ceph: fix flushing caps

Current ceph_fsync() only flushes dirty caps and wait for them to be
flushed. It doesn't wait for caps that has already been flushing.
This patch makes ceph_fsync() wait for pending flushing caps too.
Besides, this patch also makes caps_are_flushed() peroperly handle
tid wrapping.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index a80a899..e9b03b5 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1097,8 +1097,7 @@ void ceph_queue_caps_release(struct inode *inode)
  * caller should hold snap_rwsem (read), s_mutex.
  */
 static int __send_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
-                     int op, int used, int want, int retain, int flushing,
-                     unsigned *pflush_tid)
+                     int op, int used, int want, int retain, int flushing)
        __releases(cap->ci->i_ceph_lock)
 {
        struct ceph_inode_info *ci = cap->ci;
@@ -1170,8 +1169,6 @@ static int __send_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
                 * first ack clean Ax.
                 */
                flush_tid = ++ci->i_cap_flush_last_tid;
-               if (pflush_tid)
-                       *pflush_tid = flush_tid;
                dout(" cap_flush_tid %d\n", (int)flush_tid);
                for (i = 0; i < CEPH_CAP_BITS; i++)
                        if (flushing & (1 << i))
@@ -1724,7 +1721,7 @@ ack:
 
                /* __send_cap drops i_ceph_lock */
                delayed += __send_cap(mdsc, cap, CEPH_CAP_OP_UPDATE, cap_used,
-                                     want, retain, flushing, NULL);
+                                     want, retain, flushing);
                goto retry; /* retake i_ceph_lock and restart our cap scan. */
        }
 
@@ -1753,12 +1750,12 @@ ack:
 /*
  * Try to flush dirty caps back to the auth mds.
  */
-static int try_flush_caps(struct inode *inode, unsigned *flush_tid)
+static int try_flush_caps(struct inode *inode, u16 flush_tid[])
 {
        struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
        struct ceph_inode_info *ci = ceph_inode(inode);
-       int flushing = 0;
        struct ceph_mds_session *session = NULL;
+       int flushing = 0;
 
 retry:
        spin_lock(&ci->i_ceph_lock);
@@ -1787,17 +1784,19 @@ retry:
 
                /* __send_cap drops i_ceph_lock */
                delayed = __send_cap(mdsc, cap, CEPH_CAP_OP_FLUSH, used, want,
-                                    cap->issued | cap->implemented, flushing,
-                                    flush_tid);
-               if (!delayed)
-                       goto out_unlocked;
+                                    cap->issued | cap->implemented, flushing);
 
                spin_lock(&ci->i_ceph_lock);
-               __cap_delay_requeue(mdsc, ci);
+               if (delayed)
+                       __cap_delay_requeue(mdsc, ci);
        }
+
+       flushing = ci->i_flushing_caps;
+       if (flushing)
+               memcpy(flush_tid, ci->i_cap_flush_tid,
+                      sizeof(ci->i_cap_flush_tid));
 out:
        spin_unlock(&ci->i_ceph_lock);
-out_unlocked:
        if (session)
                mutex_unlock(&session->s_mutex);
        return flushing;
@@ -1806,19 +1805,22 @@ out_unlocked:
 /*
  * Return true if we've flushed caps through the given flush_tid.
  */
-static int caps_are_flushed(struct inode *inode, unsigned tid)
+static int caps_are_flushed(struct inode *inode, u16 flush_tid[])
 {
        struct ceph_inode_info *ci = ceph_inode(inode);
        int i, ret = 1;
 
        spin_lock(&ci->i_ceph_lock);
-       for (i = 0; i < CEPH_CAP_BITS; i++)
-               if ((ci->i_flushing_caps & (1 << i)) &&
-                   ci->i_cap_flush_tid[i] <= tid) {
+       for (i = 0; i < CEPH_CAP_BITS; i++) {
+               if (!(ci->i_flushing_caps & (1 << i)))
+                       continue;
+               // tid only has 16 bits. we need to handle wrapping
+               if ((s16)(ci->i_cap_flush_tid[i] - flush_tid[i]) <= 0) {
                        /* still flushing this bit */
                        ret = 0;
                        break;
                }
+       }
        spin_unlock(&ci->i_ceph_lock);
        return ret;
 }
@@ -1871,7 +1873,7 @@ int ceph_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
        struct inode *inode = file->f_mapping->host;
        struct ceph_inode_info *ci = ceph_inode(inode);
-       unsigned flush_tid;
+       u16 flush_tid[CEPH_CAP_BITS];
        int ret;
        int dirty;
 
@@ -1883,7 +1885,7 @@ int ceph_fsync(struct file *file, loff_t start, loff_t end, int datasync)
                return ret;
        mutex_lock(&inode->i_mutex);
 
-       dirty = try_flush_caps(inode, &flush_tid);
+       dirty = try_flush_caps(inode, flush_tid);
        dout("fsync dirty caps are %s\n", ceph_cap_string(dirty));
 
        /*
@@ -1892,7 +1894,6 @@ int ceph_fsync(struct file *file, loff_t start, loff_t end, int datasync)
         * wait for that)
         */
        if (!datasync && (dirty & ~CEPH_CAP_ANY_FILE_WR)) {
-               dout("fsync waiting for flush_tid %u\n", flush_tid);
                ret = wait_event_interruptible(ci->i_cap_wq,
                                       caps_are_flushed(inode, flush_tid));
        }
@@ -1911,14 +1912,14 @@ int ceph_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 int ceph_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
        struct ceph_inode_info *ci = ceph_inode(inode);
-       unsigned flush_tid;
+       u16 flush_tid[CEPH_CAP_BITS];
        int err = 0;
        int dirty;
        int wait = wbc->sync_mode == WB_SYNC_ALL;
 
        dout("write_inode %p wait=%d\n", inode, wait);
        if (wait) {
-               dirty = try_flush_caps(inode, &flush_tid);
+               dirty = try_flush_caps(inode, flush_tid);
                if (dirty)
                        err = wait_event_interruptible(ci->i_cap_wq,
                                       caps_are_flushed(inode, flush_tid));
@@ -1988,7 +1989,7 @@ void ceph_kick_flushing_caps(struct ceph_mds_client *mdsc,
                                             __ceph_caps_used(ci),
                                             __ceph_caps_wanted(ci),
                                             cap->issued | cap->implemented,
-                                            ci->i_flushing_caps, NULL);
+                                            ci->i_flushing_caps);
                        if (delayed) {
                                spin_lock(&ci->i_ceph_lock);
                                __cap_delay_requeue(mdsc, ci);
@@ -2027,7 +2028,7 @@ static void kick_flushing_inode_caps(struct ceph_mds_client *mdsc,
                                     __ceph_caps_used(ci),
                                     __ceph_caps_wanted(ci),
                                     cap->issued | cap->implemented,
-                                    ci->i_flushing_caps, NULL);
+                                    ci->i_flushing_caps);
                if (delayed) {
                        spin_lock(&ci->i_ceph_lock);
                        __cap_delay_requeue(mdsc, ci);