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block/nfs: add support for libnfs pagecache 

upcoming libnfs will have support for a read cache that can
significantly help to speed up requests since libnfs by design
circumvents the kernel cache.

Example:
 qemu -cdrom nfs://127.0.0.1/iso/my.iso?pagecache=1024

The pagecache parameters takes the maximum amount of pages to
cache.  A page in libnfs is always the NFS_BLKSIZE which is
4KB.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1463662083-20814-3-git-send-email-pl@kamp.de
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Peter Lieven 2016-05-19 14:48:03 +02:00 committed by Jeff Cody
parent 38f8d5e025
commit d99b26c42a
1 changed files with 36 additions and 1 deletions
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37
block/nfs.c
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@ -38,6 +38,7 @@
#include <nfsc/libnfs.h>
#define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
#define QEMU_NFS_MAX_PAGECACHE_SIZE (8388608 / NFS_BLKSIZE)
#define QEMU_NFS_MAX_DEBUG_LEVEL 2
typedef struct NFSClient {
@ -342,6 +343,26 @@ static int64_t nfs_client_open(NFSClient *client, const char *filename,
val = QEMU_NFS_MAX_READAHEAD_SIZE;
}
nfs_set_readahead(client->context, val);
#ifdef LIBNFS_FEATURE_PAGECACHE
nfs_set_pagecache_ttl(client->context, 0);
#endif
client->cache_used = true;
#endif
#ifdef LIBNFS_FEATURE_PAGECACHE
nfs_set_pagecache_ttl(client->context, 0);
} else if (!strcmp(qp->p[i].name, "pagecache")) {
if (open_flags & BDRV_O_NOCACHE) {
error_setg(errp, "Cannot enable NFS pagecache "
"if cache.direct = on");
goto fail;
}
if (val > QEMU_NFS_MAX_PAGECACHE_SIZE) {
error_report("NFS Warning: Truncating NFS pagecache"
" size to %d pages", QEMU_NFS_MAX_PAGECACHE_SIZE);
val = QEMU_NFS_MAX_PAGECACHE_SIZE;
}
nfs_set_pagecache(client->context, val);
nfs_set_pagecache_ttl(client->context, 0);
client->cache_used = true;
#endif
#ifdef LIBNFS_FEATURE_DEBUG
@ -524,7 +545,8 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
}
if ((state->flags & BDRV_O_NOCACHE) && client->cache_used) {
error_setg(errp, "Cannot disable cache if libnfs readahead is enabled");
error_setg(errp, "Cannot disable cache if libnfs readahead or"
" pagecache is enabled");
return -EINVAL;
}
@ -542,6 +564,15 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
return 0;
}
#ifdef LIBNFS_FEATURE_PAGECACHE
static void nfs_invalidate_cache(BlockDriverState *bs,
Error **errp)
{
NFSClient *client = bs->opaque;
nfs_pagecache_invalidate(client->context, client->fh);
}
#endif
static BlockDriver bdrv_nfs = {
.format_name = "nfs",
.protocol_name = "nfs",
@ -565,6 +596,10 @@ static BlockDriver bdrv_nfs = {
.bdrv_detach_aio_context = nfs_detach_aio_context,
.bdrv_attach_aio_context = nfs_attach_aio_context,
#ifdef LIBNFS_FEATURE_PAGECACHE
.bdrv_invalidate_cache = nfs_invalidate_cache,
#endif
};
static void nfs_block_init(void)