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author | 2015-05-01 16:57:16 +0800 | |
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committer | 2015-06-25 11:49:28 +0300 | |
commit | 860560904962d08fd38666207c910065fe53e074 (patch) | |
tree | 88a9532f9652a11bb393a4496130c532705282b9 /fs/ceph/caps.c | |
parent | ceph: set i_head_snapc when getting CEPH_CAP_FILE_WR reference (diff) | |
download | linux-860560904962d08fd38666207c910065fe53e074.tar.gz linux-860560904962d08fd38666207c910065fe53e074.tar.bz2 linux-860560904962d08fd38666207c910065fe53e074.zip |
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>
Diffstat (limited to 'fs/ceph/caps.c')
-rw-r--r-- | fs/ceph/caps.c | 69 |
1 files changed, 38 insertions, 31 deletions
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index feb8ec92f1b4..f1dbcae7c75c 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1297,11 +1297,8 @@ retry: if (capsnap->dirty_pages || capsnap->writing) break; - /* - * if cap writeback already occurred, we should have dropped - * the capsnap in ceph_put_wrbuffer_cap_refs. - */ - BUG_ON(capsnap->dirty == 0); + /* should be removed by ceph_try_drop_cap_snap() */ + BUG_ON(!capsnap->need_flush); /* pick mds, take s_mutex */ if (ci->i_auth_cap == NULL) { @@ -2347,6 +2344,27 @@ void ceph_get_cap_refs(struct ceph_inode_info *ci, int caps) spin_unlock(&ci->i_ceph_lock); } + +/* + * drop cap_snap that is not associated with any snapshot. + * we don't need to send FLUSHSNAP message for it. + */ +static int ceph_try_drop_cap_snap(struct ceph_cap_snap *capsnap) +{ + if (!capsnap->need_flush && + !capsnap->writing && !capsnap->dirty_pages) { + + dout("dropping cap_snap %p follows %llu\n", + capsnap, capsnap->follows); + ceph_put_snap_context(capsnap->context); + list_del(&capsnap->ci_item); + list_del(&capsnap->flushing_item); + ceph_put_cap_snap(capsnap); + return 1; + } + return 0; +} + /* * Release cap refs. * @@ -2360,7 +2378,6 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had) { struct inode *inode = &ci->vfs_inode; int last = 0, put = 0, flushsnaps = 0, wake = 0; - struct ceph_cap_snap *capsnap; spin_lock(&ci->i_ceph_lock); if (had & CEPH_CAP_PIN) @@ -2382,17 +2399,17 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had) if (had & CEPH_CAP_FILE_WR) if (--ci->i_wr_ref == 0) { last++; - if (!list_empty(&ci->i_cap_snaps)) { - capsnap = list_first_entry(&ci->i_cap_snaps, - struct ceph_cap_snap, - ci_item); - if (capsnap->writing) { - capsnap->writing = 0; - flushsnaps = - __ceph_finish_cap_snap(ci, - capsnap); - wake = 1; - } + if (__ceph_have_pending_cap_snap(ci)) { + struct ceph_cap_snap *capsnap = + list_last_entry(&ci->i_cap_snaps, + struct ceph_cap_snap, + ci_item); + capsnap->writing = 0; + if (ceph_try_drop_cap_snap(capsnap)) + put++; + else if (__ceph_finish_cap_snap(ci, capsnap)) + flushsnaps = 1; + wake = 1; } if (ci->i_wrbuffer_ref_head == 0 && ci->i_dirty_caps == 0 && @@ -2416,7 +2433,7 @@ void ceph_put_cap_refs(struct ceph_inode_info *ci, int had) ceph_flush_snaps(ci); if (wake) wake_up_all(&ci->i_cap_wq); - if (put) + while (put-- > 0) iput(inode); } @@ -2467,25 +2484,15 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr, capsnap->dirty_pages -= nr; if (capsnap->dirty_pages == 0) { complete_capsnap = 1; - if (capsnap->dirty == 0) - /* cap writeback completed before we created - * the cap_snap; no FLUSHSNAP is needed */ - drop_capsnap = 1; + drop_capsnap = ceph_try_drop_cap_snap(capsnap); } dout("put_wrbuffer_cap_refs on %p cap_snap %p " - " snap %lld %d/%d -> %d/%d %s%s%s\n", + " snap %lld %d/%d -> %d/%d %s%s\n", inode, capsnap, capsnap->context->seq, ci->i_wrbuffer_ref+nr, capsnap->dirty_pages + nr, ci->i_wrbuffer_ref, capsnap->dirty_pages, last ? " (wrbuffer last)" : "", - complete_capsnap ? " (complete capsnap)" : "", - drop_capsnap ? " (drop capsnap)" : ""); - if (drop_capsnap) { - ceph_put_snap_context(capsnap->context); - list_del(&capsnap->ci_item); - list_del(&capsnap->flushing_item); - ceph_put_cap_snap(capsnap); - } + complete_capsnap ? " (complete capsnap)" : ""); } spin_unlock(&ci->i_ceph_lock); |