Patch "btrfs: move missing device handling in a dedicate function" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    btrfs: move missing device handling in a dedicate function

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-move-missing-device-handling-in-a-dedicate-fun.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4841bb739cab1b30bf6256543959cee61018ec03
Author: Nikolay Borisov <nborisov@xxxxxxxx>
Date:   Tue Jan 11 18:00:26 2022 +0200

    btrfs: move missing device handling in a dedicate function
    
    [ Upstream commit ff37c89f94be14b0e22a532d1e6d57187bfd5bb8 ]
    
    This simplifies the code flow in read_one_chunk and makes error handling
    when handling missing devices a bit simpler by reducing it to a single
    check if something went wrong. No functional changes.
    
    Reviewed-by: Su Yue <l@xxxxxxxxxx>
    Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
    Reviewed-by: David Sterba <dsterba@xxxxxxxx>
    Signed-off-by: David Sterba <dsterba@xxxxxxxx>
    Stable-dep-of: 1742e1c90c3d ("btrfs: fix extent map use-after-free when handling missing device in read_one_chunk")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c886ec81c5d0..c773ecba7c2d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -7043,6 +7043,27 @@ static void warn_32bit_meta_chunk(struct btrfs_fs_info *fs_info,
 }
 #endif
 
+static struct btrfs_device *handle_missing_device(struct btrfs_fs_info *fs_info,
+						  u64 devid, u8 *uuid)
+{
+	struct btrfs_device *dev;
+
+	if (!btrfs_test_opt(fs_info, DEGRADED)) {
+		btrfs_report_missing_device(fs_info, devid, uuid, true);
+		return ERR_PTR(-ENOENT);
+	}
+
+	dev = add_missing_dev(fs_info->fs_devices, devid, uuid);
+	if (IS_ERR(dev)) {
+		btrfs_err(fs_info, "failed to init missing device %llu: %ld",
+			  devid, PTR_ERR(dev));
+		return dev;
+	}
+	btrfs_report_missing_device(fs_info, devid, uuid, false);
+
+	return dev;
+}
+
 static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 			  struct btrfs_chunk *chunk)
 {
@@ -7130,28 +7151,17 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 				   BTRFS_UUID_SIZE);
 		args.uuid = uuid;
 		map->stripes[i].dev = btrfs_find_device(fs_info->fs_devices, &args);
-		if (!map->stripes[i].dev &&
-		    !btrfs_test_opt(fs_info, DEGRADED)) {
-			free_extent_map(em);
-			btrfs_report_missing_device(fs_info, devid, uuid, true);
-			return -ENOENT;
-		}
 		if (!map->stripes[i].dev) {
-			map->stripes[i].dev =
-				add_missing_dev(fs_info->fs_devices, devid,
-						uuid);
+			map->stripes[i].dev = handle_missing_device(fs_info,
+								    devid, uuid);
 			if (IS_ERR(map->stripes[i].dev)) {
 				free_extent_map(em);
-				btrfs_err(fs_info,
-					"failed to init missing dev %llu: %ld",
-					devid, PTR_ERR(map->stripes[i].dev));
 				return PTR_ERR(map->stripes[i].dev);
 			}
-			btrfs_report_missing_device(fs_info, devid, uuid, false);
 		}
+
 		set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
 				&(map->stripes[i].dev->dev_state));
-
 	}
 
 	write_lock(&map_tree->lock);