tree 5591383c1cbffe11512da889c971f899333f1a44
parent 271f18f102c789f59644bb6c53a69da1df72b2f4
author Jens Axboe <axboe@suse.de> 1150179970 +0200
committer Jens Axboe <axboe@nelson.home.kernel.dk> 1151075439 +0200

[PATCH] Kill PF_SYNCWRITE flag

A process flag to indicate whether we are doing sync io is incredibly
ugly. It also causes performance problems when one does a lot of async
io and then proceeds to sync it. Part of the io will go out as async,
and the other part as sync. This causes a disconnect between the
previously submitted io and the synced io. For io schedulers such as CFQ,
this will cause us lost merges and suboptimal behaviour in scheduling.

Remove PF_SYNCWRITE completely from the fsync/msync paths, and let
the O_DIRECT path just directly indicate that the writes are sync
by using WRITE_SYNC instead.

Signed-off-by: Jens Axboe <axboe@suse.de>