ceph: avoid sending unnessesary FLUSHSNAP message
when a snap notification contains no new snapshot, we can avoid sending FLUSHSNAP message to MDS. But we still need to create cap_snap in some case because it's required by write path and page writeback path Signed-off-by: Yan, Zheng <zyan@redhat.com>
This commit is contained in:
Yan, Zheng
Ilya Dryomov
Родитель
5dda377cf0
Коммит
8605609049
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@ -1297,11 +1297,8 @@ retry:
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if (capsnap->dirty_pages || capsnap->writing)
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break;
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/*
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* if cap writeback already occurred, we should have dropped
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* the capsnap in ceph_put_wrbuffer_cap_refs.
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*/
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BUG_ON(capsnap->dirty == 0);
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/* should be removed by ceph_try_drop_cap_snap() */
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BUG_ON(!capsnap->need_flush);
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/* pick mds, take s_mutex */
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if (ci->i_auth_cap == NULL) {
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@ -2347,6 +2344,27 @@ void ceph_get_cap_refs(struct ceph_inode_info *ci, int caps)
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spin_unlock(&ci->i_ceph_lock);
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}
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/*
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* drop cap_snap that is not associated with any snapshot.
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* we don't need to send FLUSHSNAP message for it.
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*/
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static int ceph_try_drop_cap_snap(struct ceph_cap_snap *capsnap)
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{
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if (!capsnap->need_flush &&
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!capsnap->writing && !capsnap->dirty_pages) {
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dout("dropping cap_snap %p follows %llu\n",
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capsnap, capsnap->follows);
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ceph_put_snap_context(capsnap->context);
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list_del(&capsnap->ci_item);
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list_del(&capsnap->flushing_item);
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ceph_put_cap_snap(capsnap);
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return 1;
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}
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return 0;
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}
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/*
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* Release cap refs.
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*
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@ -2360,7 +2378,6 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had)
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{
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struct inode *inode = &ci->vfs_inode;
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int last = 0, put = 0, flushsnaps = 0, wake = 0;
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struct ceph_cap_snap *capsnap;
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spin_lock(&ci->i_ceph_lock);
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if (had & CEPH_CAP_PIN)
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@ -2382,17 +2399,17 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had)
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if (had & CEPH_CAP_FILE_WR)
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if (--ci->i_wr_ref == 0) {
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last++;
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if (!list_empty(&ci->i_cap_snaps)) {
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capsnap = list_first_entry(&ci->i_cap_snaps,
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struct ceph_cap_snap,
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ci_item);
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if (capsnap->writing) {
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capsnap->writing = 0;
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flushsnaps =
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__ceph_finish_cap_snap(ci,
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capsnap);
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wake = 1;
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}
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if (__ceph_have_pending_cap_snap(ci)) {
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struct ceph_cap_snap *capsnap =
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list_last_entry(&ci->i_cap_snaps,
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struct ceph_cap_snap,
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ci_item);
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capsnap->writing = 0;
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if (ceph_try_drop_cap_snap(capsnap))
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put++;
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else if (__ceph_finish_cap_snap(ci, capsnap))
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flushsnaps = 1;
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wake = 1;
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}
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if (ci->i_wrbuffer_ref_head == 0 &&
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ci->i_dirty_caps == 0 &&
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@ -2416,7 +2433,7 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had)
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ceph_flush_snaps(ci);
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if (wake)
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wake_up_all(&ci->i_cap_wq);
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if (put)
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while (put-- > 0)
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iput(inode);
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}
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@ -2467,25 +2484,15 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
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capsnap->dirty_pages -= nr;
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if (capsnap->dirty_pages == 0) {
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complete_capsnap = 1;
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if (capsnap->dirty == 0)
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/* cap writeback completed before we created
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* the cap_snap; no FLUSHSNAP is needed */
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drop_capsnap = 1;
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drop_capsnap = ceph_try_drop_cap_snap(capsnap);
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}
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dout("put_wrbuffer_cap_refs on %p cap_snap %p "
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" snap %lld %d/%d -> %d/%d %s%s%s\n",
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" snap %lld %d/%d -> %d/%d %s%s\n",
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inode, capsnap, capsnap->context->seq,
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ci->i_wrbuffer_ref+nr, capsnap->dirty_pages + nr,
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ci->i_wrbuffer_ref, capsnap->dirty_pages,
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last ? " (wrbuffer last)" : "",
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complete_capsnap ? " (complete capsnap)" : "",
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drop_capsnap ? " (drop capsnap)" : "");
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if (drop_capsnap) {
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ceph_put_snap_context(capsnap->context);
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list_del(&capsnap->ci_item);
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list_del(&capsnap->flushing_item);
