Messages in this thread | | | Date | Thu, 07 Dec 2006 14:05:00 -0500 | From | Wendy Cheng <> | Subject | Re: [Cluster-devel] Re: [GFS2] Don't flush everything on fdatasync [70/70] |
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Steven Whitehouse wrote: > Hi, > > On Fri, 2006-12-01 at 11:09 -0800, Andrew Morton wrote: > >>> I was taking my cue here from ext3 which does something similar. The >>> filemap_fdatawrite() is done by the VFS before this is called with a >>> filemap_fdatawait() afterwards. This was intended to flush the metadata >>> via (eventually) ->write_inode() although I guess I should be calling >>> write_inode_now() instead? >>> >> oh I see, you're jsut trying to write the inode itself, not the pages. >> >> write_inode_now() will write the pages, which you seem to not want to do. >> Whatever. The APIs here are a bit awkward. >> > > I've added a comment to explain whats going on here, and also the > following patch. I know it could be better, but its still an improvement > on what was there before, > > > Steve,
I'm in the middle of something else and don't have upstream kernel source handy at this moment. But I read akpm's comment as "write_inode_now" would do writepage and that is *not* what you want (?) (since vfs has done that before this call is invoked). I vaguely recalled I did try write_inode_now() on GFS1 once but had to replace it with "sync_inode" on RHEL4 (for the reason that I can't remember at this moment). I suggest you keep "sync_inode" (at least for a while until we can prove other call can do better). This "sync_inode" has been well tested out (with GFS1's fsync call).
There is another issue. It is a gray area. Note that you don't grab any glock here ... so if someone *has* written something in other nodes, this sync could miss it (?). This depends on how people expects a fsync/fdatasync should behave in a cluster filesystem. GFS1 asks for a shared lock here so it will force other node to flush the data (I personally think this is a more correct behavior). Your call though.
-- Wendy
> -------------------------------------------------------------------------------------------- > > >From 34126f9f41901ca9d7d0031c2b11fc0d6c07b72d Mon Sep 17 00:00:00 2001 > From: Steven Whitehouse <swhiteho@redhat.com> > Date: Thu, 7 Dec 2006 09:13:14 -0500 > Subject: [PATCH] [GFS2] Change gfs2_fsync() to use write_inode_now() > > This is a bit better than the previous version of gfs2_fsync() > although it would be better still if we were able to call a > function which only wrote the inode & metadata. Its no big deal > though that this will potentially write the data as well since > the VFS has already done that before calling gfs2_fsync(). I've > also added a comment to explain whats going on here. > > Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> > Cc: Andrew Morton <akpm@osdl.org> > --- > fs/gfs2/ops_file.c | 11 ++++++----- > 1 files changed, 6 insertions(+), 5 deletions(-) > > diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c > index 7bd971b..b3f1e03 100644 > --- a/fs/gfs2/ops_file.c > +++ b/fs/gfs2/ops_file.c > @@ -510,6 +510,11 @@ static int gfs2_close(struct inode *inod > * is set. For stuffed inodes we must flush the log in order to > * ensure that all data is on disk. > * > + * The call to write_inode_now() is there to write back metadata and > + * the inode itself. It does also try and write the data, but thats > + * (hopefully) a no-op due to the VFS having already called filemap_fdatawrite() > + * for us. > + * > * Returns: errno > */ > > @@ -518,10 +523,6 @@ static int gfs2_fsync(struct file *file, > struct inode *inode = dentry->d_inode; > int sync_state = inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC); > int ret = 0; > - struct writeback_control wbc = { > - .sync_mode = WB_SYNC_ALL, > - .nr_to_write = 0, > - }; > > if (gfs2_is_jdata(GFS2_I(inode))) { > gfs2_log_flush(GFS2_SB(inode), GFS2_I(inode)->i_gl); > @@ -530,7 +531,7 @@ static int gfs2_fsync(struct file *file, > > if (sync_state != 0) { > if (!datasync) > - ret = sync_inode(inode, &wbc); > + ret = write_inode_now(inode, 0); > > if (gfs2_is_stuffed(GFS2_I(inode))) > gfs2_log_flush(GFS2_SB(inode), GFS2_I(inode)->i_gl); >
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