4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jeff Mahoney jeffm@suse.com
commit 5c06147128fbbdf7a84232c5f0d808f53153defe upstream.
When we fail to start a transaction in btrfs_dev_replace_start, we leave dev_replace->replace_start set to STARTED but clear ->srcdev and ->tgtdev. Later, that can result in an Oops in btrfs_dev_replace_progress when having state set to STARTED or SUSPENDED implies that ->srcdev is valid.
Also fix error handling when the state is already STARTED or SUSPENDED while starting. That, too, will clear ->srcdev and ->tgtdev even though it doesn't own them. This should be an impossible case to hit since we should be protected by the BTRFS_FS_EXCL_OP bit being set. Let's add an ASSERT there while we're at it.
Fixes: e93c89c1aaaaa (Btrfs: add new sources for device replace code) CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Jeff Mahoney jeffm@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sudip Mukherjee sudipm.mukherjee@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/dev-replace.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -350,6 +350,7 @@ int btrfs_dev_replace_start(struct btrfs break; case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED: case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED: + ASSERT(0); ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED; goto leave; } @@ -394,6 +395,10 @@ int btrfs_dev_replace_start(struct btrfs if (IS_ERR(trans)) { ret = PTR_ERR(trans); btrfs_dev_replace_lock(dev_replace, 1); + dev_replace->replace_state = + BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED; + dev_replace->srcdev = NULL; + dev_replace->tgtdev = NULL; goto leave; }
@@ -415,8 +420,6 @@ int btrfs_dev_replace_start(struct btrfs return ret;
leave: - dev_replace->srcdev = NULL; - dev_replace->tgtdev = NULL; btrfs_dev_replace_unlock(dev_replace, 1); btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device); return ret;