From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [PATCH] fs: make sure to invalidate pages if we fall back on buffered reads Date: Fri, 11 Jun 2010 15:22:01 -0400 Message-ID: References: <1276007044-17715-1-git-send-email-josef@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Josef Bacik Return-path: In-Reply-To: <1276007044-17715-1-git-send-email-josef@redhat.com> (Josef Bacik's message of "Tue, 8 Jun 2010 10:24:04 -0400") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Josef Bacik writes: > Since BTRFS can fallback on buffered reads after having done some direct reads, > we need to make sure to invalidate any pages that we may have read by doing > buffered IO. This shouldn't have shown up as a visible user problem, it's just > for correctness sake. Thanks, This looks right to me. You definitely don't want to fill up the page cache from direct I/O. Reviewed-by: Jeff Moyer > Signed-off-by: Josef Bacik > --- > mm/filemap.c | 9 ++++++++- > 1 files changed, 8 insertions(+), 1 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 829ac9c..ca5aba9 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1266,6 +1266,7 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, > unsigned long seg = 0; > size_t count; > loff_t *ppos = &iocb->ki_pos; > + bool invalidate = false; > > count = 0; > retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); > @@ -1291,7 +1292,8 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, > iov, pos, nr_segs); > } > if (retval > 0) { > - *ppos = pos + retval; > + pos += retval; > + *ppos = pos; > count -= retval; > } > > @@ -1307,6 +1309,7 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, > file_accessed(filp); > goto out; > } > + invalidate = true; > } > } > > @@ -1343,6 +1346,10 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov, > if (desc.count > 0) > break; > } > + if (invalidate && retval > 0) > + invalidate_mapping_pages(filp->f_mapping, > + pos >> PAGE_CACHE_SHIFT, > + (*ppos - 1) >> PAGE_CACHE_SHIFT); > out: > return retval; > }