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From: Pavel Begunkov <asml.silence@gmail.com>
To: linux-block@vger.kernel.org
Cc: Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	Matthew Wilcox <willy@infradead.org>,
	Ming Lei <ming.lei@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	io-uring@vger.kernel.org, linux-kernel@vger.kernel.org,
	target-devel@vger.kernel.org, linux-scsi@vger.kernel.org,
	linux-doc@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: [PATCH v2 4/7] target/file: allocate the bvec array as part of struct target_core_file_cmd
Date: Sat,  2 Jan 2021 15:17:36 +0000	[thread overview]
Message-ID: <20d31d34eb6fb8a10ac001e5e6c3812eddd24aa3.1609461359.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1609461359.git.asml.silence@gmail.com>

From: Christoph Hellwig <hch@lst.de>

This saves one memory allocation, and ensures the bvecs aren't freed
before the AIO completion.  This will allow the lower level code to be
optimized so that it can avoid allocating another bvec array.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 drivers/target/target_core_file.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index b0cb5b95e892..cce455929778 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -241,6 +241,7 @@ struct target_core_file_cmd {
 	unsigned long	len;
 	struct se_cmd	*cmd;
 	struct kiocb	iocb;
+	struct bio_vec	bvecs[];
 };
 
 static void cmd_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
@@ -268,29 +269,22 @@ fd_execute_rw_aio(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 	struct target_core_file_cmd *aio_cmd;
 	struct iov_iter iter = {};
 	struct scatterlist *sg;
-	struct bio_vec *bvec;
 	ssize_t len = 0;
 	int ret = 0, i;
 
-	aio_cmd = kmalloc(sizeof(struct target_core_file_cmd), GFP_KERNEL);
+	aio_cmd = kmalloc(struct_size(aio_cmd, bvecs, sgl_nents), GFP_KERNEL);
 	if (!aio_cmd)
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
-	bvec = kcalloc(sgl_nents, sizeof(struct bio_vec), GFP_KERNEL);
-	if (!bvec) {
-		kfree(aio_cmd);
-		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-	}
-
 	for_each_sg(sgl, sg, sgl_nents, i) {
-		bvec[i].bv_page = sg_page(sg);
-		bvec[i].bv_len = sg->length;
-		bvec[i].bv_offset = sg->offset;
+		aio_cmd->bvecs[i].bv_page = sg_page(sg);
+		aio_cmd->bvecs[i].bv_len = sg->length;
+		aio_cmd->bvecs[i].bv_offset = sg->offset;
 
 		len += sg->length;
 	}
 
-	iov_iter_bvec(&iter, is_write, bvec, sgl_nents, len);
+	iov_iter_bvec(&iter, is_write, aio_cmd->bvecs, sgl_nents, len);
 
 	aio_cmd->cmd = cmd;
 	aio_cmd->len = len;
@@ -307,8 +301,6 @@ fd_execute_rw_aio(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 	else
 		ret = call_read_iter(file, &aio_cmd->iocb, &iter);
 
-	kfree(bvec);
-
 	if (ret != -EIOCBQUEUED)
 		cmd_rw_aio_complete(&aio_cmd->iocb, ret, 0);
 
-- 
2.24.0


  parent reply	other threads:[~2021-01-02 15:22 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-02 15:17 [PATCH v2 0/7] no-copy bvec Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 1/7] splice: don't generate zero-len segement bvecs Pavel Begunkov
2021-01-04 16:17   ` Christoph Hellwig
2021-01-04 16:54     ` Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 2/7] bvec/iter: disallow zero-length segment bvecs Pavel Begunkov
2021-01-04 16:18   ` Christoph Hellwig
2021-01-04 16:37   ` Matthew Wilcox
2021-01-04 17:23     ` Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 3/7] block/psi: remove PSI annotations from direct IO Pavel Begunkov
2021-01-04 16:45   ` Christoph Hellwig
2021-01-02 15:17 ` Pavel Begunkov [this message]
2021-01-02 15:17 ` [PATCH v2 5/7] iov_iter: optimise bvec iov_iter_advance() Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 6/7] bio: add a helper calculating nr segments to alloc Pavel Begunkov
2021-01-02 15:17 ` [PATCH v2 7/7] bio: don't copy bvec for direct IO Pavel Begunkov
2021-01-04 16:20   ` Christoph Hellwig

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