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| author | Christoph Hellwig <hch@lst.de> | 2011-07-08 14:36:36 +0200 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2011-07-08 14:36:36 +0200 |
| commit | e163cbde981c5988c3e80ca29589132336f18a72 (patch) | |
| tree | 735c72c28476969eddd4a39d878bb194f3609888 /fs/xfs/xfs_log.c | |
| parent | 1d5ae5dfeee024d51fb2c0205035d7611a8f0c86 (diff) | |
| download | linux-e163cbde981c5988c3e80ca29589132336f18a72.tar.gz linux-e163cbde981c5988c3e80ca29589132336f18a72.tar.bz2 linux-e163cbde981c5988c3e80ca29589132336f18a72.zip | |
xfs: avoid a few disk cache flushes
There is no need for a pre-flush when doing writing the second part of a
split log buffer, and if we are using an external log there is no need
to do a full cache flush of the log device at all given that all writes
to it use the FUA flag.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Diffstat (limited to 'fs/xfs/xfs_log.c')
| -rw-r--r-- | fs/xfs/xfs_log.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 4c2d30e3b78d..0ef5eb677383 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1371,15 +1371,21 @@ xlog_sync(xlog_t *log, bp->b_flags |= XBF_SYNCIO; if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) { + bp->b_flags |= XBF_FUA; + /* - * If we have an external log device, flush the data device - * before flushing the log to make sure all meta data - * written back from the AIL actually made it to disk - * before writing out the new log tail LSN in the log buffer. + * Flush the data device before flushing the log to make + * sure all meta data written back from the AIL actually made + * it to disk before stamping the new log tail LSN into the + * log buffer. For an external log we need to issue the + * flush explicitly, and unfortunately synchronously here; + * for an internal log we can simply use the block layer + * state machine for preflushes. */ if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp) xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp); - bp->b_flags |= XBF_FUA | XBF_FLUSH; + else + bp->b_flags |= XBF_FLUSH; } ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1); @@ -1414,7 +1420,7 @@ xlog_sync(xlog_t *log, XFS_BUF_ASYNC(bp); bp->b_flags |= XBF_SYNCIO; if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) - bp->b_flags |= XBF_FUA | XBF_FLUSH; + bp->b_flags |= XBF_FUA; dptr = XFS_BUF_PTR(bp); /* * Bump the cycle numbers at the start of each block |