The new remove_bdev() call back is mostly for multi-device filesystems
to handle device removal.
Some multi-devices filesystems like btrfs can have the ability to handle
device lose according to the setup (e.g. all chunks have extra mirrors),
thus losing a block device will not interrupt the normal operations.
Btrfs will soon implement this call back by:
- Automatically degrade the fs if read-write operations can be
maintained
- Shutdown the fs if read-write operations can not be maintained
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/super.c | 4 +++-
include/linux/fs.h | 18 ++++++++++++++++++
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/fs/super.c b/fs/super.c
index 80418ca8e215..07845d2f9ec4 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1463,7 +1463,9 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
sync_filesystem(sb);
shrink_dcache_sb(sb);
evict_inodes(sb);
- if (sb->s_op->shutdown)
+ if (sb->s_op->remove_bdev)
+ sb->s_op->remove_bdev(sb, bdev, surprise);
+ else if (sb->s_op->shutdown)
sb->s_op->shutdown(sb);
super_unlock_shared(sb);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b085f161ed22..5e84e06c7354 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2367,7 +2367,25 @@ struct super_operations {
struct shrink_control *);
long (*free_cached_objects)(struct super_block *,
struct shrink_control *);
+ /*
+ * Callback to shutdown the fs.
+ *
+ * If a fs can not afford losing any block device, implement this callback.
+ */
void (*shutdown)(struct super_block *sb);
+
+ /*
+ * Callback to handle a block device removal.
+ *
+ * Recommended to implement this for multi-device filesystems, as they
+ * may afford losing a block device and continue operations.
+ *
+ * @surprse: indicates a surprise removal. If true the device/media is
+ * already gone. Otherwise we're prepareing for an orderly
+ * removal.
+ */
+ void (*remove_bdev)(struct super_block *sb, struct block_device *bdev,
+ bool surprise);
};
/*
--
2.49.0
