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| author | Wu Fengguang <fengguang.wu@intel.com> | 2008-12-23 15:21:30 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-01-18 10:44:03 -0800 |
| commit | e283c6453018d3cec1d696fcd3ecaa9a72b7cff8 (patch) | |
| tree | 0dc34710e3b7b7d920a97a88260dc6a5d3c75309 | |
| parent | ab37645aa3488e0bf3be4dd25dad5d69680e7b9b (diff) | |
| download | lwn-e283c6453018d3cec1d696fcd3ecaa9a72b7cff8.tar.gz lwn-e283c6453018d3cec1d696fcd3ecaa9a72b7cff8.zip | |
nfs: remove redundant tests on reading new pages
commit 136221fc3219b3805c48db5da065e8e3467175d4 upstream.
aops->readpages() and its NFS helper readpage_async_filler() will only
be called to do readahead I/O for newly allocated pages. So it's not
necessary to test for the always 0 dirty/uptodate page flags.
The removal of nfs_wb_page() call also fixes a readahead bug: the NFS
readahead has been synchronous since 2.6.23, because that call will
clear PG_readahead, which is the reminder for asynchronous readahead.
More background: the PG_readahead page flag is shared with PG_reclaim,
one for read path and the other for write path. clear_page_dirty_for_io()
unconditionally clears PG_readahead to prevent possible readahead residuals,
assuming itself to be always called in the write path. However, NFS is one
and the only exception in that it _always_ calls clear_page_dirty_for_io()
in the read path, i.e. for readpages()/readpage().
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Wu Fengguang <wfg@linux.intel.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/nfs/read.c | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/fs/nfs/read.c b/fs/nfs/read.c index 40d17987d0e8..f856004bb7fa 100644 --- a/fs/nfs/read.c +++ b/fs/nfs/read.c @@ -533,12 +533,6 @@ readpage_async_filler(void *data, struct page *page) unsigned int len; int error; - error = nfs_wb_page(inode, page); - if (error) - goto out_unlock; - if (PageUptodate(page)) - goto out_unlock; - len = nfs_page_length(page); if (len == 0) return nfs_return_empty_page(page); |