On Tue, Jun 14, 2011 at 10:05 PM, Fred Isaman <iisaman@xxxxxxxxxx> wrote: > On Tue, Jun 14, 2011 at 7:01 AM, Â<tao.peng@xxxxxxx> wrote: >> Hi, Fred, >> >>> -----Original Message----- >>> From: linux-nfs-owner@xxxxxxxxxxxxxxx [mailto:linux-nfs-owner@xxxxxxxxxxxxxxx] >>> On Behalf Of Fred Isaman >>> Sent: Monday, June 13, 2011 10:44 PM >>> To: Jim Rees >>> Cc: linux-nfs@xxxxxxxxxxxxxxx; peter honeyman >>> Subject: Re: [PATCH 04/34] pnfs: hook nfs_write_begin/end to allow layout driver >>> manipulation >>> >>> On Sun, Jun 12, 2011 at 7:43 PM, Jim Rees <rees@xxxxxxxxx> wrote: >>> > From: Peng Tao <bergwolf@xxxxxxxxx> >>> > >>> > Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxxxxxx> >>> > Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx> >>> > Reported-by: Alexandros Batsakis <batsakis@xxxxxxxxxx> >>> > Signed-off-by: Andy Adamson <andros@xxxxxxxxxx> >>> > Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx> >>> > Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx> >>> > Signed-off-by: Peng Tao <bergwolf@xxxxxxxxx> >>> > --- >>> > Âfs/nfs/file.c     Â|  26 ++++++++++- >>> > Âfs/nfs/pnfs.c     Â|  41 +++++++++++++++++ >>> > Âfs/nfs/pnfs.h     Â| Â115 >>> ++++++++++++++++++++++++++++++++++++++++++++++++ >>> > Âfs/nfs/write.c     |  12 +++-- >>> > Âinclude/linux/nfs_fs.h |  Â3 +- >>> > Â5 files changed, 189 insertions(+), 8 deletions(-) >>> > >>> > diff --git a/fs/nfs/file.c b/fs/nfs/file.c >>> > index 2f093ed..1768762 100644 >>> > --- a/fs/nfs/file.c >>> > +++ b/fs/nfs/file.c >>> > @@ -384,12 +384,15 @@ static int nfs_write_begin(struct file *file, struct >>> address_space *mapping, >>> >    Âpgoff_t index = pos >> PAGE_CACHE_SHIFT; >>> >    Âstruct page *page; >>> >    Âint once_thru = 0; >>> > +    struct pnfs_layout_segment *lseg; >>> > >>> >    Âdfprintk(PAGECACHE, "NFS: write_begin(%s/%s(%ld), %u@%lld)\n", >>> >        Âfile->f_path.dentry->d_parent->d_name.name, >>> >        Âfile->f_path.dentry->d_name.name, >>> >        Âmapping->host->i_ino, len, (long long) pos); >>> > - >>> > +    lseg = pnfs_update_layout(mapping->host, >>> > +                 nfs_file_open_context(file), >>> > +                 pos, len, IOMODE_RW, GFP_NOFS); >>> >>> >>> This looks like it is left over from before the rearrangements done to >>> where pnfs_update_layout. >>> In particular, we don't want to hold the reference on the lseg from >>> here until flush time. ÂAnd there >>> seems to be no reason to. ÂIf the client needs a layout to deal with >>> read-in here, it should instead >>> trigger the nfs_want_read_modify_write clause. >> Yes, you are right. Directly calling pnfs_update_layout here can be avoided. >> But it seems triggering nfs_want_read_modify_write will acquire a read-only layout segment via readpage code path. >> For write, client will need a read-write layout segment so it would mean two layoutget for each new segment (one in nfs_readpage and one at flush time). It may not be good for performance. >> Does current generic code have method to avoid this? >> >> Thanks, >> Tao >> > > No. ÂHowever, note that this only hits in the case where you are doing > subpage writes. block layout driver need the segment to determine if it should dirty other pages in the same fsblock based on if it is a first write to an INVALID extent. So it still hits whenever an fsblock is dirtied for the first time. Thanks, Tao > > Fred > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at Âhttp://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
