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[12/26] Btrfs: avoid risk of a deadlock in btrfs_handle_error

Message ID e99158ed12100847bc591bffa92c8af1a01e4efb.1352217243.git.sbehrens@giantdisaster.de (mailing list archive)
State New, archived
Headers show

Commit Message

Stefan Behrens Nov. 6, 2012, 4:38 p.m. UTC
Remove the attempt to cancel a running scrub or device replace
operation in btrfs_handle_error() because it adds the risk of
a deadlock. The only penalty of not canceling the operation is
that some I/O remains active until the procedure completes.
This is basically the same thing that happens to other tasks
that are running in user mode context, they are not affected
or stopped in btrfs_handle_error(), these tasks just need to
handle write errors correctly.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
 fs/btrfs/super.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
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Patch

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 8b7cf54..bdf1f5e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -116,7 +116,16 @@  static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
 	if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 		sb->s_flags |= MS_RDONLY;
 		printk(KERN_INFO "btrfs is forced readonly\n");
-		btrfs_scrub_cancel(fs_info);
+		/*
+		 * Note that a running device replace operation is not
+		 * canceled here although there is no way to update
+		 * the progress. It would add the risk of a deadlock,
+		 * therefore the canceling is ommited. The only penalty
+		 * is that some I/O remains active until the procedure
+		 * completes. The next time when the filesystem is
+		 * mounted writeable again, the device replace
+		 * operation continues.
+		 */
 //		WARN_ON(1);
 	}
 }