On 01/28/2014 09:22 PM, Miao Xie wrote:
On Tue, 28 Jan 2014 09:55:58 -0500, Josef Bacik wrote:
On 01/14/2014 07:31 AM, Miao Xie wrote:
There was a problem in the old code:
If we failed to log the csum, we would free all the ordered extents in the log
list
including those ordered extents that were logged successfully, it would make the
log committer not to wait for the completion of the ordered extents.
This patch doesn't insert the ordered extents that is about to be logged into
a global list, instead, we insert them into a local list. If we log the ordered
extents successfully, we splice them with the global list, or we will throw them
away, then do full sync. It can also reduce the lock contention and the traverse
time of list.
If we fail to log the csums we'll return an error and commit the transaction so
it doesn't matter that we free all the ordered extents, everything will be
waited on properly. Thanks,
No. Maybe my explanation is not clear. Please consider the following case:
Task1 (sync file1) Task2 (sync file2)
btrfs_sync_file()
btrfs_sync_file()
start_log_trans()
start_log_trans()
btrfs_get_logged_extents()
btrfs_log_changed_extents()
btrfs_get_logged_extents()
btrfs_log_changed_extents() failed
btrfs_free_logged_extents()
this function will free all logged extents
including the ones that are inserted by
task1
btrfs_end_log_trans()
btrfs_sync_log()
btrfs_wait_logged_extents()
but no extents to be
waited
sync end
btrfs_wait_ordered_extents()
but this operation just wait for file2's
extents that is in the specified range.
btrfs_commit_transaction()
the committer also doesn't wait for the
extents
of file1
Ah I see then yes that's correct. I'll pull it in, thanks,
Josef
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