LU-17383 statahead: quit statahead with a long time wait

If the thread is not doing stat for more than a time threshold
(@sbi->ll_sa_timeout, 30 seconds by default) then it probably does
not care too much about performance, or is no longer using this
directory.
Quit the statahead thread with a long time wait in this case.

This patch also fixes defects reported by Coverity Scan for
Lustre.

Fixes: e10bf68d7c3 ("LU-14361 statahead: regularized fname statahead pattern")
Test-Parameters: testlist=parallel-scale-nfsv4
Test-Parameters: testlist=parallel-scale-nfsv4
Test-Parameters: testlist=parallel-scale-nfsv4
Test-Parameters: testlist=parallel-scale-nfsv4
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: Ia7c478268fe12eeefa6dfae1b3c94451f010d1d5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53535
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Timothy Day <timday@amazon.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/llite/statahead.c b/lustre/llite/statahead.c
index c27b315..35aae94 100644 (file)
--- a/lustre/llite/statahead.c
+++ b/lustre/llite/statahead.c
@@ -1164,8 +1164,10 @@ static int ll_statahead_by_list(struct dentry *parent)
        if (!op_data)
                RETURN(-ENOMEM);
 
-       /* matches smp_store_release() in ll_deauthorize_statahead() */
-       while (pos != MDS_DIR_END_OFF && smp_load_acquire(&sai->sai_task)) {
+       while (pos != MDS_DIR_END_OFF &&
+              /* matches smp_store_release() in ll_deauthorize_statahead() */
+              smp_load_acquire(&sai->sai_task) &&
+              lli->lli_sa_enabled) {
                struct lu_dirpage *dp;
                struct lu_dirent  *ent;
 
@@ -1191,7 +1193,7 @@ static int ll_statahead_by_list(struct dentry *parent)
                for (ent = lu_dirent_start(dp);
                     /* matches smp_store_release() in ll_deauthorize_statahead() */
                     ent != NULL && smp_load_acquire(&sai->sai_task) &&
-                    !sa_low_hit(sai);
+                    !sa_low_hit(sai) && lli->lli_sa_enabled;
                     ent = lu_dirent_next(ent)) {
                        __u64 hash;
                        int namelen;
@@ -1246,6 +1248,8 @@ static int ll_statahead_by_list(struct dentry *parent)
                                 /* matches smp_store_release() in
                                  * ll_deauthorize_statahead() */
                                 smp_load_acquire(&sai->sai_task); })) {
+                               long timeout;
+
                                spin_lock(&lli->lli_agl_lock);
                                while (sa_sent_full(sai) &&
                                       !agl_list_empty(sai)) {
@@ -1265,7 +1269,20 @@ static int ll_statahead_by_list(struct dentry *parent)
 
                                if (!sa_sent_full(sai))
                                        break;
-                               schedule();
+
+                               /*
+                                * If the thread is not doing stat in
+                                * @sbi->ll_sa_timeout (30s) then it probably
+                                * does not care too much about performance,
+                                * or is no longer using this directory.
+                                * Stop the statahead thread in this case.
+                                */
+                               timeout = schedule_timeout(
+                                       cfs_time_seconds(sbi->ll_sa_timeout));
+                               if (timeout == 0) {
+                                       lli->lli_sa_enabled = 0;
+                                       break;
+                               }
                        }
                        __set_current_state(TASK_RUNNING);
 
@@ -2020,7 +2037,9 @@ sa_pattern_fname_detect(struct inode *dir, struct dentry *dchild)
                        lli->lli_sa_fname_index = num;
 
                        if (lli->lli_sa_match_count > LSA_FN_MATCH_HIT) {
+                               spin_lock(&lli->lli_sa_lock);
                                lli->lli_sa_pattern |= LSA_PATTERN_FN_UNIQUE;
+                               spin_unlock(&lli->lli_sa_lock);
                                GOTO(out, rc = true);
                        }
 
@@ -2342,6 +2361,7 @@ int ll_ioctl_ahead(struct file *file, struct llapi_lu_ladvise2 *ladvise)
                                __ll_sax_get(ctx);
                                fd->fd_sai = __ll_sai_get(sai);
                                rc = 0;
+                       } else {
                                rc = -EINVAL;
                                CWARN("%s: pattern %X is not ADVISE: rc = %d\n",
                                      sbi->ll_fsname, lli->lli_sa_pattern, rc);
@@ -2448,7 +2468,9 @@ void ll_statahead_enter(struct inode *dir, struct dentry *dchild)
 
        lli->lli_sa_match_count++;
        if (lli->lli_sa_match_count > LSA_FN_PREDICT_HIT) {
+               spin_lock(&lli->lli_sa_lock);
                lli->lli_sa_pattern |= LSA_PATTERN_FN_PREDICT;
+               spin_unlock(&lli->lli_sa_lock);
                lli->lli_sa_enabled = 1;
                lli->lli_sa_match_count = 0;
        }