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  1. 20 Apr, 2009 3 commits
    • Chris Mason's avatar
      Btrfs: fix oops on page->mapping->host during writepage · 11c8349b
      Chris Mason authored 
      The extent_io writepage call updates the writepage index in the inode
as it makes progress.  But, it was doing the update after unlocking the page,
which isn't legal because page->mapping can't be trusted once the page
is unlocked.

This lead to an oops, especially common with compression turned on.  The
fix here is to update the writeback index before unlocking the page.
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      11c8349b
    • Chris Mason's avatar
      Btrfs: add a priority queue to the async thread helpers · d313d7a3
      Chris Mason authored 
      Btrfs is using WRITE_SYNC_PLUG to send down synchronous IOs with a
higher priority.  But, the checksumming helper threads prevent it
from being fully effective.

There are two problems.  First, a big queue of pending checksumming
will delay the synchronous IO behind other lower priority writes.  Second,
the checksumming uses an ordered async work queue.  The ordering makes sure
that IOs are sent to the block layer in the same order they are sent
to the checksumming threads.  Usually this gives us less seeky IO.

But, when we start mixing IO priorities, the lower priority IO can delay
the higher priority IO.

This patch solves both problems by adding a high priority list to the async
helper threads, and a new btrfs_set_work_high_prio(), which is used
to make put a new async work item onto the higher priority list.

The ordering is still done on high priority IO, but all of the high
priority bios are ordered separately from the low priority bios.  This
ordering is purely an IO optimization, it is not involved in data
or metadata integrity.
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      d313d7a3
    • Chris Mason's avatar
      Btrfs: use WRITE_SYNC for synchronous writes · ffbd517d
      Chris Mason authored 
      Part of reducing fsync/O_SYNC/O_DIRECT latencies is using WRITE_SYNC for
writes we plan on waiting on in the near future.  This patch
mirrors recent changes in other filesystems and the generic code to
use WRITE_SYNC when WB_SYNC_ALL is passed and to use WRITE_SYNC for
other latency critical writes.

Btrfs uses async worker threads for checksumming before the write is done,
and then again to actually submit the bios.  The bio submission code just
runs a per-device list of bios that need to be sent down the pipe.

This list is split into low priority and high priority lists so the
WRITE_SYNC IO happens first.
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      ffbd517d
  3. 14 Apr, 2009 27 commits
  5. 13 Apr, 2009 10 commits
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