linux-kernel - [PATCH v2 01/14] block: Add blk_validate_atomic_write_op

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Date: Mon,  4 Mar 2024 13:04:15 +0000
From: John Garry <john.g.garry@...cle.com>
To: djwong@...nel.org, hch@....de, viro@...iv.linux.org.uk, brauner@...nel.org,
        jack@...e.cz, chandan.babu@...cle.com, david@...morbit.com,
        axboe@...nel.dk
Cc: martin.petersen@...cle.com, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        tytso@....edu, jbongio@...gle.com, ojaswin@...ux.ibm.com,
        ritesh.list@...il.com, linux-block@...r.kernel.org,
        John Garry <john.g.garry@...cle.com>
Subject: [PATCH v2 01/14] block: Add blk_validate_atomic_write_op_size()

FSes will not check if the BIO submitted for an atomic write adheres to the
request_queue limits, so check in the BIO submission path.

Signed-off-by: John Garry <john.g.garry@...cle.com>
---
We really should return -EINVAL to userspce, so can be have BLK_STS_INVAL
or similar?
 block/blk-core.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index de771093b526..a1b095a68498 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -718,6 +718,18 @@ void submit_bio_noacct_nocheck(struct bio *bio)
 		__submit_bio_noacct(bio);
 }
 
+static blk_status_t blk_validate_atomic_write_op_size(struct request_queue *q,
+						 struct bio *bio)
+{
+	if (bio->bi_iter.bi_size > queue_atomic_write_unit_max_bytes(q))
+		return BLK_STS_IOERR;
+
+	if (bio->bi_iter.bi_size % queue_atomic_write_unit_min_bytes(q))
+		return BLK_STS_IOERR;
+
+	return BLK_STS_OK;
+}
+
 /**
  * submit_bio_noacct - re-submit a bio to the block device layer for I/O
  * @bio:  The bio describing the location in memory and on the device.
@@ -775,6 +787,11 @@ void submit_bio_noacct(struct bio *bio)
 	switch (bio_op(bio)) {
 	case REQ_OP_READ:
 	case REQ_OP_WRITE:
+		if (bio->bi_opf & REQ_ATOMIC) {
+			status = blk_validate_atomic_write_op_size(q, bio);
+			if (status != BLK_STS_OK)
+				goto end_io;
+		}
 		break;
 	case REQ_OP_FLUSH:
 		/*
-- 
2.31.1