[PATCH] btrfs: report filesystem shutdown via fserror

["Miquel Sabaté Solà" <mssola@mssola.com>]

Commit 347b7042fb26 ("Merge patch series "fs: generic file IO error
reporting"") has introduced a common framework for reporting errors to
fsnotify in a standard way.

One of the functions being introduced is 'fserror_report_shutdown' that,
when combined with the experimental support for shutdown in btrfs, it
means that user-space can also easily detect whenever a btrfs filesystem
has been marked as shutdown.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>
---
Note that the for-next branch does not include the mentioned commit. I've
built and tested this patch on top of current Linus' tree.

 fs/btrfs/fs.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index 3de3b517810e..92fcebf5766e 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -33,6 +33,7 @@
 #include "async-thread.h"
 #include "block-rsv.h"
 #include "messages.h"
+#include <linux/fserror.h>

 struct inode;
 struct super_block;
@@ -1199,8 +1200,10 @@ static inline void btrfs_force_shutdown(struct btrfs_fs_info *fs_info)
 	 * So here we only mark the fs error without flipping it RO.
 	 */
 	WRITE_ONCE(fs_info->fs_error, -EIO);
-	if (!test_and_set_bit(BTRFS_FS_STATE_EMERGENCY_SHUTDOWN, &fs_info->fs_state))
+	if (!test_and_set_bit(BTRFS_FS_STATE_EMERGENCY_SHUTDOWN, &fs_info->fs_state)) {
 		btrfs_crit(fs_info, "emergency shutdown");
+		fserror_report_shutdown(fs_info->sb, GFP_KERNEL);
+	}
 }

 /*
--
2.53.0