[PATCH 4/6] md: pass a queue_limits through the rdev sysfs stores

[Jack Wang <jinpu.wang@ionos.com>]

From: Jack Wang <jinpu.wang@cloud.ionos.com>

state_store() and slot_store() can add a leg, which stacks its queue
limits, and the caller has to own that update because q->limits_lock
must be taken before the array is locked and suspended.

Give the rdev sysfs store callback a queue_limits argument.
rdev_attr_store() passes NULL, so no functional change; the user
follows.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
---
 drivers/md/md.c | 45 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index c7d1f9813f5d..8ad6fe178e96 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3033,7 +3033,13 @@ static int cmd_match(const char *cmd, const char *str)
 struct rdev_sysfs_entry {
 	struct attribute attr;
 	ssize_t (*show)(struct md_rdev *, char *);
-	ssize_t (*store)(struct md_rdev *, const char *, size_t);
+	/*
+	 * @lim: a queue limits update the caller owns, or NULL.  Stores that
+	 * can add a leg to the array must stack into it rather than take
+	 * q->limits_lock themselves, see md_start_sync().
+	 */
+	ssize_t (*store)(struct md_rdev *rdev, const char *page, size_t len,
+			 struct queue_limits *lim);
 };
 
 static ssize_t
@@ -3079,7 +3085,8 @@ state_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t
-state_store(struct md_rdev *rdev, const char *buf, size_t len)
+state_store(struct md_rdev *rdev, const char *buf, size_t len,
+	    struct queue_limits *lim)
 {
 	/* can write
 	 *  faulty  - simulates an error
@@ -3257,7 +3264,8 @@ errors_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t
-errors_store(struct md_rdev *rdev, const char *buf, size_t len)
+errors_store(struct md_rdev *rdev, const char *buf, size_t len,
+	     struct queue_limits *lim)
 {
 	unsigned int n;
 	int rv;
@@ -3283,7 +3291,8 @@ slot_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t
-slot_store(struct md_rdev *rdev, const char *buf, size_t len)
+slot_store(struct md_rdev *rdev, const char *buf, size_t len,
+	   struct queue_limits *lim)
 {
 	int slot;
 	int err;
@@ -3378,7 +3387,8 @@ offset_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t
-offset_store(struct md_rdev *rdev, const char *buf, size_t len)
+offset_store(struct md_rdev *rdev, const char *buf, size_t len,
+	     struct queue_limits *lim)
 {
 	unsigned long long offset;
 	if (kstrtoull(buf, 10, &offset) < 0)
@@ -3404,7 +3414,8 @@ static ssize_t new_offset_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t new_offset_store(struct md_rdev *rdev,
-				const char *buf, size_t len)
+				const char *buf, size_t len,
+				struct queue_limits *lim)
 {
 	unsigned long long new_offset;
 	struct mddev *mddev = rdev->mddev;
@@ -3511,7 +3522,8 @@ static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
 }
 
 static ssize_t
-rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
+rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len,
+		struct queue_limits *lim)
 {
 	struct mddev *my_mddev = rdev->mddev;
 	sector_t oldsectors = rdev->sectors;
@@ -3573,7 +3585,8 @@ static ssize_t recovery_start_show(struct md_rdev *rdev, char *page)
 	return sprintf(page, "%llu\n", recovery_start);
 }
 
-static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len)
+static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len,
+				    struct queue_limits *lim)
 {
 	unsigned long long recovery_start;
 
@@ -3612,7 +3625,9 @@ static ssize_t bb_show(struct md_rdev *rdev, char *page)
 {
 	return badblocks_show(&rdev->badblocks, page, 0);
 }
-static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)
+
+static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len,
+			struct queue_limits *lim)
 {
 	int rv = badblocks_store(&rdev->badblocks, page, len, 0);
 	/* Maybe that ack was all we needed */
@@ -3627,7 +3642,9 @@ static ssize_t ubb_show(struct md_rdev *rdev, char *page)
 {
 	return badblocks_show(&rdev->badblocks, page, 1);
 }
-static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
+
+static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len,
+			 struct queue_limits *lim)
 {
 	return badblocks_store(&rdev->badblocks, page, len, 1);
 }
@@ -3641,7 +3658,8 @@ ppl_sector_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t
-ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
+ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len,
+		 struct queue_limits *lim)
 {
 	unsigned long long sector;
 
@@ -3680,7 +3698,8 @@ ppl_size_show(struct md_rdev *rdev, char *page)
 }
 
 static ssize_t
-ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len)
+ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len,
+	       struct queue_limits *lim)
 {
 	unsigned int size;
 
@@ -3766,7 +3785,7 @@ rdev_attr_store(struct kobject *kobj, struct attribute *attr,
 		if (rdev->mddev == NULL)
 			rv = -ENODEV;
 		else
-			rv = entry->store(rdev, page, length);
+			rv = entry->store(rdev, page, length, NULL);
 		suspend ? mddev_unlock_and_resume(mddev) : mddev_unlock(mddev);
 	}
 
-- 
2.43.0