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authorSage Weil <sage@newdream.net>2008-08-04 10:41:27 -0400
committerChris Mason <chris.mason@oracle.com>2008-09-25 11:04:06 -0400
commit9ca9ee09c176a814189063c8b88f75c8f8e4ad19 (patch)
tree3092ed3f5dd472e66a61da9306dfa6839604c42c /fs/btrfs/transaction.h
parent3117a77370b6cb902191568e4e647cdcba083d0a (diff)
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Btrfs: fix ioctl-initiated transactions vs wait_current_trans()
Commit 597:466b27332893 (btrfs_start_transaction: wait for commits in progress) breaks the transaction start/stop ioctls by making btrfs_start_transaction conditionally wait for the next transaction to start. If an application artificially is holding a transaction open, things deadlock. This workaround maintains a count of open ioctl-initiated transactions in fs_info, and avoids wait_current_trans() if any are currently open (in start_transaction() and btrfs_throttle()). The start transaction ioctl uses a new btrfs_start_ioctl_transaction() that _does_ call wait_current_trans(), effectively pushing the join/wait decision to the outer ioctl-initiated transaction. This more or less neuters btrfs_throttle() when ioctl-initiated transactions are in use, but that seems like a pretty fundamental consequence of wrapping lots of write()'s in a transaction. Btrfs has no way to tell if the application considers a given operation as part of it's transaction. Obviously, if the transaction start/stop ioctls aren't being used, there is no effect on current behavior. Signed-off-by: Sage Weil <sage@newdream.net> --- ctree.h | 1 + ioctl.c | 12 +++++++++++- transaction.c | 18 +++++++++++++----- transaction.h | 2 ++ 4 files changed, 27 insertions(+), 6 deletions(-) Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/transaction.h')
-rw-r--r--fs/btrfs/transaction.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index f5adb23..2c73caee 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -83,6 +83,8 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
int num_blocks);
struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
int num_blocks);
+struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
+ int num_blocks);
int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
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