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geli: Add a chicken switch for unmapped I/O

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We have a report of a panic in GELI that appears to go away when
unmapped I/O is disabled.  Add a tunable to make such investigations
easier in the future.  No functional change intended.

PR:		262894
Reviewed by:	asomers
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D34944
This commit is contained in:
Mark Johnston 2022-04-18 17:16:10 -04:00
parent cc9e659077
commit 081b4452a7
2 changed files with 15 additions and 5 deletions
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8
lib/geom/eli/geli.8
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd October 15, 2020
.Dd April 18, 2022
.Dt GELI 8
.Os
.Sh NAME
@ -886,6 +886,12 @@ Reports how many times we were looking up a Data Key and it was not in cache.
This sysctl is not updated for providers that need fewer Data Keys than the limit
specified in
.Va kern.geom.eli.key_cache_limit .
.Va kern.geom.eli.unmapped_io
Enable support for unmapped I/O buffers, currently implemented only on 64-bit
platforms.
This is an optimization which reduces the overhead of I/O processing.
This variable is intended for debugging purposes and must be set in
.Pa /boot/loader.conf .
.El
.Sh EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.

12
sys/geom/eli/g_eli.c
View File

@ -97,15 +97,19 @@ static int sysctl_g_eli_minbufs(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_kern_geom_eli, OID_AUTO, minbufs, CTLTYPE_UINT | CTLFLAG_RW |
CTLFLAG_MPSAFE, NULL, 0, sysctl_g_eli_minbufs, "IU",
"Number of GELI bufs reserved for swap transactions");
static bool g_eli_blocking_malloc = false;
SYSCTL_BOOL(_kern_geom_eli, OID_AUTO, blocking_malloc, CTLFLAG_RWTUN,
&g_eli_blocking_malloc, 0, "Use blocking malloc calls for GELI buffers");
static bool g_eli_unmapped_io = true;
SYSCTL_BOOL(_kern_geom_eli, OID_AUTO, unmapped_io, CTLFLAG_RDTUN,
&g_eli_unmapped_io, 0, "Enable support for unmapped I/O");
static struct sx g_eli_umalock; /* Controls changes to UMA zone. */
SX_SYSINIT(g_eli_umalock, &g_eli_umalock, "GELI UMA");
static uma_zone_t g_eli_uma = NULL;
static int g_eli_alloc_sz;
static volatile int g_eli_umaoutstanding;
static volatile int g_eli_devs;
static bool g_eli_blocking_malloc = false;
SYSCTL_BOOL(_kern_geom_eli, OID_AUTO, blocking_malloc, CTLFLAG_RWTUN,
&g_eli_blocking_malloc, 0, "Use blocking malloc calls for GELI buffers");
/*
* Control the number of reserved entries in the GELI zone.
@ -1137,7 +1141,7 @@ g_eli_create(struct gctl_req *req, struct g_class *mp, struct g_provider *bpp,
*/
pp = g_new_providerf(gp, "%s%s", bpp->name, G_ELI_SUFFIX);
pp->flags |= G_PF_DIRECT_SEND | G_PF_DIRECT_RECEIVE;
if (CRYPTO_HAS_VMPAGE) {
if (g_eli_unmapped_io && CRYPTO_HAS_VMPAGE) {
/*
* On DMAP architectures we can use unmapped I/O. But don't
* use it with data integrity verification. That code hasn't