[lustre-devel] [PATCH 15/27] lustre: statahead: statahead thread doesn't stop
James Simmons
jsimmons at infradead.org
Mon Apr 17 06:47:11 PDT 2023
From: Yang Sheng <ys at whamcloud.com>
Add a barrier to ensure sai_task changing can be seen
when access it without locking. Else the statahead
thread could sleep forever since wake_up was lost.
WC-bug-id: https://jira.whamcloud.com/browse/LU-15660
Lustre-commit: b977caa2dc7dddcec ("LU-15660 statahead: statahead thread doesn't stop")
Signed-off-by: Yang Sheng <ys at whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/47673
Reviewed-by: Neil Brown <neilb at suse.de>
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
Signed-off-by: James Simmons <jsimmons at infradead.org>
---
fs/lustre/llite/statahead.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/fs/lustre/llite/statahead.c b/fs/lustre/llite/statahead.c
index e6ea2ee..12d8266 100644
--- a/fs/lustre/llite/statahead.c
+++ b/fs/lustre/llite/statahead.c
@@ -1005,7 +1005,8 @@ static int ll_statahead_thread(void *arg)
goto out;
}
- while (pos != MDS_DIR_END_OFF && sai->sai_task) {
+ /* matches smp_store_release() in ll_deauthorize_statahead() */
+ while (pos != MDS_DIR_END_OFF && smp_load_acquire(&sai->sai_task)) {
struct lu_dirpage *dp;
struct lu_dirent *ent;
@@ -1029,7 +1030,9 @@ static int ll_statahead_thread(void *arg)
dp = page_address(page);
for (ent = lu_dirent_start(dp);
- ent && sai->sai_task && !sa_low_hit(sai);
+ /* matches smp_store_release() in ll_deauthorize_statahead() */
+ ent && smp_load_acquire(&sai->sai_task) &&
+ !sa_low_hit(sai);
ent = lu_dirent_next(ent)) {
struct lu_fid fid;
u64 hash;
@@ -1081,7 +1084,10 @@ static int ll_statahead_thread(void *arg)
fid_le_to_cpu(&fid, &ent->lde_fid);
while (({set_current_state(TASK_IDLE);
- sai->sai_task; })) {
+ /* matches smp_store_release() in
+ * ll_deauthorize_statahead()
+ */
+ smp_load_acquire(&sai->sai_task); })) {
spin_lock(&lli->lli_agl_lock);
while (sa_sent_full(sai) &&
!agl_list_empty(sai)) {
@@ -1163,7 +1169,8 @@ static int ll_statahead_thread(void *arg)
* for file release closedir() call to stop me.
*/
while (({set_current_state(TASK_IDLE);
- sai->sai_task; })) {
+ /* matches smp_store_release() in ll_deauthorize_statahead() */
+ smp_load_acquire(&sai->sai_task); })) {
schedule();
}
__set_current_state(TASK_RUNNING);
@@ -1244,7 +1251,8 @@ void ll_deauthorize_statahead(struct inode *dir, void *key)
*/
struct task_struct *task = sai->sai_task;
- sai->sai_task = NULL;
+ /* matches smp_load_acquire() in ll_statahead_thread() */
+ smp_store_release(&sai->sai_task, NULL);
wake_up_process(task);
}
spin_unlock(&lli->lli_sa_lock);
@@ -1634,11 +1642,10 @@ static int start_statahead_thread(struct inode *dir, struct dentry *dentry,
goto out;
}
- if (test_bit(LL_SBI_AGL_ENABLED, ll_i2sbi(parent->d_inode)->ll_flags) &&
- agl)
+ if (test_bit(LL_SBI_AGL_ENABLED, sbi->ll_flags) && agl)
ll_start_agl(parent, sai);
- atomic_inc(&ll_i2sbi(parent->d_inode)->ll_sa_total);
+ atomic_inc(&sbi->ll_sa_total);
sai->sai_task = task;
wake_up_process(task);
--
1.8.3.1
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