Messages in this thread Patch in this message | | | Date | Thu, 15 Jan 2009 12:00:25 -0800 | From | Greg KH <> | Subject | [patch 83/94] nfs: remove redundant tests on reading new pages |
| |
2.6.28-stable review patch. If anyone has any objections, please let us know.
------------------
From: Wu Fengguang <fengguang.wu@intel.com>
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 | 6 ------ 1 file changed, 6 deletions(-)
--- a/fs/nfs/read.c +++ b/fs/nfs/read.c @@ -533,12 +533,6 @@ readpage_async_filler(void *data, struct 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);
| |