From bfd084454dda2db6cc0690fafa94d4bc85a874aa Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 20 Oct 2021 09:55:33 +0200
Subject: [PATCH 1/3] loop-util: minor coding style updates

As suggested here: https://github.com/systemd/systemd/pull/21044#pullrequestreview-783530343
---
 src/shared/loop-util.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/shared/loop-util.c b/src/shared/loop-util.c
index 072acc8c47..52c47e208e 100644
--- a/src/shared/loop-util.c
+++ b/src/shared/loop-util.c
@@ -615,8 +615,7 @@ static uint32_t loop_flags_mangle(uint32_t loop_flags) {
         if (r < 0 && r != -ENXIO)
                 log_debug_errno(r, "Failed to parse $SYSTEMD_LOOP_DIRECT_IO, ignoring: %m");
 
-        SET_FLAG(loop_flags, LO_FLAGS_DIRECT_IO, r != 0); /* Turn on LO_FLAGS_DIRECT_IO by default, unless explicitly configured to off. */
-        return loop_flags;
+        return UPDATE_FLAG(loop_flags, LO_FLAGS_DIRECT_IO, r != 0); /* Turn on LO_FLAGS_DIRECT_IO by default, unless explicitly configured to off. */
 }
 
 int loop_device_make(
@@ -629,16 +628,13 @@ int loop_device_make(
 
         assert(fd >= 0);
         assert(ret);
-        assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
-
-        loop_flags = loop_flags_mangle(loop_flags);
 
         return loop_device_make_internal(
                         fd,
                         open_flags,
                         offset,
                         size,
-                        loop_flags,
+                        loop_flags_mangle(loop_flags),
                         ret);
 }
 

From aa4d3aa3ef05f64729cce1dd87ce9f7a237ede1a Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 20 Oct 2021 09:56:20 +0200
Subject: [PATCH 2/3] loop-util: add debug logging about O_RDWR vs. O_RDONLY +
 O_DIRECT mode

Once we managed to open the file let's log what we wanted and what we
got.
---
 src/shared/loop-util.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/shared/loop-util.c b/src/shared/loop-util.c
index 52c47e208e..f2f4ab481d 100644
--- a/src/shared/loop-util.c
+++ b/src/shared/loop-util.c
@@ -646,6 +646,7 @@ int loop_device_make_by_path(
 
         int r, basic_flags, direct_flags, rdwr_flags;
         _cleanup_close_ int fd = -1;
+        bool direct = false;
 
         assert(path);
         assert(ret);
@@ -666,6 +667,8 @@ int loop_device_make_by_path(
         fd = open(path, basic_flags|direct_flags|rdwr_flags);
         if (fd < 0 && direct_flags != 0) /* If we had O_DIRECT on, and things failed with that, let's immediately try again without */
                 fd = open(path, basic_flags|rdwr_flags);
+        else
+                direct = direct_flags != 0;
         if (fd < 0) {
                 r = -errno;
 
@@ -676,6 +679,8 @@ int loop_device_make_by_path(
                 fd = open(path, basic_flags|direct_flags|O_RDONLY);
                 if (fd < 0 && direct_flags != 0) /* as above */
                         fd = open(path, basic_flags|O_RDONLY);
+                else
+                        direct = direct_flags != 0;
                 if (fd < 0)
                         return r; /* Propagate original error */
 
@@ -683,6 +688,13 @@ int loop_device_make_by_path(
         } else if (open_flags < 0)
                 open_flags = O_RDWR;
 
+        log_debug("Opened '%s' in %s access mode%s, with O_DIRECT %s%s.",
+                  path,
+                  open_flags == O_RDWR ? "O_RDWR" : "O_RDONLY",
+                  open_flags != rdwr_flags ? " (O_RDWR was requested but not allowed)" : "",
+                  direct ? "enabled" : "disabled",
+                  direct != (direct_flags != 0) ? " (O_DIRECT was requested but not supported)" : "");
+
         return loop_device_make(fd, open_flags, 0, 0, loop_flags, ret);
 }
 

From 0193b93eb5d4c9bb760f0e2727b4e698c392a47f Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 20 Oct 2021 09:57:16 +0200
Subject: [PATCH 3/3] loop-util: call loop_device_make_internal() at the right
 place

The whole reason loop_device_make_internal() exists (as opposed to just
loop_device_make()) is to avoid mangling the loop flags value/call
getenv twice. Hence let's actually call it when we already mangled the
flags value.
---
 src/shared/loop-util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/shared/loop-util.c b/src/shared/loop-util.c
index f2f4ab481d..2da101b748 100644
--- a/src/shared/loop-util.c
+++ b/src/shared/loop-util.c
@@ -695,7 +695,7 @@ int loop_device_make_by_path(
                   direct ? "enabled" : "disabled",
                   direct != (direct_flags != 0) ? " (O_DIRECT was requested but not supported)" : "");
 
-        return loop_device_make(fd, open_flags, 0, 0, loop_flags, ret);
+        return loop_device_make_internal(fd, open_flags, 0, 0, loop_flags, ret);
 }
 
 LoopDevice* loop_device_unref(LoopDevice *d) {