From: Anand Jain <anand.j...@oracle.com>
This fix will ensure all SB copies on the disk is zeroed
when the disk is intentionally removed. This helps to
better manage disks in the user land.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
btrfs: don't double brelse on device rm
Device removal currently causes bdev removal to try to double free a bh
in the bdev:
[ 55.714833] WARNING: at fs/buffer.c:1160 __brelse+0x36/0x40()
[ 55.714833] VFS: brelse: Trying to free free buffer
Commit 7e3d9ebb1 added a double release of the bh for a device being
removed when all the supers don't fit in the device. In that case it
releases the bh assuming that it's going to read a new one, finds that
it won't read, and goes to a label that releases the bh again.
All it needed to do was only brelse() right before overwriting the
current bh with __bread().
Signed-off-by: Zach Brown <z...@redhat.com>
---
v1->v2: merge with Zach fix, commit update
fs/btrfs/volumes.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b4660c4..7243196 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1681,12 +1681,43 @@ int btrfs_rm_device(struct btrfs_root *root, char
*device_path)
* remove it from the devices list and zero out the old super
*/
if (clear_super && disk_super) {
+ u64 bytenr;
+ int i;
+
/* make sure this device isn't detected as part of
* the FS anymore
*/
memset(&disk_super->magic, 0, sizeof(disk_super->magic));
set_buffer_dirty(bh);
sync_dirty_buffer(bh);
+
+ /* clear the mirror copies of super block on the disk
+ * being removed, 0th copy is been taken care above and
+ * the below would take of the rest
+ */
+ for (i = 1; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+ bytenr = btrfs_sb_offset(i);
+ if (bytenr + BTRFS_SUPER_INFO_SIZE >=
+ i_size_read(bdev->bd_inode))
+ break;
+
+ brelse(bh);
+ bh = __bread(bdev, bytenr / 4096,
+ BTRFS_SUPER_INFO_SIZE);
+ if (!bh)
+ continue;
+
+ disk_super = (struct btrfs_super_block *)bh->b_data;
+
+ if (btrfs_super_bytenr(disk_super) != bytenr ||
+ btrfs_super_magic(disk_super) != BTRFS_MAGIC) {
+ continue;
+ }
+ memset(&disk_super->magic, 0,
+ sizeof(disk_super->magic));
+ set_buffer_dirty(bh);
+ sync_dirty_buffer(bh);
+ }
}
ret = 0;
--
1.8.5.3
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