 changelog/unreleased/issue-3336 | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 changelog/unreleased/issue-3336

diff --git a/changelog/unreleased/issue-3336 b/changelog/unreleased/issue-3336
new file mode 100644
index 000000000..b22ab244f
--- /dev/null
+++ b/changelog/unreleased/issue-3336
@@ -0,0 +1,12 @@
+Bugfix: SFTP backend now checks for disk space
+
+A backup to an SFTP backend would spew repeated SSH_FX_FAILURE messages when
+the remote disk is full. Restic now reports "sftp: no space left on device"
+and exits immediately when it detects this condition.
+
+A fix for this issue was promised in restic 0.12.1, but the fix itself
+contained a bug that prevented it from triggering.
+
+https://github.com/restic/restic/issues/3336
+https://github.com/restic/restic/pull/3345
+https://github.com/restic/restic/pull/4075