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FAILED: patch "[PATCH] btrfs: don't double lock the subvol_sem for rename exchange" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Dec 23, 2019

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The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 943eb3bf25f4a7b745dd799e031be276aa104d82 Mon Sep 17 00:00:00 2001
From: Josef Bacik <[email protected]>
Date: Tue, 19 Nov 2019 13:59:20 -0500
Subject: [PATCH] btrfs: don't double lock the subvol_sem for rename exchange

If we're rename exchanging two subvols we'll try to lock this lock twice, which is bad. Just lock once if either of the ino's are subvols.

Fixes cdd1fedf8261 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC [email protected] # 4.4+
Signed-off-by Josef Bacik <[email protected]>
Reviewed-by David Sterba <[email protected]>
Signed-off-by David Sterba <[email protected]>
fs/btrfs/inode.c +4 -6
index 5766c2d19896..e3c76645cad7 100644
@@ -9554,9 +9554,8 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 	btrfs_init_log_ctx(&ctx_dest, new_inode);
 
 	/* close the race window with snapshot create/destroy ioctl */
-	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
-		down_read(&fs_info->subvol_sem);
-	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
+	if (old_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    new_ino == BTRFS_FIRST_FREE_OBJECTID)
 		down_read(&fs_info->subvol_sem);
 
 	/*

@@ -9790,9 +9789,8 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 		ret = ret ? ret : ret2;
 	}
 out_notrans:
-	if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
-		up_read(&fs_info->subvol_sem);
-	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+	if (new_ino == BTRFS_FIRST_FREE_OBJECTID ||
+	    old_ino == BTRFS_FIRST_FREE_OBJECTID)
 		up_read(&fs_info->subvol_sem);
 
 	ASSERT(list_empty(&ctx_root.list));