Konrad Rzeszutek Wilk
2011-May-05 18:55 UTC
[Xen-devel] [PATCH] xen-blkfront patches for 2.6.40.
I am proposing these three patches for 2.6.40.
[PATCH 1/3] xen-blkfront: fix data size for xenbus_gather in blkfront_connect
fixes a bug, while these two:
[PATCH 2/3] xen-blkfront: Provide for ''feature-flush-cache''
the BLKIF_OP_WRITE_FLUSH_CACHE operation.
[PATCH 3/3] xen-blkfront: Introduce BLKIF_OP_FLUSH_DISKCACHE support.
Provide the functionality to use the BLKIF_OP_WRITE_FLUSH_CACHE operation, which
is
negotiated with the backend if the ''feature-flush-cache'' is
advertised. Currently there
are three OSes that advertise this flag: NetBSD 5.1 (and unstable), Linux
(devel/xen-blkback-v3.1), and Solaris.
I''ve tested it with success on NetBSD 5.1 Dom0, and with Linux
v2.6.39-rc6 with
the devel/xen-blkback-v3.1 patches.
The git tree with these patches is:
git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/blkfront
drivers/block/xen-blkfront.c | 51 +++++++++++++++++++++++++++----------
include/xen/interface/io/blkif.h | 13 +++++++++
2 files changed, 50 insertions(+), 14 deletions(-)
Konrad Rzeszutek Wilk (2):
xen-blkfront: Provide for ''feature-flush-cache'' the
BLKIF_OP_WRITE_FLUSH_CACHE operation.
xen-blkfront: Introduce BLKIF_OP_FLUSH_DISKCACHE support.
Marek Marczykowski (1):
xen-blkfront: fix data size for xenbus_gather in blkfront_connect
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Konrad Rzeszutek Wilk
2011-May-05 18:55 UTC
[Xen-devel] [PATCH 1/3] xen-blkfront: fix data size for xenbus_gather in blkfront_connect
From: Marek Marczykowski <marmarek@mimuw.edu.pl> barrier variable is int, not long. This overflow caused another variable override: "err" (in PV code) and "binfo" (in xenlinux code - drivers/xen/blkfront/blkfront.c). The later caused incorrect device flags (RO/removable etc). Signed-off-by: Marek Marczykowski <marmarek@mimuw.edu.pl> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> [v1: Changed title] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- drivers/block/xen-blkfront.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 9cb8668..2075981 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1141,7 +1141,7 @@ static void blkfront_connect(struct blkfront_info *info) } err = xenbus_gather(XBT_NIL, info->xbdev->otherend, - "feature-barrier", "%lu", &barrier, + "feature-barrier", "%d", &barrier, NULL); /* -- 1.7.4.1 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-May-05 18:55 UTC
[Xen-devel] [PATCH 2/3] xen-blkfront: Provide for ''feature-flush-cache'' the BLKIF_OP_WRITE_FLUSH_CACHE operation.
The operation BLKIF_OP_WRITE_FLUSH_CACHE has existed in the Xen tree header file for years but it was never present in the Linux tree because the frontend (nor the backend) supported this interface. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- include/xen/interface/io/blkif.h | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h index 61e523a..3d5d6db 100644 --- a/include/xen/interface/io/blkif.h +++ b/include/xen/interface/io/blkif.h @@ -45,6 +45,19 @@ typedef uint64_t blkif_sector_t; #define BLKIF_OP_WRITE_BARRIER 2 /* + * Recognised if "feature-flush-cache" is present in backend xenbus + * info. A flush will ask the underlying storage hardware to flush its + * non-volatile caches as appropriate. The "feature-flush-cache" node + * contains a boolean indicating whether flush requests are likely to + * succeed or fail. Either way, a flush request may fail at any time + * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying + * block-device hardware. The boolean simply indicates whether or not it + * is worthwhile for the frontend to attempt flushes. If a backend does + * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the + * "feature-flush-cache" node! + */ +#define BLKIF_OP_FLUSH_DISKCACHE 3 +/* * Maximum scatter/gather segments per request. * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE. * NB. This could be 12 if the ring indexes weren''t stored in the same page. -- 1.7.4.1 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-May-05 18:55 UTC
[Xen-devel] [PATCH 3/3] xen-blkfront: Introduce BLKIF_OP_FLUSH_DISKCACHE support.
If the backend supports the ''feature-flush-cache'' mode, use
that
instead of the ''feature-barrier'' support.
