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Make a mutex to stop the race coming into geom_disk's done routine.

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Cut up requests into smaller bits if they are longer than the drivers
disk->d_maxsize or dev->si_iosize_max.

Properly handle the race condition when using g_clone_bio() is used
without having the single-threadedness of g_down/g_up secure locking.
This commit is contained in:
Poul-Henning Kamp 2003-02-11 18:32:31 +00:00
parent 184210ff8f
commit 15c672a31d
1 changed files with 61 additions and 25 deletions
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86
sys/geom/geom_disk.c
View File

@ -50,11 +50,12 @@
#include <sys/stdint.h>
#include <machine/md_var.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <geom/geom.h>
static struct mtx g_disk_done_mtx;
static g_access_t g_disk_access;
struct g_class g_disk_class = {
@ -64,7 +65,16 @@ struct g_class g_disk_class = {
G_CLASS_INITIALIZER
};
DECLARE_GEOM_CLASS(g_disk_class, g_disk);
static void
g_disk_init(void)
{
mtx_unlock(&Giant);
g_add_class(&g_disk_class);
mtx_init(&g_disk_done_mtx, "g_disk_done", MTX_DEF, 0);
mtx_lock(&Giant);
}
DECLARE_GEOM_CLASS_INIT(g_disk_class, g_disk, g_disk_init);
static void __inline
g_disk_lock_giant(struct disk *dp)
@ -154,32 +164,24 @@ g_disk_kerneldump(struct bio *bp, struct disk *dp)
static void
g_disk_done(struct bio *bp)
{
#ifdef maybe_not
struct disk *dp;
dp = bp->bio_disk;
bp->bio_completed = bp->bio_length - bp->bio_resid;
if (!(dp->d_flags & DISKFLAG_NOGIANT)) {
DROP_GIANT();
g_std_done(bp);
PICKUP_GIANT();
} else {
g_std_done(bp);
}
#else
/* See "notes" for why we need a mutex here */
/* XXX: will witness accept a mix of Giant/unGiant drivers here ? */
mtx_lock(&g_disk_done_mtx);
bp->bio_completed = bp->bio_length - bp->bio_resid;
g_std_done(bp);
#endif
mtx_unlock(&g_disk_done_mtx);
}
static void
g_disk_start(struct bio *bp)
{
struct bio *bp2;
struct bio *bp2, *bp3;
dev_t dev;
struct disk *dp;
struct g_ioctl *gio;
int error;
off_t off;
dp = bp->bio_to->geom->softc;
dev = dp->d_dev;
@ -193,20 +195,54 @@ g_disk_start(struct bio *bp)
/* fall-through */
case BIO_READ:
case BIO_WRITE:
if (dp->d_dev->si_iosize_max != 0)
dp->d_maxsize = dp->d_dev->si_iosize_max;
#ifdef maybe
else
/*
* XXX: Who knows how many drivers have undeclared
* limitations ?
*/
dp->d_maxsize = DFLTPHYS;
#endif
off = 0;
bp3 = NULL;
bp2 = g_clone_bio(bp);
if (bp2 == NULL) {
error = ENOMEM;
break;
}
bp2->bio_done = g_disk_done;
bp2->bio_blkno = bp2->bio_offset >> DEV_BSHIFT;
bp2->bio_pblkno = bp2->bio_offset / dp->d_sectorsize;
bp2->bio_bcount = bp2->bio_length;
bp2->bio_dev = dev;
bp2->bio_disk = dp;
g_disk_lock_giant(dp);
dp->d_strategy(bp2);
g_disk_unlock_giant(dp);
do {
bp2->bio_offset += off;
bp2->bio_length -= off;
bp2->bio_data -= off;
if (bp2->bio_length > dp->d_maxsize) {
/*
* XXX: If we have a stripesize we should really
* use it here.
*/
bp2->bio_length = dp->d_maxsize;
off += dp->d_maxsize;
/*
* To avoid a race, we need to grab the next bio
* before we schedule this one. See "notes".
*/
bp3 = g_clone_bio(bp);
if (bp3 == NULL)
bp->bio_error = ENOMEM;
}
bp2->bio_done = g_disk_done;
bp2->bio_blkno = bp2->bio_offset >> DEV_BSHIFT;
bp2->bio_pblkno = bp2->bio_offset / dp->d_sectorsize;
bp2->bio_bcount = bp2->bio_length;
bp2->bio_dev = dev;
bp2->bio_disk = dp;
g_disk_lock_giant(dp);
dp->d_strategy(bp2);
g_disk_unlock_giant(dp);
bp2 = bp3;
bp3 = NULL;
} while (bp2 != NULL);
break;
case BIO_GETATTR:
if (g_handleattr_int(bp, "GEOM::fwsectors", dp->d_fwsectors))