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ceph_put_cap_snap(capsnap);
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}
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complete_capsnap ? " (complete capsnap)" : "");
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}
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spin_unlock(&ci->i_ceph_lock);
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@ -436,6 +436,14 @@ static int dup_array(u64 **dst, __le64 *src, u32 num)
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return 0;
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}
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static bool has_new_snaps(struct ceph_snap_context *o,
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struct ceph_snap_context *n)
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{
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if (n->num_snaps == 0)
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return false;
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/* snaps are in descending order */
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return n->snaps[0] > o->seq;
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}
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/*
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* When a snapshot is applied, the size/mtime inode metadata is queued
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@ -455,7 +463,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
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{
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struct inode *inode = &ci->vfs_inode;
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struct ceph_cap_snap *capsnap;
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struct ceph_snap_context *old_snapc;
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struct ceph_snap_context *old_snapc, *new_snapc;
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int used, dirty;
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capsnap = kzalloc(sizeof(*capsnap), GFP_NOFS);
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@ -469,6 +477,7 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
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dirty = __ceph_caps_dirty(ci);
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old_snapc = ci->i_head_snapc;
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new_snapc = ci->i_snap_realm->cached_context;
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/*
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* If there is a write in progress, treat that as a dirty Fw,
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@ -486,20 +495,37 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
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dout("queue_cap_snap %p already pending\n", inode);
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goto update_snapc;
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}
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if (ci->i_snap_realm->cached_context == ceph_empty_snapc) {
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dout("queue_cap_snap %p empty snapc\n", inode);
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goto update_snapc;
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}
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if (!(dirty & (CEPH_CAP_AUTH_EXCL|CEPH_CAP_XATTR_EXCL|
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CEPH_CAP_FILE_EXCL|CEPH_CAP_FILE_WR))) {
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if (ci->i_wrbuffer_ref_head == 0 &&
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!(dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))) {
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dout("queue_cap_snap %p nothing dirty|writing\n", inode);
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goto update_snapc;
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}
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BUG_ON(!old_snapc);
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dout("queue_cap_snap %p cap_snap %p queuing under %p %s\n",
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inode, capsnap, old_snapc, ceph_cap_string(dirty));
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/*
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* There is no need to send FLUSHSNAP message to MDS if there is
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* no new snapshot. But when there is dirty pages or on-going
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* writes, we still need to create cap_snap. cap_snap is needed
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* by the write path and page writeback path.
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*
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* also see ceph_try_drop_cap_snap()
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*/
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if (has_new_snaps(old_snapc, new_snapc)) {
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if (dirty & (CEPH_CAP_ANY_EXCL|CEPH_CAP_FILE_WR))
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capsnap->need_flush = true;
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} else {
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if (!(used & CEPH_CAP_FILE_WR) &&
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ci->i_wrbuffer_ref_head == 0) {
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dout("queue_cap_snap %p "
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"no new_snap|dirty_page|writing\n", inode);
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goto update_snapc;
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}
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}
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dout("queue_cap_snap %p cap_snap %p queuing under %p %s %s\n",
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inode, capsnap, old_snapc, ceph_cap_string(dirty),
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capsnap->need_flush ? "" : "no_flush");
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ihold(inode);
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atomic_set(&capsnap->nref, 1);
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@ -549,9 +575,8 @@ void ceph_queue_cap_snap(struct ceph_inode_info *ci)
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update_snapc:
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if (ci->i_head_snapc) {
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ci->i_head_snapc = ceph_get_snap_context(
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ci->i_snap_realm->cached_context);
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dout(" new snapc is %p\n", ci->i_head_snapc);
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ci->i_head_snapc = ceph_get_snap_context(new_snapc);
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dout(" new snapc is %p\n", new_snapc);
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}
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spin_unlock(&ci->i_ceph_lock);
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@ -164,6 +164,7 @@ struct ceph_cap_snap {
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int writing; /* a sync write is still in progress */
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int dirty_pages; /* dirty pages awaiting writeback */
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bool inline_data;
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bool need_flush;
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};
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static inline void ceph_put_cap_snap(struct ceph_cap_snap *capsnap)
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@ -719,8 +720,8 @@ extern void ceph_snap_exit(void);
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static inline bool __ceph_have_pending_cap_snap(struct ceph_inode_info *ci)
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{
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return !list_empty(&ci->i_cap_snaps) &&
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list_entry(ci->i_cap_snaps.prev, struct ceph_cap_snap,
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ci_item)->writing;
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list_last_entry(&ci->i_cap_snaps, struct ceph_cap_snap,
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ci_item)->writing;
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}
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/* inode.c */
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