diff options
| author | Josef Bacik <jbacik@fusionio.com> | 2012-09-14 10:34:40 -0400 |
|---|---|---|
| committer | Chris Mason <chris.mason@fusionio.com> | 2012-10-04 09:39:56 -0400 |
| commit | 60376ce4a8396bc5cd777be05b6a9bf044520f42 (patch) | |
| tree | 9648ab1c651557c640b8cdd24ce18d75b434c510 | |
| parent | b3ae244e7174d981c09ad7a6a68e7909d600aaca (diff) | |
| download | kernel-common-60376ce4a8396bc5cd777be05b6a9bf044520f42.tar.gz kernel-common-60376ce4a8396bc5cd777be05b6a9bf044520f42.tar.bz2 kernel-common-60376ce4a8396bc5cd777be05b6a9bf044520f42.zip | |
Btrfs: fix race in sync and freeze again
I screwed this up, there is a race between checking if there is a running
transaction and actually starting a transaction in sync where we could race
with a freezer and get ourselves into trouble. To fix this we need to make
a new join type to only do the try lock on the freeze stuff. If it fails
we'll return EPERM and just return from sync. This fixes a hang Liu Bo
reported when running xfstest 68 in a loop. Thanks,
Reported-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
| -rw-r--r-- | fs/btrfs/super.c | 15 | ||||
| -rw-r--r-- | fs/btrfs/transaction.c | 12 | ||||
| -rw-r--r-- | fs/btrfs/transaction.h | 1 |
3 files changed, 18 insertions, 10 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 867e8e799dea..903ab2d7068a 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -854,16 +854,13 @@ int btrfs_sync_fs(struct super_block *sb, int wait) btrfs_wait_ordered_extents(root, 0, 0); - spin_lock(&fs_info->trans_lock); - if (!fs_info->running_transaction) { - spin_unlock(&fs_info->trans_lock); - return 0; - } - spin_unlock(&fs_info->trans_lock); - - trans = btrfs_join_transaction(root); - if (IS_ERR(trans)) + trans = btrfs_join_transaction_freeze(root); + if (IS_ERR(trans)) { + /* Frozen, don't bother */ + if (PTR_ERR(trans) == -EPERM) + return 0; return PTR_ERR(trans); + } return btrfs_commit_transaction(trans, root); } diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index c01dec70c960..e4bfac8d54b8 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -272,6 +272,7 @@ enum btrfs_trans_type { TRANS_JOIN, TRANS_USERSPACE, TRANS_JOIN_NOLOCK, + TRANS_JOIN_FREEZE, }; static int may_wait_transaction(struct btrfs_root *root, int type) @@ -341,7 +342,11 @@ again: if (!h) return ERR_PTR(-ENOMEM); - sb_start_intwrite(root->fs_info->sb); + if (!__sb_start_write(root->fs_info->sb, SB_FREEZE_FS, false)) { + if (type == TRANS_JOIN_FREEZE) + return ERR_PTR(-EPERM); + sb_start_intwrite(root->fs_info->sb); + } if (may_wait_transaction(root, type)) wait_current_trans(root); @@ -424,6 +429,11 @@ struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root return start_transaction(root, 0, TRANS_USERSPACE, 0); } +struct btrfs_trans_handle *btrfs_join_transaction_freeze(struct btrfs_root *root) +{ + return start_transaction(root, 0, TRANS_JOIN_FREEZE, 0); +} + /* wait for a transaction commit to be fully complete */ static noinline void wait_for_commit(struct btrfs_root *root, struct btrfs_transaction *commit) diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index b6463e128048..fbf8313b9d67 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -102,6 +102,7 @@ struct btrfs_trans_handle *btrfs_start_transaction_noflush( struct btrfs_root *root, int num_items); struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root); struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root); +struct btrfs_trans_handle *btrfs_join_transaction_freeze(struct btrfs_root *root); struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root); int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid); int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans, |