linux-ext4 - [PATCH 28/29] xfs: support nowait semantics for xc_ctx_lock in xlog_cil

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Date:   Fri, 25 Aug 2023 21:54:30 +0800
From:   Hao Xu <hao.xu@...ux.dev>
To:     io-uring@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Cc:     Dominique Martinet <asmadeus@...ewreck.org>,
        Pavel Begunkov <asml.silence@...il.com>,
        Christian Brauner <brauner@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Stefan Roesch <shr@...com>, Clay Harris <bugs@...ycon.org>,
        Dave Chinner <david@...morbit.com>,
        "Darrick J . Wong" <djwong@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-cachefs@...hat.com,
        ecryptfs@...r.kernel.org, linux-nfs@...r.kernel.org,
        linux-unionfs@...r.kernel.org, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-btrfs@...r.kernel.org, codalist@...a.cs.cmu.edu,
        linux-f2fs-devel@...ts.sourceforge.net, cluster-devel@...hat.com,
        linux-mm@...ck.org, linux-nilfs@...r.kernel.org,
        devel@...ts.orangefs.org, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-mtd@...ts.infradead.org,
        Wanpeng Li <wanpengli@...cent.com>
Subject: [PATCH 28/29] xfs: support nowait semantics for xc_ctx_lock in xlog_cil_commit()

From: Hao Xu <howeyxu@...cent.com>

Apply trylock logic for xc_ctx_lock in xlog_cil_commit() in nowait
case and error out -EAGAIN for xlog_cil_commit().

Signed-off-by: Hao Xu <howeyxu@...cent.com>
---
 fs/xfs/xfs_log_cil.c  | 12 ++++++++++--
 fs/xfs/xfs_log_priv.h |  2 +-
 fs/xfs/xfs_trans.c    |  4 +++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index b31830ee36dd..6d054359bbb5 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -1613,7 +1613,7 @@ xlog_cil_process_intents(
  * background commit, returns without it held once background commits are
  * allowed again.
  */
-void
+int
 xlog_cil_commit(
 	struct xlog		*log,
 	struct xfs_trans	*tp,
@@ -1623,6 +1623,7 @@ xlog_cil_commit(
 	struct xfs_cil		*cil = log->l_cilp;
 	struct xfs_log_item	*lip, *next;
 	uint32_t		released_space = 0;
+	bool			nowait = tp->t_flags & XFS_TRANS_NOWAIT;
 
 	/*
 	 * Do all necessary memory allocation before we lock the CIL.
@@ -1632,7 +1633,12 @@ xlog_cil_commit(
 	xlog_cil_alloc_shadow_bufs(log, tp);
 
 	/* lock out background commit */
-	down_read(&cil->xc_ctx_lock);
+	if (nowait) {
+		if (!down_read_trylock(&cil->xc_ctx_lock))
+			return -EAGAIN;
+	} else {
+		down_read(&cil->xc_ctx_lock);
+	}
 
 	if (tp->t_flags & XFS_TRANS_HAS_INTENT_DONE)
 		released_space = xlog_cil_process_intents(cil, tp);
@@ -1668,6 +1674,8 @@ xlog_cil_commit(
 
 	/* xlog_cil_push_background() releases cil->xc_ctx_lock */
 	xlog_cil_push_background(log);
+
+	return 0;
 }
 
 /*
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 41edaa0ae869..eb7a1241deab 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -580,7 +580,7 @@ int	xlog_cil_init(struct xlog *log);
 void	xlog_cil_init_post_recovery(struct xlog *log);
 void	xlog_cil_destroy(struct xlog *log);
 bool	xlog_cil_empty(struct xlog *log);
-void	xlog_cil_commit(struct xlog *log, struct xfs_trans *tp,
+int	xlog_cil_commit(struct xlog *log, struct xfs_trans *tp,
 			xfs_csn_t *commit_seq, bool regrant);
 void	xlog_cil_set_ctx_write_state(struct xfs_cil_ctx *ctx,
 			struct xlog_in_core *iclog);
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index f1f84a3dd456..e5beda636a37 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -1037,7 +1037,9 @@ __xfs_trans_commit(
 		xfs_trans_apply_sb_deltas(tp);
 	xfs_trans_apply_dquot_deltas(tp);
 
-	xlog_cil_commit(log, tp, &commit_seq, regrant);
+	error = xlog_cil_commit(log, tp, &commit_seq, regrant);
+	if (error)
+		goto out_unreserve;
 
 	xfs_trans_free(tp);
 
-- 
2.25.1