Currently there are three backends that support the
''feature-flush-cache''
mode: NetBSD, Solaris and Linux kernel. The ''flush'' option is
much
light-weight version than the ''barrier'' support so lets try to
use as
there are no filesystems in the kernel that use full barriers anymore.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
drivers/block/xen-blkfront.c | 49 ++++++++++++++++++++++++++++++-----------
1 files changed, 36 insertions(+), 13 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 2075981..b536a9c 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -97,6 +97,7 @@ struct blkfront_info
struct blk_shadow shadow[BLK_RING_SIZE];
unsigned long shadow_free;
unsigned int feature_flush;
+ unsigned int flush_op;
int is_ready;
};
@@ -250,8 +251,7 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t
mode,
/*
* Generate a Xen blkfront IO request from a blk layer request. Reads
- * and writes are handled as expected. Since we lack a loose flush
- * request, we map flushes into a full ordered barrier.
+ * and writes are handled as expected.
*
* @req: a request struct
*/
@@ -293,14 +293,13 @@ static int blkif_queue_request(struct request *req)
if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
/*
- * Ideally we could just do an unordered
- * flush-to-disk, but all we have is a full write
- * barrier at the moment. However, a barrier write is
+ * Ideally we can do an unordered flush-to-disk. In case the
+ * backend onlysupports barriers, use that. A barrier request
* a superset of FUA, so we can implement it the same
* way. (It''s also a FLUSH+FUA, since it is
* guaranteed ordered WRT previous writes.)
*/
- ring_req->operation = BLKIF_OP_WRITE_BARRIER;
+ ring_req->operation = info->flush_op;
}
ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
@@ -433,8 +432,11 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16
sector_size)
static void xlvbd_flush(struct blkfront_info *info)
{
blk_queue_flush(info->rq, info->feature_flush);
- printk(KERN_INFO "blkfront: %s: barriers %s\n",
+ printk(KERN_INFO "blkfront: %s: %s: %s\n",
info->gd->disk_name,
+ info->flush_op == BLKIF_OP_WRITE_BARRIER ?
+ "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
+ "flush diskcache" : "barrier or flush"),
info->feature_flush ? "enabled" : "disabled");
}
@@ -720,15 +722,20 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
switch (bret->operation) {
+ case BLKIF_OP_FLUSH_DISKCACHE:
case BLKIF_OP_WRITE_BARRIER:
if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
- printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
+ printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
+ info->flush_op == BLKIF_OP_WRITE_BARRIER ?
+ "barrier" : "flush disk cache",
info->gd->disk_name);
error = -EOPNOTSUPP;
}
if (unlikely(bret->status == BLKIF_RSP_ERROR &&
info->shadow[id].req.nr_segments == 0)) {
- printk(KERN_WARNING "blkfront: %s: empty write barrier op
failed\n",
+ printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
+ info->flush_op == BLKIF_OP_WRITE_BARRIER ?
+ "barrier" : "flush disk cache",
info->gd->disk_name);
error = -EOPNOTSUPP;
}
@@ -736,6 +743,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
if (error == -EOPNOTSUPP)
error = 0;
info->feature_flush = 0;
+ info->flush_op = 0;
xlvbd_flush(info);
}
/* fall through */
@@ -1100,7 +1108,7 @@ static void blkfront_connect(struct blkfront_info *info)
unsigned long sector_size;
unsigned int binfo;
int err;
- int barrier;
+ int barrier, flush;
switch (info->connected) {
case BLKIF_STATE_CONNECTED:
@@ -1140,6 +1148,9 @@ static void blkfront_connect(struct blkfront_info *info)
return;
}
+ info->feature_flush = 0;
+ info->flush_op = 0;
+
err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
"feature-barrier", "%d", &barrier,
NULL);
@@ -1151,11 +1162,23 @@ static void blkfront_connect(struct blkfront_info *info)
*
* If there are barriers, then we use flush.
*/
- info->feature_flush = 0;
-
- if (!err && barrier)
+ if (!err && barrier) {
info->feature_flush = REQ_FLUSH | REQ_FUA;
+ info->flush_op = BLKIF_OP_WRITE_BARRIER;
+ }
+ /*
+ * And if there is "feature-flush-cache" use that above
+ * barriers.
+ */
+ err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+ "feature-flush-cache", "%d", &flush,
+ NULL);
+ if (!err && flush) {
+ info->feature_flush = REQ_FLUSH;
+ info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
+ }
+
err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
if (err) {
xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
--
1.7.4.1
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