| commit | e283c6453018d3cec1d696fcd3ecaa9a72b7cff8 | |
| author | Wu Fengguang <fengguang.wu@intel.com> | |
| Tue, 23 Dec 2008 20:21:30 +0000 (23 15:21 -0500) | ||
| committer | Greg Kroah-Hartman <gregkh@suse.de> | |
| Sun, 18 Jan 2009 18:44:03 +0000 (18 10:44 -0800) | ||
| tree | 0dc34710e3b7b7d920a97a88260dc6a5d3c75309 | treesnapshot (tar.gz zip) |
| parent | ab37645aa3488e0bf3be4dd25dad5d69680e7b9b | commitdiff |
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>
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>
| fs/nfs/read.c | diffblobblamehistory |