On Thu, Feb 28, 2013 at 10:46 PM, Yan, Zheng <[email protected]> wrote:
> From: "Yan, Zheng" <[email protected]>
>
> ceph_aio_write() has an optimization that marks CEPH_CAP_FILE_WR
> cap dirty before data is copied to page cache and inode size is
> updated. The optimization avoids slow cap revocation caused by
> balance_dirty_pages(), but introduces inode size update race. If
> ceph_check_caps() flushes the dirty cap before the inode size is
> updated, MDS can miss the new inode size. So just remove the
> optimization.
>
> Signed-off-by: Yan, Zheng <[email protected]>
> ---
> fs/ceph/file.c | 42 +++++++++++++++++-------------------------
> 1 file changed, 17 insertions(+), 25 deletions(-)
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index a949805..28ef273 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -724,9 +724,12 @@ static ssize_t ceph_aio_write(struct kiocb *iocb, const
> struct iovec *iov,
> if (ceph_snap(inode) != CEPH_NOSNAP)
> return -EROFS;
>
> + sb_start_write(inode->i_sb);
> retry_snap:
> - if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
> - return -ENOSPC;
> + if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL)) {
> + ret = -ENOSPC;
> + goto out;
> + }
> __ceph_do_pending_vmtruncate(inode);
> dout("aio_write %p %llx.%llx %llu~%u getting caps. i_size %llu\n",
> inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
> @@ -750,29 +753,10 @@ retry_snap:
> ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,
> &iocb->ki_pos);
> } else {
> - /*
> - * buffered write; drop Fw early to avoid slow
> - * revocation if we get stuck on balance_dirty_pages
> - */
> - int dirty;
> -
> - spin_lock(&ci->i_ceph_lock);
> - dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
> - spin_unlock(&ci->i_ceph_lock);
> - ceph_put_cap_refs(ci, got);
> -
> - ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
> - if ((ret >= 0 || ret == -EIOCBQUEUED) &&
> - ((file->f_flags & O_SYNC) ||
> IS_SYNC(file->f_mapping->host)
> - || ceph_osdmap_flag(osdc->osdmap,
> CEPH_OSDMAP_NEARFULL))) {
> - err = vfs_fsync_range(file, pos, pos + ret - 1, 1);
> - if (err < 0)
> - ret = err;
> - }
> -
> - if (dirty)
> - __mark_inode_dirty(inode, dirty);
> - goto out;
> + mutex_lock(&inode->i_mutex);
> + ret = __generic_file_aio_write(iocb, iov, nr_segs,
> + &iocb->ki_pos);
> + mutex_unlock(&inode->i_mutex);
Hmm, you're here passing in a different value than the removed
generic_file_aio_write() call did — &iocb->ki_pos instead of pos.
Everything else is using the pos parameter so I rather expect that
should still be used here?
Also a quick skim of the interfaces makes me think that the two
versions aren't interchangeable — __generic_file_aio_write() also
handles O_SYNC in addition to grabbing i_mutex. Why'd you switch them?
(I haven't checked deep enough to see if the unlocked version is
correct or not, but it does say that's what most filesystems should
use.)
-Greg
> }
>
> if (ret >= 0) {
> @@ -790,12 +774,20 @@ out_put:
> ceph_cap_string(got));
> ceph_put_cap_refs(ci, got);
>
> + if (ret >= 0 &&
> + ((file->f_flags & O_SYNC) || IS_SYNC(file->f_mapping->host) ||
> + ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL))) {
> + err = vfs_fsync_range(file, pos, pos + ret - 1, 1);
> + if (err < 0)
> + ret = err;
> + }
> out:
> if (ret == -EOLDSNAPC) {
> dout("aio_write %p %llx.%llx %llu~%u got EOLDSNAPC,
> retrying\n",
> inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len);
> goto retry_snap;
> }
> + sb_end_write(inode->i_sb);
>
> return ret;
> }
> --
> 1.7.11.7
>
> --
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