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Enforce request limits on zvols #6294

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Enforce request limits on zvols #6294

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6 changes: 6 additions & 0 deletions include/linux/blkdev_compat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -139,6 +139,12 @@ blk_queue_set_read_ahead(struct request_queue *q, unsigned long ra_pages)
#endif
}

static inline unsigned long
blk_queue_nr_requests(struct request_queue *q)
{
return (q->nr_requests);
}

#ifndef HAVE_GET_DISK_RO
static inline int
get_disk_ro(struct gendisk *disk)
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40 changes: 40 additions & 0 deletions module/zfs/zvol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,10 @@ struct zvol_state {
kmutex_t zv_state_lock; /* protects zvol_state_t */
atomic_t zv_suspend_ref; /* refcount for suspend */
krwlock_t zv_suspend_lock; /* suspend lock */
kcondvar_t zv_write_cv; /* write queue wait */
unsigned long zv_writes; /* in-flight writes */
kcondvar_t zv_read_cv; /* read queue wait */
unsigned long zv_reads; /* in-flight reads */
};

typedef enum {
Expand Down Expand Up @@ -786,6 +790,11 @@ zvol_write(void *arg)
generic_end_io_acct(WRITE, &zv->zv_disk->part0, start_jif);
BIO_END_IO(bio, -error);
kmem_free(zvr, sizeof (zv_request_t));

mutex_enter(&zv->zv_state_lock);
zv->zv_writes--;
cv_signal(&zv->zv_write_cv);
mutex_exit(&zv->zv_state_lock);
}

/*
Expand Down Expand Up @@ -873,6 +882,11 @@ zvol_discard(void *arg)
generic_end_io_acct(WRITE, &zv->zv_disk->part0, start_jif);
BIO_END_IO(bio, -error);
kmem_free(zvr, sizeof (zv_request_t));

mutex_enter(&zv->zv_state_lock);
zv->zv_writes--;
cv_signal(&zv->zv_write_cv);
mutex_exit(&zv->zv_state_lock);
}

static void
Expand Down Expand Up @@ -914,6 +928,11 @@ zvol_read(void *arg)
generic_end_io_acct(READ, &zv->zv_disk->part0, start_jif);
BIO_END_IO(bio, -error);
kmem_free(zvr, sizeof (zv_request_t));

mutex_enter(&zv->zv_state_lock);
zv->zv_reads--;
cv_signal(&zv->zv_read_cv);
mutex_exit(&zv->zv_state_lock);
}

static MAKE_REQUEST_FN_RET
Expand Down Expand Up @@ -962,6 +981,12 @@ zvol_request(struct request_queue *q, struct bio *bio)
goto out;
}

mutex_enter(&zv->zv_state_lock);
while (zv->zv_writes >= blk_queue_nr_requests(zv->zv_queue))
cv_wait(&zv->zv_write_cv, &zv->zv_state_lock);
zv->zv_writes++;
mutex_exit(&zv->zv_state_lock);

zvr = kmem_alloc(sizeof (zv_request_t), KM_SLEEP);
zvr->zv = zv;
zvr->bio = bio;
Expand Down Expand Up @@ -994,6 +1019,12 @@ zvol_request(struct request_queue *q, struct bio *bio)
zvol_write(zvr);
}
} else {
mutex_enter(&zv->zv_state_lock);
while (zv->zv_reads >= blk_queue_nr_requests(zv->zv_queue))
cv_wait(&zv->zv_read_cv, &zv->zv_state_lock);
zv->zv_reads++;
mutex_exit(&zv->zv_state_lock);

zvr = kmem_alloc(sizeof (zv_request_t), KM_SLEEP);
zvr->zv = zv;
zvr->bio = bio;
Expand Down Expand Up @@ -1655,6 +1686,10 @@ zvol_alloc(dev_t dev, const char *name)
list_link_init(&zv->zv_next);

mutex_init(&zv->zv_state_lock, NULL, MUTEX_DEFAULT, NULL);
cv_init(&zv->zv_write_cv, NULL, CV_DEFAULT, NULL);
cv_init(&zv->zv_read_cv, NULL, CV_DEFAULT, NULL);
zv->zv_reads = 0;
zv->zv_writes = 0;

zv->zv_queue = blk_alloc_queue(GFP_ATOMIC);
if (zv->zv_queue == NULL)
Expand Down Expand Up @@ -1741,7 +1776,12 @@ zvol_free(void *arg)

ida_simple_remove(&zvol_ida, MINOR(zv->zv_dev) >> ZVOL_MINOR_BITS);

ASSERT0(zv->zv_reads);
ASSERT0(zv->zv_writes);

mutex_destroy(&zv->zv_state_lock);
cv_destroy(&zv->zv_write_cv);
cv_destroy(&zv->zv_read_cv);

kmem_free(zv, sizeof (zvol_state_t));
}
Expand Down