Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'block-6.11-20240912' of git://git.kernel.dk/linux
Pull block fix from Jens Axboe:
"Just a single fix for a deadlock issue that can happen if someone
attempts to change the root disk IO scheduler with a module that
requires loading from disk.
Changing the scheduler freezes the queue while that operation is
happening, hence causing a deadlock"
* tag 'block-6.11-20240912' of git://git.kernel.dk/linux:
block: Prevent deadlocks when switching elevators
+38
-7
+21
-1
block/blk-sysfs.c
+21
-1
block/blk-sysfs.c
···
23
23
struct queue_sysfs_entry {
24
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struct attribute attr;
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ssize_t (*show)(struct gendisk *disk, char *page);
26
+
int (*load_module)(struct gendisk *disk, const char *page, size_t count);
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ssize_t (*store)(struct gendisk *disk, const char *page, size_t count);
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};
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···
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.store = _prefix##_store, \
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};
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+
#define QUEUE_RW_LOAD_MODULE_ENTRY(_prefix, _name) \
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static struct queue_sysfs_entry _prefix##_entry = { \
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+
.attr = { .name = _name, .mode = 0644 }, \
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+
.show = _prefix##_show, \
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+
.load_module = _prefix##_load_module, \
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+
.store = _prefix##_store, \
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+
}
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+
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QUEUE_RW_ENTRY(queue_requests, "nr_requests");
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QUEUE_RW_ENTRY(queue_ra, "read_ahead_kb");
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QUEUE_RW_ENTRY(queue_max_sectors, "max_sectors_kb");
···
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QUEUE_RO_ENTRY(queue_max_segments, "max_segments");
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QUEUE_RO_ENTRY(queue_max_integrity_segments, "max_integrity_segments");
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QUEUE_RO_ENTRY(queue_max_segment_size, "max_segment_size");
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-
QUEUE_RW_ENTRY(elv_iosched, "scheduler");
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+
QUEUE_RW_LOAD_MODULE_ENTRY(elv_iosched, "scheduler");
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QUEUE_RO_ENTRY(queue_logical_block_size, "logical_block_size");
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QUEUE_RO_ENTRY(queue_physical_block_size, "physical_block_size");
···
678
669
679
670
if (!entry->store)
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671
return -EIO;
672
+
673
+
/*
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+
* If the attribute needs to load a module, do it before freezing the
675
+
* queue to ensure that the module file can be read when the request
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+
* queue is the one for the device storing the module file.
677
+
*/
678
+
if (entry->load_module) {
679
+
res = entry->load_module(disk, page, length);
680
+
if (res)
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+
return res;
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+
}
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blk_mq_freeze_queue(q);
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mutex_lock(&q->sysfs_lock);
+15
-6
block/elevator.c
+15
-6
block/elevator.c
···
698
698
return 0;
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e = elevator_find_get(q, elevator_name);
701
-
if (!e) {
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-
request_module("%s-iosched", elevator_name);
703
-
e = elevator_find_get(q, elevator_name);
704
-
if (!e)
705
-
return -EINVAL;
706
-
}
701
+
if (!e)
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+
return -EINVAL;
707
703
ret = elevator_switch(q, e);
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elevator_put(e);
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return ret;
706
+
}
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+
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+
int elv_iosched_load_module(struct gendisk *disk, const char *buf,
709
+
size_t count)
710
+
{
711
+
char elevator_name[ELV_NAME_MAX];
712
+
713
+
if (!elv_support_iosched(disk->queue))
714
+
return -EOPNOTSUPP;
715
+
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+
strscpy(elevator_name, buf, sizeof(elevator_name));
717
+
718
+
return request_module("%s-iosched", strstrip(elevator_name));
710
719
}
711
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ssize_t elv_iosched_store(struct gendisk *disk, const char *buf,
+2
block/elevator.h
+2
block/elevator.h
···
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* io scheduler sysfs switching
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*/
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ssize_t elv_iosched_show(struct gendisk *disk, char *page);
151
+
int elv_iosched_load_module(struct gendisk *disk, const char *page,
152
+
size_t count);
151
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ssize_t elv_iosched_store(struct gendisk *disk, const char *page, size_t count);
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extern bool elv_bio_merge_ok(struct request *, struct bio *);