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Entries are added, moved, removed, and have their metapage logsync state updated while holding that lock. jfs_flush_journal() checks log->synclist without taking log->synclock while waiting for the lazycommit thread to catch up. In debug builds it can also traverse the list and dump entries without serialization. A lazy commit can wake a flush waiter before txUnlock() updates metapage logsync state and removes the transaction block from log->synclist, so jfs_flush_journal() can sample or traverse the list concurrently with a protected updater. Use log->synclock for the flush-side empty checks and for the debug list walk. This keeps jfs_flush_journal() serialized with the existing logsync mutators without changing commit ordering. Signed-off-by: Cen Zhang --- fs/jfs/jfs_logmgr.c | 57 +++++++++++++++++++++++++++++++++------------ 1 file changed, 38 insertions(+), 19 deletions(-) diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c index ada00d5..ea607ce 100644 --- a/fs/jfs/jfs_logmgr.c +++ b/fs/jfs/jfs_logmgr.c @@ -1495,6 +1495,18 @@ int lmLogClose(struct super_block *sb) } =20 =20 +static bool jfs_log_synclist_empty(struct jfs_log *log) +{ + unsigned long flags; + bool empty; + + LOGSYNC_LOCK(log, flags); + empty =3D list_empty(&log->synclist); + LOGSYNC_UNLOCK(log, flags); + + return empty; +} + /* * NAME: jfs_flush_journal() * @@ -1575,40 +1587,47 @@ void jfs_flush_journal(struct jfs_log *log, int wai= t) * If there was recent activity, we may need to wait * for the lazycommit thread to catch up */ - if ((!list_empty(&log->cqueue)) || !list_empty(&log->synclist)) { + if ((!list_empty(&log->cqueue)) || !jfs_log_synclist_empty(log)) { for (i =3D 0; i < 200; i++) { /* Too much? */ msleep(250); write_special_inodes(log, filemap_fdatawrite); if (list_empty(&log->cqueue) && - list_empty(&log->synclist)) + jfs_log_synclist_empty(log)) break; } } assert(list_empty(&log->cqueue)); =20 #ifdef CONFIG_JFS_DEBUG - if (!list_empty(&log->synclist)) { + { + unsigned long flags; struct logsyncblk *lp; =20 - printk(KERN_ERR "jfs_flush_journal: synclist not empty\n"); - list_for_each_entry(lp, &log->synclist, synclist) { - if (lp->xflag & COMMIT_PAGE) { - struct metapage *mp =3D (struct metapage *)lp; - print_hex_dump(KERN_ERR, "metapage: ", - DUMP_PREFIX_ADDRESS, 16, 4, - mp, sizeof(struct metapage), 0); - print_hex_dump(KERN_ERR, "page: ", - DUMP_PREFIX_ADDRESS, 16, - sizeof(long), mp->folio, - sizeof(struct page), 0); - } else - print_hex_dump(KERN_ERR, "tblock:", - DUMP_PREFIX_ADDRESS, 16, 4, - lp, sizeof(struct tblock), 0); + LOGSYNC_LOCK(log, flags); + if (!list_empty(&log->synclist)) { + pr_err("%s: synclist not empty\n", __func__); + list_for_each_entry(lp, &log->synclist, synclist) { + if (lp->xflag & COMMIT_PAGE) { + struct metapage *mp =3D (struct metapage *)lp; + + print_hex_dump(KERN_ERR, "metapage: ", + DUMP_PREFIX_ADDRESS, 16, 4, + mp, sizeof(struct metapage), 0); + print_hex_dump(KERN_ERR, "page: ", + DUMP_PREFIX_ADDRESS, 16, + sizeof(long), mp->folio, + sizeof(struct page), 0); + } else { + print_hex_dump(KERN_ERR, "tblock:", + DUMP_PREFIX_ADDRESS, 16, 4, + lp, sizeof(struct tblock), 0); + } + } } + LOGSYNC_UNLOCK(log, flags); } #else - WARN_ON(!list_empty(&log->synclist)); + WARN_ON(!jfs_log_synclist_empty(log)); #endif clear_bit(log_FLUSH, &log->flag); } --=20 2.51.0